CPU2017 Flag Description
ASUSTeK Computer Inc. ASUS RS520A-E11(KMPA-U16) Server System 2.00 GHz, AMD EPYC 7713
Compilers: AMD Optimizing C/C++ Compiler Suite
Base Compiler Invocation
-
- clang
![[user]](https://www.spec.org/auto/cpu2017/images/user.png)
- CC, LD
-
clang is a C compiler which encompasses preprocessing, parsing, optimization, code generation, assembly, and linking.
Depending on which high-level mode setting is passed, Clang will stop before doing a full link.
-
- flang
- FC, LD
-
flang is a Fortran compiler which encompasses parsing, optimization, code generation, assembly, and linking. Depending on
which high-level mode setting is passed, Flang will stop before doing a full link.
-
- flang
- FC, LD
-
flang is a Fortran compiler which encompasses parsing, optimization, code generation, assembly, and linking. Depending on
which high-level mode setting is passed, Flang will stop before doing a full link.
-
- clang
- CC
-
clang is a C compiler which encompasses preprocessing, parsing, optimization, code generation, assembly, and linking.
Depending on which high-level mode setting is passed, Clang will stop before doing a full link.
-
- clang++
- CXX, LD
-
clang++ C++ compiler which encompasses preprocessing, parsing, optimization, code generation, assembly, and linking.
Depending on which high-level mode setting is passed, Clang will stop before doing a full link.
-
- clang
- CC
-
clang is a C compiler which encompasses preprocessing, parsing, optimization, code generation, assembly, and linking.
Depending on which high-level mode setting is passed, Clang will stop before doing a full link.
-
- flang
- FC
-
flang is a Fortran compiler which encompasses parsing, optimization, code generation, assembly, and linking. Depending on
which high-level mode setting is passed, Flang will stop before doing a full link.
Peak Compiler Invocation
-
- clang
- CC, LD
-
clang is a C compiler which encompasses preprocessing, parsing, optimization, code generation, assembly, and linking.
Depending on which high-level mode setting is passed, Clang will stop before doing a full link.
-
- flang
- FC, LD
-
flang is a Fortran compiler which encompasses parsing, optimization, code generation, assembly, and linking. Depending on
which high-level mode setting is passed, Flang will stop before doing a full link.
-
- flang
- FC, LD
-
flang is a Fortran compiler which encompasses parsing, optimization, code generation, assembly, and linking. Depending on
which high-level mode setting is passed, Flang will stop before doing a full link.
-
- clang
- CC
-
clang is a C compiler which encompasses preprocessing, parsing, optimization, code generation, assembly, and linking.
Depending on which high-level mode setting is passed, Clang will stop before doing a full link.
-
- clang++
- CXX, LD
-
clang++ C++ compiler which encompasses preprocessing, parsing, optimization, code generation, assembly, and linking.
Depending on which high-level mode setting is passed, Clang will stop before doing a full link.
-
- clang
- CC
-
clang is a C compiler which encompasses preprocessing, parsing, optimization, code generation, assembly, and linking.
Depending on which high-level mode setting is passed, Clang will stop before doing a full link.
-
- flang
- FC
-
flang is a Fortran compiler which encompasses parsing, optimization, code generation, assembly, and linking. Depending on
which high-level mode setting is passed, Flang will stop before doing a full link.
Base Portability Flags
-
![[suite]](https://www.spec.org/auto/cpu2017/images/suite.png)
- EXTRA_PORTABILITY
-
This option is used to indicate that the host system's integers are 32-bits
wide, and longs and pointers are 64-bits wide. Not all benchmarks
recognize this macro, but the preferred practice for data model selection
applies the flags to all benchmarks; this flag description is a placeholder
for those benchmarks that do not recognize this macro.
-
- EXTRA_PORTABILITY
-
This option is used to indicate that the host system's integers are 32-bits
wide, and longs and pointers are 64-bits wide. Not all benchmarks
recognize this macro, but the preferred practice for data model selection
applies the flags to all benchmarks; this flag description is a placeholder
for those benchmarks that do not recognize this macro.
-
- EXTRA_PORTABILITY
-
This option is used to indicate that the host system's integers are 32-bits
wide, and longs and pointers are 64-bits wide. Not all benchmarks
recognize this macro, but the preferred practice for data model selection
applies the flags to all benchmarks; this flag description is a placeholder
for those benchmarks that do not recognize this macro.
-
-
-
- EXTRA_PORTABILITY
-
This option is used to indicate that the host system's integers are 32-bits
wide, and longs and pointers are 64-bits wide. Not all benchmarks
recognize this macro, but the preferred practice for data model selection
applies the flags to all benchmarks; this flag description is a placeholder
for those benchmarks that do not recognize this macro.
-
-
- EXTRA_PORTABILITY
-
This option is used to indicate that the host system's integers are 32-bits
wide, and longs and pointers are 64-bits wide. Not all benchmarks
recognize this macro, but the preferred practice for data model selection
applies the flags to all benchmarks; this flag description is a placeholder
for those benchmarks that do not recognize this macro.
-
-
-
- EXTRA_PORTABILITY
-
This option is used to indicate that the host system's integers are 32-bits
wide, and longs and pointers are 64-bits wide. Not all benchmarks
recognize this macro, but the preferred practice for data model selection
applies the flags to all benchmarks; this flag description is a placeholder
for those benchmarks that do not recognize this macro.
-
- EXTRA_PORTABILITY
-
This option is used to indicate that the host system's integers are 32-bits
wide, and longs and pointers are 64-bits wide. Not all benchmarks
recognize this macro, but the preferred practice for data model selection
applies the flags to all benchmarks; this flag description is a placeholder
for those benchmarks that do not recognize this macro.
-
- EXTRA_PORTABILITY
-
This option is used to indicate that the host system's integers are 32-bits
wide, and longs and pointers are 64-bits wide. Not all benchmarks
recognize this macro, but the preferred practice for data model selection
applies the flags to all benchmarks; this flag description is a placeholder
for those benchmarks that do not recognize this macro.
-
- EXTRA_PORTABILITY
-
This option is used to indicate that the host system's integers are 32-bits
wide, and longs and pointers are 64-bits wide. Not all benchmarks
recognize this macro, but the preferred practice for data model selection
applies the flags to all benchmarks; this flag description is a placeholder
for those benchmarks that do not recognize this macro.
-
- EXTRA_PORTABILITY
-
This option is used to indicate that the host system's integers are 32-bits
wide, and longs and pointers are 64-bits wide. Not all benchmarks
recognize this macro, but the preferred practice for data model selection
applies the flags to all benchmarks; this flag description is a placeholder
for those benchmarks that do not recognize this macro.
Peak Portability Flags
-
- EXTRA_PORTABILITY
-
This option is used to indicate that the host system's integers are 32-bits
wide, and longs and pointers are 64-bits wide. Not all benchmarks
recognize this macro, but the preferred practice for data model selection
applies the flags to all benchmarks; this flag description is a placeholder
for those benchmarks that do not recognize this macro.
-
- EXTRA_PORTABILITY
-
This option is used to indicate that the host system's integers are 32-bits
wide, and longs and pointers are 64-bits wide. Not all benchmarks
recognize this macro, but the preferred practice for data model selection
applies the flags to all benchmarks; this flag description is a placeholder
for those benchmarks that do not recognize this macro.
-
- EXTRA_PORTABILITY
-
This option is used to indicate that the host system's integers are 32-bits
wide, and longs and pointers are 64-bits wide. Not all benchmarks
recognize this macro, but the preferred practice for data model selection
applies the flags to all benchmarks; this flag description is a placeholder
for those benchmarks that do not recognize this macro.
