CPU2017 Flag Description
Fusionstor Invento i6000 EPYC (AMD EPYC 9554)
Test sponsored by meganet
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.
-
- 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.
-
- 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.
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.
-
- 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.
-
- 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.
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.
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.
Base Optimization Flags
-
- -m64
- CC, LD
-
Generates 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=znver5
- 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. -march=znver4 enables AVX 512 ISA for Genoa (znver4) processors.
-
-
- -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=7
- COPTIMIZE
-
Analyzes the whole program to determine if the structures in the code can be peeled, if dead or redundant fields can be deleted, and if
the 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. It is expected
to improve the scalability of programs executed on multiple cores.
This is effective only under flto as the 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=0: disables structure peeling (default).
- 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 64-bit integer type to 32-bit 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 64-bit integer type to 32-bit 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 integer type to 16-bit integer type. This is performed under a strict
safety check.
- 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 integer type to 16-bit integer type. This is performed under a strict
safety check.
- fstruct-layout=8: enables structure peeling, pointer compression, 64 bit integer type compression
as in level 6 and creates optimal ordering of peeled structure fields which could improve runtime performance.
- fstruct-layout=9: enables structure peeling, pointer compression, 64 bit integer type compression
as in level 7 and creates optimal ordering of peeled structure fields which could improve runtime performance.
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 64-bit integer fields to 32-bit 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 fstructlayout=3 respectively, with the
added feature of safe compression of 64 bit integer fields to 16 bit integer in structures. Going from fstruct-layout=6
to fstruct-layout=7 may result in higher performance if the pointer values are such that the pointers can be
compressed to 16-bits.
-
-
-
-
-
-
- -zopt
- COPTIMIZE
-
This option enables a subset of scalar, vector and loop transformations including improved variants of loop invariant code motion, SLP and loop vectorizations, loop-fusion, loop-interchange, loop-unswitch, loop tiling and loop distribution.
-
-
-
- -lamdalloc-ext
- EXTRA_CLIBS
-
amdalloc-ext is a AMD's memory allocation library optimized for performance. You can link the library only on Linux platforms. This library provides optimized implementation of allocation routines malloc(), calloc(), realloc() and free(). It is C99 standard compliant. This library is not thread safe. It should not be used in multi threaded application.
-
-
- -m64
- CXX, LD
-
Generates 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.
-
-
-
-
- -Wl,-mllvm -Wl,-do-block-reorder=advanced
- LDCXXFLAGS
-
Block Reordering
Possible values:
- none: No block reorder
- simple: Simple block reorder
- complex: Do block reorder for more complex inputs such as inputs with exception handlers
- advanced: In addition to all cases handled by complex, this option handles more cases
involving operations with side-effects
-
-
- -O3
- CXXOPTIMIZE
-
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=znver5
- CXXOPTIMIZE
-
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. -march=znver4 enables AVX 512 ISA for Genoa (znver4) processors.
-
-
- -ffast-math
- CXXOPTIMIZE
-
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.
-
-
-
-
-
- -zopt
- CXXOPTIMIZE
-
This option enables a subset of scalar, vector and loop transformations including improved variants of loop invariant code motion, SLP and loop vectorizations, loop-fusion, loop-interchange, loop-unswitch, loop tiling and loop distribution.
-
-
-
-
-
- -mllvm -do-block-reorder=advanced
- EXTRA_CXXOPTIMIZE
-
Block Reordering
Possible values:
- none: No block reorder
- simple: Simple block reorder
- complex: Do block reorder for more complex inputs such as inputs with exception handlers
- advanced: In addition to all cases handled by complex, this option handles more cases
involving operations with side-effects
-
-
-
- -lamdalloc-ext
- EXTRA_CXXLIBS
-
amdalloc-ext is a AMD's memory allocation library optimized for performance. You can link the library only on Linux platforms. This library provides optimized implementation of allocation routines malloc(), calloc(), realloc() and free(). It is C99 standard compliant. This library is not thread safe. It should not be used in multi threaded application.
-
-
- -m64
- FC, LD
-
Generates 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=znver5
- 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. -march=znver4 enables AVX 512 ISA for Genoa (znver4) processors.
-
-
- -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.
-
-
-
-
-
-
-
-
-
-
Peak Optimization Flags
-
- -m32
- CC, LD
-
Generates code for a 32-bit environment. The 32-bit environment sets int, long and
pointer to 32 bits and generates code that runs on any i386 system. The compiler generates x86 or IA32
32-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=znver5
- 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. -march=znver4 enables AVX 512 ISA for Genoa (znver4) processors.
-
-
- -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=7
- COPTIMIZE
-
Analyzes the whole program to determine if the structures in the code can be peeled, if dead or redundant fields can be deleted, and if
the 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. It is expected
to improve the scalability of programs executed on multiple cores.
This is effective only under flto as the 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=0: disables structure peeling (default).
- 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 64-bit integer type to 32-bit 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 64-bit integer type to 32-bit 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 integer type to 16-bit integer type. This is performed under a strict
safety check.
- 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 integer type to 16-bit integer type. This is performed under a strict
safety check.
- fstruct-layout=8: enables structure peeling, pointer compression, 64 bit integer type compression
as in level 6 and creates optimal ordering of peeled structure fields which could improve runtime performance.
- fstruct-layout=9: enables structure peeling, pointer compression, 64 bit integer type compression
as in level 7 and creates optimal ordering of peeled structure fields which could improve runtime performance.
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 64-bit integer fields to 32-bit 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 fstructlayout=3 respectively, with the
added feature of safe compression of 64 