-
-
-
- EXTRA_PORTABILITY
-
This option is used to indicate that the host system's integers are 32-bits
wide, and longs and pointers are 64-bits wide. Not all benchmarks
recognize this macro, but the preferred practice for data model selection
applies the flags to all benchmarks; this flag description is a placeholder
for those benchmarks that do not recognize this macro.
-
-
- EXTRA_PORTABILITY
-
This option is used to indicate that the host system's integers are 32-bits
wide, and longs and pointers are 64-bits wide. Not all benchmarks
recognize this macro, but the preferred practice for data model selection
applies the flags to all benchmarks; this flag description is a placeholder
for those benchmarks that do not recognize this macro.
-
-
-
- EXTRA_PORTABILITY
-
This option is used to indicate that the host system's integers are 32-bits
wide, and longs and pointers are 64-bits wide. Not all benchmarks
recognize this macro, but the preferred practice for data model selection
applies the flags to all benchmarks; this flag description is a placeholder
for those benchmarks that do not recognize this macro.
-
- EXTRA_PORTABILITY
-
This option is used to indicate that the host system's integers are 32-bits
wide, and longs and pointers are 64-bits wide. Not all benchmarks
recognize this macro, but the preferred practice for data model selection
applies the flags to all benchmarks; this flag description is a placeholder
for those benchmarks that do not recognize this macro.
-
- EXTRA_PORTABILITY
-
This option is used to indicate that the host system's integers are 32-bits
wide, and longs and pointers are 64-bits wide. Not all benchmarks
recognize this macro, but the preferred practice for data model selection
applies the flags to all benchmarks; this flag description is a placeholder
for those benchmarks that do not recognize this macro.
-
- EXTRA_PORTABILITY
-
This option is used to indicate that the host system's integers are 32-bits
wide, and longs and pointers are 64-bits wide. Not all benchmarks
recognize this macro, but the preferred practice for data model selection
applies the flags to all benchmarks; this flag description is a placeholder
for those benchmarks that do not recognize this macro.
-
- EXTRA_PORTABILITY
-
This option is used to indicate that the host system's integers are 32-bits
wide, and longs and pointers are 64-bits wide. Not all benchmarks
recognize this macro, but the preferred practice for data model selection
applies the flags to all benchmarks; this flag description is a placeholder
for those benchmarks that do not recognize this macro.
Base Optimization Flags
-
- -m64
- CC, LD
-
Generate code for a 64-bit environment. The 64-bit environment sets int to 32 bits and long and
pointer to 64 bits and generates code for AMD's x86-64 architecture. The compiler generates AMD64, INTEL64,
x86-64 64-bit ABI. The default on a 32-bit host is 32-bit ABI. The default on a 64-bit host is 64-bit ABI if the target
platform specified is 64-bit, otherwise the default is 32-bit.
-
-
-
-
-
-
-
- -O3
- COPTIMIZE
-
Like -O2, except that it enables optimizations that take longer to perform or that may generate larger code (in
an attempt to make the program run faster).
If multiple "O" options are used, with or without level numbers, the last such option is the one that is effective.
- Includes:
-
- -march=znver3
- COPTIMIZE
-
Specify that Clang should generate code for a specific processor family member and later. For example, if you specify
-march=znver1, the compiler is allowed to generate instructions that are valid on AMD Zen processors, but
which may not exist on earlier products.
-
-
- -ffast-math
- COPTIMIZE
-
Enables a range of optimizations that provide faster, though sometimes less precise, mathematical operations that may
not conform to the IEEE-754 specifications. When this option is specified, the __STDC_IEC_559__ macro is
ignored even if set by the system headers.
-
-
- -fstruct-layout=5
- COPTIMIZE
-
Analyzes the whole program to determine if the structures in the code can be peeled and if pointer or integer fields in
the structure can be compressed. If feasible, this optimization transforms the code to enable these improvements. This
transformation is likely to improve cache utilization and memory bandwidth. This, in turn, is expected to improve the
scalability of programs executed on multiple cores.
This is effective only under -flto as whole program analysis is required to perform this optimization. You can choose
different levels of aggressiveness with which this optimization can be applied to your application with 1 being the least
aggressive and 7 being the most aggressive level.
Possible values:
- fstruct-layout=1: enables structure peeling.
- fstruct-layout=2: enables structure peeling and selectively compresses self-referential pointers in these
structures to 32-bit pointers wherever safe.
- fstruct-layout=3: enables structure peeling and selectively compresses self-referential pointers in these
structures to 16-bit pointers wherever safe.
- fstruct-layout=4: enables structure peeling, pointer compression as in level 2 and further enables
compression of structure fields which are of integer type. This is performed under a strict safety check.
- fstruct-layout=5: enables structure peeling, pointer compression as in level 3 and further enables compression
of structure fields which are of integer type. This is performed under a strict safety check.
- fstruct-layout=6: enables structure peeling, pointer compression as in level 2 and further enables compression
of structure fields which are of type 64-bit 'signed int' or 'unsigned Int'. The user needs to ensure that the values
assigned to 64-bit 'signed int' fields are in range -(2^31 - 1) to +(2^31 - 1) and 64-bit 'unsigned int' fields are in
range 0 to +(2^31 - 1), otherwise, incorrect results may be obtained. This compression is performed without considering
any safety analysis and so the user needs to ensure the safety based on the program compiled.
- fstruct-layout=7: enables structure peeling, pointer compression as in level 3 and further enables compression
of structure fields which are of type 64-bit 'signed int' or 'unsigned Int'. The user needs to ensure that the values
assigned to 64-bit 'signed int' fields are in range -(2^31 - 1) to +(2^31 - 1) and 64-bit 'unsigned int' field are in
range 0 to +(2^31 - 1) , otherwise, incorrect results may be obtained. This compression is performed without considering
any safety analysis and so the user needs to ensure the safety based on the program compiled.
Note:
fstruct-layout=4 and fstruct-layout=5 are derived from fstruct-layout=2 and fstruct-layout=3 respectively with the added
feature of safe compression of integer fields in structures. Going from fstruct-layout=4 to fstruct-layout=5 may result
in higher performance if the pointer values are such that the pointers can be compressed to 16-bits.
fstruct-layout=6 and fstruct-layout=7 are derived from fstruct-layout=2 and fstruct-layout=3 respectively with the added
feature of compression of integer fields in structures. These are similar to fstruct-layout=4 and fstruct-layout=5, but
here, the integer fields of the structures are always compressed from 64-bits to 32-bits without any safety guarantee.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
- -m64
- FC, LD
-
Generate code for a 64-bit environment. The 64-bit environment sets int to 32 bits and long and
pointer to 64 bits and generates code for AMD's x86-64 architecture. The compiler generates AMD64, INTEL64,
x86-64 64-bit ABI. The default on a 32-bit host is 32-bit ABI. The default on a 64-bit host is 64-bit ABI if the target
platform specified is 64-bit, otherwise the default is 32-bit.
-
-
-
-
-
-
-
-
-
-
- -O3
- FOPTIMIZE
-
Like -O2, except that it enables optimizations that take longer to perform or that may generate larger code (in
an attempt to make the program run faster).
If multiple "O" options are used, with or without level numbers, the last such option is the one that is effective.
- Includes:
-
- -march=znver3
- FOPTIMIZE
-
Specify that Clang should generate code for a specific processor family member and later. For example, if you specify
-march=znver1, the compiler is allowed to generate instructions that are valid on AMD Zen processors, but
which may not exist on earlier products.
-
-
- -ffast-math
- FOPTIMIZE
-
Enables a range of optimizations that provide faster, though sometimes less precise, mathematical operations that may
not conform to the IEEE-754 specifications. When this option is specified, the __STDC_IEC_559__ macro is
ignored even if set by the system headers.
-
- -Mrecursive
- FOPTIMIZE
-
Allocate local variables on the stack, thus allowing recursion.
SAVEd, data-initialized, or namelist members are always allocated
statically, regardless of the setting of this switch.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
- -m64
- CC, FC, LD
-
Generate code for a 64-bit environment. The 64-bit environment sets int to 32 bits and long and
pointer to 64 bits and generates code for AMD's x86-64 architecture. The compiler generates AMD64, INTEL64,
x86-64 64-bit ABI. The default on a 32-bit host is 32-bit ABI. The default on a 64-bit host is 64-bit ABI if the target
platform specified is 64-bit, otherwise the default is 32-bit.
-
-
-
-
-
-
-
-
-
- -O3
- COPTIMIZE, FOPTIMIZE
-
Like -O2, except that it enables optimizations that take longer to perform or that may generate larger code (in
an attempt to make the program run faster).
If multiple "O" options are used, with or without level numbers, the last such option is the one that is effective.
- Includes:
-
- -march=znver3
- COPTIMIZE, FOPTIMIZE
-
Specify that Clang should generate code for a specific processor family member and later. For example, if you specify
-march=znver1, the compiler is allowed to generate instructions that are valid on AMD Zen processors, but
which may not exist on earlier products.
-
-
- -ffast-math
- COPTIMIZE, FOPTIMIZE
-
Enables a range of optimizations that provide faster, though sometimes less precise, mathematical operations that may
not conform to the IEEE-754 specifications. When this option is specified, the __STDC_IEC_559__ macro is
ignored even if set by the system headers.
-
-
- -fstruct-layout=5
- COPTIMIZE
-
Analyzes the whole program to determine if the structures in the code can be peeled and if pointer or integer fields in
the structure can be compressed. If feasible, this optimization transforms the code to enable these improvements. This
transformation is likely to improve cache utilization and memory bandwidth. This, in turn, is expected to improve the
scalability of programs executed on multiple cores.
This is effective only under -flto as whole program analysis is required to perform this optimization. You can choose
different levels of aggressiveness with which this optimization can be applied to your application with 1 being the least
aggressive and 7 being the most aggressive level.
Possible values:
- fstruct-layout=1: enables structure peeling.
- fstruct-layout=2: enables structure peeling and selectively compresses self-referential pointers in these
structures to 32-bit pointers wherever safe.
- fstruct-layout=3: enables structure peeling and selectively compresses self-referential pointers in these
structures to 16-bit pointers wherever safe.
- fstruct-layout=4: enables structure peeling, pointer compression as in level 2 and further enables
compression of structure fields which are of integer type. This is performed under a strict safety check.
- fstruct-layout=5: enables structure peeling, pointer compression as in level 3 and further enables compression
of structure fields which are of integer type. This is performed under a strict safety check.
- fstruct-layout=6: enables structure peeling, pointer compression as in level 2 and further enables compression
of structure fields which are of type 64-bit 'signed int' or 'unsigned Int'. The user needs to ensure that the values
assigned to 64-bit 'signed int' fields are in range -(2^31 - 1) to +(2^31 - 1) and 64-bit 'unsigned int' fields are in
range 0 to +(2^31 - 1), otherwise, incorrect results may be obtained. This compression is performed without considering
any safety analysis and so the user needs to ensure the safety based on the program compiled.
- fstruct-layout=7: enables structure peeling, pointer compression as in level 3 and further enables compression
of structure fields which are of type 64-bit 'signed int' or 'unsigned Int'. The user needs to ensure that the values
assigned to 64-bit 'signed int' fields are in range -(2^31 - 1) to +(2^31 - 1) and 64-bit 'unsigned int' field are in
range 0 to +(2^31 - 1) , otherwise, incorrect results may be obtained. This compression is performed without considering
any safety analysis and so the user needs to ensure the safety based on the program compiled.
Note:
fstruct-layout=4 and fstruct-layout=5 are derived from fstruct-layout=2 and fstruct-layout=3 respectively with the added
feature of safe compression of integer fields in structures. Going from fstruct-layout=4 to fstruct-layout=5 may result
in higher performance if the pointer values are such that the pointers can be compressed to 16-bits.
fstruct-layout=6 and fstruct-layout=7 are derived from fstruct-layout=2 and fstruct-layout=3 respectively with the added
feature of compression of integer fields in structures. These are similar to fstruct-layout=4 and fstruct-layout=5, but
here, the integer fields of the structures are always compressed from 64-bits to 32-bits without any safety guarantee.
-
-
-
-
-
-
-
-
-
-
-
- -Mrecursive
- FOPTIMIZE
-
Allocate local variables on the stack, thus allowing recursion.
SAVEd, data-initialized, or namelist members are always allocated
statically, regardless of the setting of this switch.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
- -m64
- CC, CXX, FC, LD
-
Generate code for a 64-bit environment. The 64-bit environment sets int to 32 bits and long and
pointer to 64 bits and generates code for AMD's x86-64 architecture. The compiler generates AMD64, INTEL64,
x86-64 64-bit ABI. The default on a 32-bit host is 32-bit ABI. The default on a 64-bit host is 64-bit ABI if the target
platform specified is 64-bit, otherwise the default is 32-bit.
-
-
-
-
-
-
-
-
-
- -O3
- COPTIMIZE, CXXOPTIMIZE, FOPTIMIZE
-
Like -O2, except that it enables optimizations that take longer to perform or that may generate larger code (in
an attempt to make the program run faster).
If multiple "O" options are used, with or without level numbers, the last such option is the one that is effective.
- Includes:
-
- -march=znver3
- COPTIMIZE, CXXOPTIMIZE, FOPTIMIZE
-
Specify that Clang should generate code for a specific processor family member and later. For example, if you specify
-march=znver1, the compiler is allowed to generate instructions that are valid on AMD Zen processors, but
which may not exist on earlier products.
-
-
- -ffast-math
- COPTIMIZE, CXXOPTIMIZE, FOPTIMIZE
-
Enables a range of optimizations that provide faster, though sometimes less precise, mathematical operations that may
not conform to the IEEE-754 specifications. When this option is specified, the __STDC_IEC_559__ macro is
ignored even if set by the system headers.
-
-
- -fstruct-layout=5
- COPTIMIZE
-
Analyzes the whole program to determine if the structures in the code can be peeled and if pointer or integer fields in
the structure can be compressed. If feasible, this optimization transforms the code to enable these improvements. This
transformation is likely to improve cache utilization and memory bandwidth. This, in turn, is expected to improve the
scalability of programs executed on multiple cores.
This is effective only under -flto as whole program analysis is required to perform this optimization. You can choose
different levels of aggressiveness with which this optimization can be applied to your application with 1 being the least
aggressive and 7 being the most aggressive level.
Possible values:
- fstruct-layout=1: enables structure peeling.
- fstruct-layout=2: enables structure peeling and selectively compresses self-referential pointers in these
structures to 32-bit pointers wherever safe.
- fstruct-layout=3: enables structure peeling and selectively compresses self-referential pointers in these
structures to 16-bit pointers wherever safe.
- fstruct-layout=4: enables structure peeling, pointer compression as in level 2 and further enables
compression of structure fields which are of integer type. This is performed under a strict safety check.
- fstruct-layout=5: enables structure peeling, pointer compression as in level 3 and further enables compression
of structure fields which are of integer type. This is performed under a strict safety check.
- fstruct-layout=6: enables structure peeling, pointer compression as in level 2 and further enables compression
of structure fields which are of type 64-bit 'signed int' or 'unsigned Int'. The user needs to ensure that the values
assigned to 64-bit 'signed int' fields are in range -(2^31 - 1) to +(2^31 - 1) and 64-bit 'unsigned int' fields are in
range 0 to +(2^31 - 1), otherwise, incorrect results may be obtained. This compression is performed without considering
any safety analysis and so the user needs to ensure the safety based on the program compiled.
- fstruct-layout=7: enables structure peeling, pointer compression as in level 3 and further enables compression
of structure fields which are of type 64-bit 'signed int' or 'unsigned Int'. The user needs to ensure that the values
assigned to 64-bit 'signed int' fields are in range -(2^31 - 1) to +(2^31 - 1) and 64-bit 'unsigned int' field are in
range 0 to +(2^31 - 1) , otherwise, incorrect results may be obtained. This compression is performed without considering
any safety analysis and so the user needs to ensure the safety based on the program compiled.
Note:
fstruct-layout=4 and fstruct-layout=5 are derived from fstruct-layout=2 and fstruct-layout=3 respectively with the added
feature of safe compression of integer fields in structures. Going from fstruct-layout=4 to fstruct-layout=5 may result
in higher performance if the pointer values are such that the pointers can be compressed to 16-bits.
fstruct-layout=6 and fstruct-layout=7 are derived from fstruct-layout=2 and fstruct-layout=3 respectively with the added
feature of compression of integer fields in structures. These are similar to fstruct-layout=4 and fstruct-layout=5, but
here, the integer fields of the structures are always compressed from 64-bits to 32-bits without any safety guarantee.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
- -mllvm -aggressive-loop-unswitch
- CXXOPTIMIZE
-
This option enables aggressive loop unswitching heuristic (including -enable-partial-unswitch)
based on the usage of the branch conditional values. Loop unswitching leads to code-bloat. Code-bloat can be
minimized if the hoisted condition is executed more often. This heuristic prioritizes the conditions based
on the number of times they are used within the loop. The heuristic can be controlled with the following options:
- -unswitch-identical-branches-min-count=<n>
Enables unswitching of a loop with respect to a branch conditional value (B), where B appears in at least
<n> compares in the loop. This option is enabled with -aggressive-loop-unswitch. Default value is 3.
Usage: -mllvm -aggressive-loop-unswitch -mllvm -unswitch-identical-branches-min-count=<n>
where n is a positive integer and lower value of <n> facilitates more unswitching
- -unswitch-identical-branches-max-count=<n>
Enables unswitching of a loop with respect to a branch conditional value (B), where B appears in at most
<n> compares in the loop. This option is enabled with -aggressive-loop-unswitch. Default value is 6.
Usage: -mllvm -aggressive-loop-unswitch -mllvm -unswitch-identical-branches-max-count=<n>
where n is a positive integer and higher value of <n> facilitates more unswitching
Note: These options may facilitate more unswitching in some of the workloads. Since loop-unswitching inherently leads
to code bloat, facilitating more unswitching may significantly increase the code size and hence may also lead to longer
compilation times.
- Includes:
-
-
-
-
- -Mrecursive
- FOPTIMIZE
-
Allocate local variables on the stack, thus allowing recursion.
SAVEd, data-initialized, or namelist members are always allocated
statically, regardless of the setting of this switch.
-
-
-
-
-
-
-
-
-
-
-
-
Peak Optimization Flags
-
- -m64
- CC, LD
-
Generate code for a 64-bit environment. The 64-bit environment sets int to 32 bits and long and
pointer to 64 bits and generates code for AMD's x86-64 architecture. The compiler generates AMD64, INTEL64,
x86-64 64-bit ABI. The default on a 32-bit host is 32-bit ABI. The default on a 64-bit host is 64-bit ABI if the target
platform specified is 64-bit, otherwise the default is 32-bit.
-
-
-
-
-
-
-
- -march=znver3
- COPTIMIZE
-
Specify that Clang should generate code for a specific processor family member and later. For example, if you specify
-march=znver1, the compiler is allowed to generate instructions that are valid on AMD Zen processors, but
which may not exist on earlier products.
-
-
- -ffast-math
- COPTIMIZE
-
Enables a range of optimizations that provide faster, though sometimes less precise, mathematical operations that may
not conform to the IEEE-754 specifications. When this option is specified, the __STDC_IEC_559__ macro is
ignored even if set by the system headers.
-
-
- -fstruct-layout=5
- COPTIMIZE
-
Analyzes the whole program to determine if the structures in the code can be peeled and if pointer or integer fields in
the structure can be compressed. If feasible, this optimization transforms the code to enable these improvements. This
transformation is likely to improve cache utilization and memory bandwidth. This, in turn, is expected to improve the
scalability of programs executed on multiple cores.
This is effective only under -flto as whole program analysis is required to perform this optimization. You can choose
different levels of aggressiveness with which this optimization can be applied to your application with 1 being the least
aggressive and 7 being the most aggressive level.
Possible values:
- fstruct-layout=1: enables structure peeling.
- fstruct-layout=2: enables structure peeling and selectively compresses self-referential pointers in these
structures to 32-bit pointers wherever safe.
- fstruct-layout=3: enables structure peeling and selectively compresses self-referential pointers in these
structures to 16-bit pointers wherever safe.
- fstruct-layout=4: enables structure peeling, pointer compression as in level 2 and further enables
compression of structure fields which are of integer type. This is performed under a strict safety check.
- fstruct-layout=5: enables structure peeling, pointer compression as in level 3 and further enables compression
of structure fields which are of integer type. This is performed under a strict safety check.
- fstruct-layout=6: enables structure peeling, pointer compression as in level 2 and further enables compression
of structure fields which are of type 64-bit 'signed int' or 'unsigned Int'. The user needs to ensure that the values
assigned to 64-bit 'signed int' fields are in range -(2^31 - 1) to +(2^31 - 1) and 64-bit 'unsigned int' fields are in
range 0 to +(2^31 - 1), otherwise, incorrect results may be obtained. This compression is performed without considering
any safety analysis and so the user needs to ensure the safety based on the program compiled.
- fstruct-layout=7: enables structure peeling, pointer compression as in level 3 and further enables compression
of structure fields which are of type 64-bit 'signed int' or 'unsigned Int'. The user needs to ensure that the values
assigned to 64-bit 'signed int' fields are in range -(2^31 - 1) to +(2^31 - 1) and 64-bit 'unsigned int' field are in
range 0 to +(2^31 - 1) , otherwise, incorrect results may be obtained. This compression is performed without considering
any safety analysis and so the user needs to ensure the safety based on the program compiled.
Note:
fstruct-layout=4 and fstruct-layout=5 are derived from fstruct-layout=2 and fstruct-layout=3 respectively with the added
feature of safe compression of integer fields in structures. Going from fstruct-layout=4 to fstruct-layout=5 may result
in higher performance if the pointer values are such that the pointers can be compressed to 16-bits.
fstruct-layout=6 and fstruct-layout=7 are derived from fstruct-layout=2 and fstruct-layout=3 respectively with the added
feature of compression of integer fields in structures. These are similar to fstruct-layout=4 and fstruct-layout=5, but
here, the integer fields of the structures are always compressed from 64-bits to 32-bits without any safety guarantee.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
- -m64
- CC, LD
-
Generate code for a 64-bit environment. The 64-bit environment sets int to 32 bits and long and
pointer to 64 bits and generates code for AMD's x86-64 architecture. The compiler generates AMD64, INTEL64,
x86-64 64-bit ABI. The default on a 32-bit host is 32-bit ABI. The default on a 64-bit host is 64-bit ABI if the target
platform specified is 64-bit, otherwise the default is 32-bit.
-
-
-
-
-
-
- -march=znver3
- COPTIMIZE
-
Specify that Clang should generate code for a specific processor family member and later. For example, if you specify
-march=znver1, the compiler is allowed to generate instructions that are valid on AMD Zen processors, but
which may not exist on earlier products.
-
-
- -ffast-math
- COPTIMIZE
-
Enables a range of optimizations that provide faster, though sometimes less precise, mathematical operations that may
not conform to the IEEE-754 specifications. When this option is specified, the __STDC_IEC_559__ macro is
ignored even if set by the system headers.
-
-
- -fstruct-layout=5
- COPTIMIZE
-
Analyzes the whole program to determine if the structures in the code can be peeled and if pointer or integer fields in
the structure can be compressed. If feasible, this optimization transforms the code to enable these improvements. This
transformation is likely to improve cache utilization and memory bandwidth. This, in turn, is expected to improve the
scalability of programs executed on multiple cores.
This is effective only under -flto as whole program analysis is required to perform this optimization. You can choose
different levels of aggressiveness with which this optimization can be applied to your application with 1 being the least
aggressive and 7 being the most aggressive level.
Possible values:
- fstruct-layout=1: enables structure peeling.
- fstruct-layout=2: enables structure peeling and selectively compresses self-referential pointers in these
structures to 32-bit pointers wherever safe.
- fstruct-layout=3: enables structure peeling and selectively compresses self-referential pointers in these
structures to 16-bit pointers wherever safe.
- fstruct-layout=4: enables structure peeling, pointer compression as in level 2 and further enables
compression of structure fields which are of integer type. This is performed under a strict safety check.
- fstruct-layout=5: enables structure peeling, pointer compression as in level 3 and further enables compression
of structure fields which are of integer type. This is performed under a strict safety check.
- fstruct-layout=6: enables structure peeling, pointer compression as in level 2 and further enables compression
of structure fields which are of type 64-bit 'signed int' or 'unsigned Int'. The user needs to ensure that the values
assigned to 64-bit 'signed int' fields are in range -(2^31 - 1) to +(2^31 - 1) and 64-bit 'unsigned int' fields are in
range 0 to +(2^31 - 1), otherwise, incorrect results may be obtained. This compression is performed without considering
any safety analysis and so the user needs to ensure the safety based on the program compiled.
- fstruct-layout=7: enables structure peeling, pointer compression as in level 3 and further enables compression
of structure fields which are of type 64-bit 'signed int' or 'unsigned Int'. The user needs to ensure that the values
assigned to 64-bit 'signed int' fields are in range -(2^31 - 1) to +(2^31 - 1) and 64-bit 'unsigned int' field are in
range 0 to +(2^31 - 1) , otherwise, incorrect results may be obtained. This compression is performed without considering
any safety analysis and so the user needs to ensure the safety based on the program compiled.
Note:
fstruct-layout=4 and fstruct-layout=5 are derived from fstruct-layout=2 and fstruct-layout=3 respectively with the added
feature of safe compression of integer fields in structures. Going from fstruct-layout=4 to fstruct-layout=5 may result
in higher performance if the pointer values are such that the pointers can be compressed to 16-bits.
fstruct-layout=6 and fstruct-layout=7 are derived from fstruct-layout=2 and fstruct-layout=3 respectively with the added
feature of compression of integer fields in structures. These are similar to fstruct-layout=4 and fstruct-layout=5, but
here, the integer fields of the structures are always compressed from 64-bits to 32-bits without any safety guarantee.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
- -m64
- FC, LD
-
Generate code for a 64-bit environment. The 64-bit environment sets int to 32 bits and long and
pointer to 64 bits and generates code for AMD's x86-64 architecture. The compiler generates AMD64, INTEL64,
x86-64 64-bit ABI. The default on a 32-bit host is 32-bit ABI. The default on a 64-bit host is 64-bit ABI if the target
platform specified is 64-bit, otherwise the default is 32-bit.
-
-
-
-
-
-
-
-
-
- -march=znver3
- FOPTIMIZE
-
Specify that Clang should generate code for a specific processor family member and later. For example, if you specify
-march=znver1, the compiler is allowed to generate instructions that are valid on AMD Zen processors, but
which may not exist on earlier products.
-
-
- -ffast-math
- FOPTIMIZE
-
Enables a range of optimizations that provide faster, though sometimes less precise, mathematical operations that may
not conform to the IEEE-754 specifications. When this option is specified, the __STDC_IEC_559__ macro is
ignored even if set by the system headers.
-
- -Mrecursive
- FOPTIMIZE
-
Allocate local variables on the stack, thus allowing recursion.
SAVEd, data-initialized, or namelist members are always allocated
statically, regardless of the setting of this switch.
-
-
-
-
-
-
-
-
-
-
-
- -m64
- CC, FC, LD
-
Generate code for a 64-bit environment. The 64-bit environment sets int to 32 bits and long and
pointer to 64 bits and generates code for AMD's x86-64 architecture. The compiler generates AMD64, INTEL64,
x86-64 64-bit ABI. The default on a 32-bit host is 32-bit ABI. The default on a 64-bit host is 64-bit ABI if the target
platform specified is 64-bit, otherwise the default is 32-bit.
-
-
-
-
-
-
-
-
-
- -march=znver3
- COPTIMIZE, FOPTIMIZE
-
Specify that Clang should generate code for a specific processor family member and later. For example, if you specify
-march=znver1, the compiler is allowed to generate instructions that are valid on AMD Zen processors, but
which may not exist on earlier products.
-
-
- -ffast-math
- COPTIMIZE, FOPTIMIZE
-
Enables a range of optimizations that provide faster, though sometimes less precise, mathematical operations that may
not conform to the IEEE-754 specifications. When this option is specified, the __STDC_IEC_559__ macro is
ignored even if set by the system headers.
-
-
- -fstruct-layout=5
- COPTIMIZE
-
Analyzes the whole program to determine if the structures in the code can be peeled and if pointer or integer fields in
the structure can be compressed. If feasible, this optimization transforms the code to enable these improvements. This
transformation is likely to improve cache utilization and memory bandwidth. This, in turn, is expected to improve the
scalability of programs executed on multiple cores.
This is effective only under -flto as whole program analysis is required to perform this optimization. You can choose
different levels of aggressiveness with which this optimization can be applied to your application with 1 being the least
aggressive and 7 being the most aggressive level.
Possible values:
- fstruct-layout=1: enables structure peeling.
- fstruct-layout=2: enables structure peeling and selectively compresses self-referential pointers in these
structures to 32-bit pointers wherever safe.
- fstruct-layout=3: enables structure peeling and selectively compresses self-referential pointers in these
structures to 16-bit pointers wherever safe.
- fstruct-layout=4: enables structure peeling, pointer compression as in level 2 and further enables
compression of structure fields which are of integer type. This is performed under a strict safety check.
- fstruct-layout=5: enables structure peeling, pointer compression as in level 3 and further enables compression
of structure fields which are of integer type. This is performed under a strict safety check.
- fstruct-layout=6: enables structure peeling, pointer compression as in level 2 and further enables compression
of structure fields which are of type 64-bit 'signed int' or 'unsigned Int'. The user needs to ensure that the values
assigned to 64-bit 'signed int' fields are in range -(2^31 - 1) to +(2^31 - 1) and 64-bit 'unsigned int' fields are in
range 0 to +(2^31 - 1), otherwise, incorrect results may be obtained. This compression is performed without considering
any safety analysis and so the user needs to ensure the safety based on the program compiled.
- fstruct-layout=7: enables structure peeling, pointer compression as in level 3 and further enables compression
of structure fields which are of type 64-bit 'signed int' or 'unsigned Int'. The user needs to ensure that the values
assigned to 64-bit 'signed int' fields are in range -(2^31 - 1) to +(2^31 - 1) and 64-bit 'unsigned int' field are in
range 0 to +(2^31 - 1) , otherwise, incorrect results may be obtained. This compression is performed without considering
any safety analysis and so the user needs to ensure the safety based on the program compiled.
Note:
fstruct-layout=4 and fstruct-layout=5 are derived from fstruct-layout=2 and fstruct-layout=3 respectively with the added
feature of safe compression of integer fields in structures. Going from fstruct-layout=4 to fstruct-layout=5 may result
in higher performance if the pointer values are such that the pointers can be compressed to 16-bits.
fstruct-layout=6 and fstruct-layout=7 are derived from fstruct-layout=2 and fstruct-layout=3 respectively with the added
feature of compression of integer fields in structures. These are similar to fstruct-layout=4 and fstruct-layout=5, but
here, the integer fields of the structures are always compressed from 64-bits to 32-bits without any safety guarantee.
-
-
-
-
-
-
-
-
-
-
-
- -O3
- FOPTIMIZE
-
Like -O2, except that it enables optimizations that take longer to perform or that may generate larger code (in
an attempt to make the program run faster).
If multiple "O" options are used, with or without level numbers, the last such option is the one that is effective.
- Includes:
-
- -Mrecursive
- FOPTIMIZE
-
Allocate local variables on the stack, thus allowing recursion.
SAVEd, data-initialized, or namelist members are always allocated
statically, regardless of the setting of this switch.
-
-
-
-
-
-
-
-
-
-
-
-
- -m64
- CC, FC, LD
-
Generate code for a 64-bit environment. The 64-bit environment sets int to 32 bits and long and
pointer to 64 bits and generates code for AMD's x86-64 architecture. The compiler generates AMD64, INTEL64,
x86-64 64-bit ABI. The default on a 32-bit host is 32-bit ABI. The default on a 64-bit host is 64-bit ABI if the target
platform specified is 64-bit, otherwise the default is 32-bit.
-
-
-
-
-
-
-
-
-
- -march=znver3
- COPTIMIZE, FOPTIMIZE
-
Specify that Clang should generate code for a specific processor family member and later. For example, if you specify
-march=znver1, the compiler is allowed to generate instructions that are valid on AMD Zen processors, but
which may not exist on earlier products.
-
-
- -ffast-math
- COPTIMIZE, FOPTIMIZE
-
Enables a range of optimizations that provide faster, though sometimes less precise, mathematical operations that may
not conform to the IEEE-754 specifications. When this option is specified, the __STDC_IEC_559__ macro is
ignored even if set by the system headers.
-
-
- -fstruct-layout=5
- COPTIMIZE
-
Analyzes the whole program to determine if the structures in the code can be peeled and if pointer or integer fields in
the structure can be compressed. If feasible, this optimization transforms the code to enable these improvements. This
transformation is likely to improve cache utilization and memory bandwidth. This, in turn, is expected to improve the
scalability of programs executed on multiple cores.
This is effective only under -flto as whole program analysis is required to perform this optimization. You can choose
different levels of aggressiveness with which this optimization can be applied to your application with 1 being the least
aggressive and 7 being the most aggressive level.
Possible values:
- fstruct-layout=1: enables structure peeling.
- fstruct-layout=2: enables structure peeling and selectively compresses self-referential pointers in these
structures to 32-bit pointers wherever safe.
- fstruct-layout=3: enables structure peeling and selectively compresses self-referential pointers in these
structures to 16-bit pointers wherever safe.
- fstruct-layout=4: enables structure peeling, pointer compression as in level 2 and further enables
compression of structure fields which are of integer type. This is performed under a strict safety check.
- fstruct-layout=5: enables structure peeling, pointer compression as in level 3 and further enables compression
of structure fields which are of integer type. This is performed under a strict safety check.
- fstruct-layout=6: enables structure peeling, pointer compression as in level 2 and further enables compression
of structure fields which are of type 64-bit 'signed int' or 'unsigned Int'. The user needs to ensure that the values
assigned to 64-bit 'signed int' fields are in range -(2^31 - 1) to +(2^31 - 1) and 64-bit 'unsigned int' fields are in
range 0 to +(2^31 - 1), otherwise, incorrect results may be obtained. This compression is performed without considering
any safety analysis and so the user needs to ensure the safety based on the program compiled.
- fstruct-layout=7: enables structure peeling, pointer compression as in level 3 and further enables compression
of structure fields which are of type 64-bit 'signed int' or 'unsigned Int'. The user needs to ensure that the values
assigned to 64-bit 'signed int' fields are in range -(2^31 - 1) to +(2^31 - 1) and 64-bit 'unsigned int' field are in
range 0 to +(2^31 - 1) , otherwise, incorrect results may be obtained. This compression is performed without considering
any safety analysis and so the user needs to ensure the safety based on the program compiled.
Note:
fstruct-layout=4 and fstruct-layout=5 are derived from fstruct-layout=2 and fstruct-layout=3 respectively with the added
feature of safe compression of integer fields in structures. Going from fstruct-layout=4 to fstruct-layout=5 may result
in higher performance if the pointer values are such that the pointers can be compressed to 16-bits.
fstruct-layout=6 and fstruct-layout=7 are derived from fstruct-layout=2 and fstruct-layout=3 respectively with the added
feature of compression of integer fields in structures. These are similar to fstruct-layout=4 and fstruct-layout=5, but
here, the integer fields of the structures are always compressed from 64-bits to 32-bits without any safety guarantee.
-
-
-
-
-
-
-
-
-
-
- -Mrecursive
- FOPTIMIZE
-
Allocate local variables on the stack, thus allowing recursion.
SAVEd, data-initialized, or namelist members are always allocated
statically, regardless of the setting of this switch.
-
-
-
-
-
-
-
Implicitly Included Flags
This section contains descriptions of flags that were included implicitly
by other flags, but which do not have a permanent home at SPEC.
-
- -O2
-
Moderate level of optimization which enables most optimizations. This is the default when no "-O" option is
specified, or if no value is specified (i.e. "-O").
If multiple "O" options are used, with or without level numbers, the last such option is the one that is effective.
- Includes:
-
- -O1
-
Somewhere between -O0 and -O2.
If multiple "O" options are used, with or without level numbers, the last such option is the one that is effective.
-
-
- -O3
-
Like -O2, except that it enables optimizations that take longer to perform or that may generate larger code (in
an attempt to make the program run faster).
If multiple "O" options are used, with or without level numbers, the last such option is the one that is effective.
- Includes:
Using numactl to bind processes and memory to cores
For multi-copy runs or single copy runs on systems with multiple sockets, it is advantageous to bind a process to a
particular core. Otherwise, the OS may arbitrarily move your process from one core to another. This can affect
performance. To help, SPEC allows the use of a "submit" command where users can specify a utility to use to bind
processes. We have found the utility 'numactl' to be the best choice.
numactl runs processes with a specific NUMA scheduling or memory placement policy. The policy is set for a
command and inherited by all of its children. The numactl flag "--physcpubind" specifies
which core(s) to bind the process. "-l" instructs numactl to keep a process's memory on the
local node while "-m" specifies which node(s) to place a process's memory. For full details on using
numactl, please refer to your Linux documentation, 'man numactl'
Note that some older versions of numactl incorrectly interpret application arguments as its own. For
example, with the command "numactl --physcpubind=0 -l a.out -m a", numactl will interpret
a.out's "-m" option as its own "-m" option. To work around this problem, we put
the command to be run in a shell script and then run the shell script using numactl. For example:
"echo 'a.out -m a' > run.sh ; numactl --physcpubind=0 bash run.sh"
Transparent Huge Pages (THP)
THP is an abstraction layer that automates most aspects of creating, managing, and using huge pages. THP is designed
to hide much of the complexity in using huge pages from system administrators and developers, as normal huge pages
must be assigned at boot time, can be difficult to manage manually, and often require significant changes to code in
order to be used effectively. Most recent Linux OS releases have THP enabled by default.
ulimit -s <n>
Sets the stack size to n kbytes, or unlimited to allow the stack size to grow without limit.
ulimit -l <n>
Sets the maximum size of memory that may be locked into physical memory.
powersave -f (on SuSE)
Makes the powersave daemon set the CPUs to the highest supported frequency.
/etc/init.d/cpuspeed stop (on Red Hat)
Disables the cpu frequency scaling program in order to set the CPUs to the highest supported frequency.
LD_LIBRARY_PATH
An environment variable that indicates the location in the filesystem of bundled libraries to use when running the
benchmark binaries.
kernel/randomize_va_space
This option can be used to select the type of process address space randomization that is used in the system, for
architectures that support this feature.
- 0 - Turn the process address space randomization off. This is the default for architectures that do not support
this feature anyway, and kernels that are booted with the "
norandmaps" parameter.
- 1 - Make the addresses of mmap base, stack and VDSO page randomized. This, among other things, implies that
shared libraries will be loaded to random addresses. Also for PIE-linked binaries, the location of code start is
randomized. This is the default if the
CONFIG_COMPAT_BRK option is enabled.
- 2 - Additionally enable heap randomization. This is the default if
CONFIG_COMPAT_BRK is
disabled.
MALLOC_CONF
An environment variable set to tune the jemalloc allocation strategy during the execution of the binaries. This
environment variable setting is not needed when building the binaries on the system under test.
PGHPF_ZMEM
An environment variable used to initialize the allocated memory. Setting PGHPF_ZMEM to "Yes" has the effect of
initializing all allocated memory to zero.
GOMP_CPU_AFFINITY
This environment variable is used to set the thread affinity for threads spawned by OpenMP.
OMP_DYNAMIC
This environment variable is defined as part of the OpenMP standard.
Setting it to "false" prevents the OpenMP runtime from dynamically adjusting the number of threads to use for parallel
execution.
For more information, see chapter 4 ("Environment Variables") in the
OpenMP 4.5 Specification.
OMP_SCHEDULE
This environment variable is defined as part of the OpenMP standard.
Setting it to "static" causes loop iterations to be assigned to threads in round-robin fashion in the order of the thread
number.
For more information, see chapter 4 ("Environment Variables") in the
OpenMP 4.5 Specification.
OMP_STACKSIZE
This environment variable is defined as part of the OpenMP standard and controls the size of the stack for threads created
by OpenMP.
For more information, see chapter 4 ("Environment Variables") in the
OpenMP 4.5 Specification.
OMP_THREAD_LIMIT
This environment variable is defined as part of the OpenMP standard and limits the maximum number of OpenMP threads that
can be created.
For more information, see chapter 4 ("Environment Variables") in the
OpenMP 4.5 Specification.
- cpupower:
-
The OS 'cpupower' utility is used to change CPU power governors settings. Available settings are:
- Performance: Run the CPU at the maximum frequency.
- powersave(default): Run the CPU at the minimum frequency.
- ondemand: Scales the frequency dynamically according to current load. Jumps to the highest frequency and then possibly back off as the idle time increases.
- kernel.randomize_va_space (ASLR)
-
This setting can be used to select the type of process address space randomization.
Defaults differ based on whether the architecture supports ASLR, whether the kernel
was built with the CONFIG_COMPAT_BRK option or not, or the kernel boot options used.
Possible settings:
- 0: Turn process address space randomization off.
- 1: Randomize addresses of mmap base, stack, and VDSO pages.
- 2: Additionally randomize the heap. (This is probably the default.)
Disabling ASLR can make process execution more deterministic and runtimes more consistent.
For more information see the randomize_va_space entry in the
Linux sysctl documentation.
- Transparent Hugepages (THP)
-
THP is an abstraction layer that automates most aspects of creating, managing,
and using huge pages. It is designed to hide much of the complexity in using
huge pages from system administrators and developers. Huge pages
increase the memory page size from 4 kilobytes to 2 megabytes. This provides
significant performance advantages on systems with highly contended resources
and large memory workloads. If memory utilization is too high or memory is badly
fragmented which prevents hugepages being allocated, the kernel will assign
smaller 4k pages instead. Most recent Linux OS releases have THP enabled by default.
THP usage is controlled by the sysfs setting /sys/kernel/mm/transparent_hugepage/enabled.
Possible values:
- never: entirely disable THP usage.
- madvise: enable THP usage only inside regions marked MADV_HUGEPAGE using madvise(3).
- always: enable THP usage system-wide. This is the default.
THP creation is controlled by the sysfs setting /sys/kernel/mm/transparent_hugepage/defrag.
Possible values:
- never: if no THP are available to satisfy a request, do not attempt to make any.
- defer: an allocation requesting THP when none are available get normal pages while requesting THP creation in the background.
- defer+madvise: acts like "always", but only for allocations in regions marked MADV_HUGEPAGE using madvise(3); for all other regions it's like "defer".
- madvise: acts like "always", but only for allocations in regions marked MADV_HUGEPAGE using madvise(3). This is the default.
- always: an allocation requesting THP when none are available will stall until some are made.
An application that "always" requests THP often can benefit from waiting for an allocation until those huge pages can be assembled.
For more information see the Linux transparent hugepage documentation.
- Determinism Slider:
-
This BIOS option allows for AGESA determinism to control performance.
- Performance: Provides predictable performance across all processors of the same type.
- Power: Maximizes performance within the power limits defined by cTDP and PPT.
- Auto (Default setting): Use AGESA default value for deterministic performance control.
- cTDP Control:
-
This BIOS option is for "Configurable TDP (cTDP)", it allows user can set customized value for TDP. Available settings are:
- Auto: Use the fused TDP value.
- Manual(Default setting): Let user specifies customized TDP value.
- cTDP:
-
TDP is an acronym for "Thermal Design Power." TDP is the recommended target for power used when designing the cooling capacity for a server.
EPYC processors are able to control this target power consumption within certain limits. This capability is referred to as "configurable TDP" or "cTDP."
cTDP can be used to reduce power consumption for greater efficiency, or in some cases, increase power consumption above the default value to provide additional performance.
cTDP is controlled using a BIOS option.
The default EPYC cTDP value corresponds with the microprocessor's nominal TDP.
The default cTDP value is set at a good balance between performance and energy efficiency.
The EPYC 7763 cTDP can be reduced as low as 225W, which will minimize the power consumption for the processor under load, but at the expense of peak performance.
Increasing the EPYC 7763 cTDP to 280W will maximize peak performance by allowing the CPU to maintain higher dynamic clock speeds, but will make the microprocessor less energy efficient.
Note that at maximum cTDP, the CPU thermal solution must be capable of dissipating at least 280W or the EPYC 7763 processor might engage in thermal throttling under load.
The available cTDP ranges for each EPYC model are in the table below:
| Model | Minimum cTDP | Maximum cTDP |
|---|
| EPYC 7763 | 225 | 280 |
| EPYC 7713 | 225 | 240 |
| EPYC 7713P | 225 | 240 |
| EPYC 7663 | 225 | 240 |
| EPYC 7643 | 225 | 240 |
| EPYC 75F3 | 225 | 280 |
| EPYC 7543 | 225 | 240 |
| EPYC 7543P | 225 | 240 |
| EPYC 7513 | 165 | 200 |
| EPYC 7453 | 225 | 240 |
| EPYC 74F3 | 225 | 240 |
| EPYC 7443 | 165 | 200 |
| EPYC 7443P | 165 | 200 |
| EPYC 7413 | 165 | 200 |
| EPYC 73F3 | 225 | 240 |
| EPYC 7343 | 165 | 200 |
| EPYC 7313 | 155 | 180 |
| EPYC 7313P | 155 | 180 |
| EPYC 72F3 | 165 | 200 |
* cTDP must remain below the thermal solution design parameters or thermal throttling could be frequently encountered.
- Power phase shedding:
-
Power phase shedding allows efficiency optimization of the voltage regulator across the variety of loads, minimizing average energy consumption by optimizing the powertrain for specific load power states.
Values for this BIOS option can be: Enabled/Disabled. Current default is Enabled.
- SVM Mode:
-
This is CPU virtualization function. With SVM enabled you'll be able to install a virtual machine on your system.
Values for this BIOS option can be: Enabled/Disabled. Current default is Enabled.
- SR-IOV support:
-
In virtualization, single root input/output virtualization or SR-IOV is a specification that allows the isolation of the PCI Express resources for manageability and performance reasons.
A single physical PCI Express can be shared on a virtual environment using the SR-IOV specification.
If system has SR-IOV capable PCIe Devices, this option Enables or Disables Single Root IO Virtualization Support. Values for this BIOS option can be: Enabled/Disabled. Current default is Disabled.
- DRAM Scrub time:
-
DRAM scrubbing is a mechanism for the memory controller to periodically read all memory locations and write back corrected data.
The time interval for scrubbing the entire memory can be: Disabled/1 hour/4 hours/8 hours/16 hours/24 hours/48 hours/Auto. Current default is Auto(AGESA default value).
- NUMA nodes per socket:
-
Specifies the number of desired NUMA nodes per populated socket in the system:
- NPS1: Each physical processor is a NUMA node, and memory accesses are interleaved across all memory channels directly connected to the physical processor.
- NPS2: Each physical processor is two NUMA nodes, and memory accesses are interleaved across 4 memory channels.
- NPS4: Each physical processor is four NUMA nodes, and memory accesses are interleaved across 2 memory channels.
- Auto: Use AGESA default value. Current default is NPS1
Current default is Auto.
- APBDIS:
-
Application Power Management (APM) allows the processor to provide maximum performance while remaining within
the specified power delivery and removal envelope. APM dynamically monitors processor activity and generates an
approximation of power consumption. If power consumption exceeds a defined power limit, a P-state limit is applied by
APM hardware to reduce power consumption. APM ensures that average power consumption over a thermally significant
time period remains at or below the defined power limit. Set APBDIS=1 will disable Data Fabric APM and the SOC P-state will be fixed.
Available settings are:
- 0: Disable APBDIS.
- 1: Enable APBDIS.
- Auto (Default setting): Use default value for APBDIS. The current value is 0.
- Fix SOC P-state:
-
To minimize variance or trade-off memory latency versus bandwidth, algorithm performance boost
(APBDIS) can be set and specific hard-fused Data Fabric (SoC) P-states forced for optimized
workloads sensitive to latency or throughput.
Available settings are:
- P0: The highest SOC P-state.
- P1
- P2
- P3: The lowest SOC P-state.
- Auto (Default setting): Use AGESA default value.
- ACPI SRAT L3 Cache as NUMA Domain:
-
Each L3 Cache will be exposed as a NUMA node when enabling ACPI SRAT L3 Cache as a NUMA node.
On a dual processor system, with up to 8 L3 Caches per processor, this setting will expose 16 NUMA domains.
Available settings are:
- Auto (Default setting): Disable this function.
- Enabled: Enable this function.
- Package Power Limit Control:
-
This BIOS option allows user can set customized value for processor package power limit(PPT). Available settings are:
- Auto: Use the fused PPT.
- Manual(Default setting): User can set customized PPT.
- DLWM Support:
-
Dynamic Link Width Management(DLWM) reduces xGMI lane width from x16 to x8 or x2 if xGMI links have limited traffic. DLWM feature is optimized to
trade power between CPU core intensive workloads and I/O bandwidth intensiveworkloads. When link activity is above a threshold, DLWM will
increase lane width from x8 to x16 at the cost of some delay, because the I/O die must disconnect the links, retrain them at the new speed
and release the system back to functionality.
Values for this BIOS option can be: Auto/Enabled/Disabled. Current default is Auto.(Use AGESA default value. Current is Enabled.)
- Engine Boost:
-
ASUS individual feature with the power acceleration design to increase CPU over-all performance. Available settings are: disabled(default) and enabled.
Enable it could improve performance, but comes with more power consumption.
- Package Power Limit:
-
Set customize processor Package Power Limit (PPT) value to be used on all populated processors in the system. Current default value is 240 = Use the 240W PPT value.
***PPT will be used as the ASIC power limit***
- IOMMU:
-
The Input-Output Memory Management Unit(IOMMU) provides several benefits and is required when using x2APIC. Enabling the IOMMU allows devices
(such as the EPYC integrated SATA controller) to present separate IRQs for each attached device instead of one IRQ for the subsystem.
The IOMMU also allows operating systems to provide additional protection for DMA capable I/O devices.
Values for this BIOS option can be: Auto/Enabled/Disabled. Current default is Auto.(Use AGESA default value. Current is Enabled.)
- Memory Interleaving:
-
Memory interleaving is a technique that CPUs use to increase the memory bandwidth available for an
application. Without interleaving, consecutive memory blocks, often cache lines, are read from the
same memory bank. Because of this, software that reads consecutive memory must wait for a
memory transfer to complete before starting the next memory access, reducing throughput and
increasing latency. By enabling memory interleaving, consecutive memory blocks are in different
banks and can all contribute to the overall memory bandwidth, thus increasing throughput and lowering latency.
Values for this BIOS option can be: Auto/Disabled. Current default is Auto.(Use AGESA default value. Current is Enabled.)
For questions about the meanings of these flags, please contact the tester.
For other inquiries, please contact info@spec.org
Copyright 2017-2021 Standard Performance Evaluation Corporation
Tested with SPEC CPU2017 v1.1.8.
Report generated on 2021-07-06 18:41:17 by SPEC CPU2017 flags formatter v5178.
![[benchmark]](https://www.spec.org/auto/cpu2017/images/benchmark.png)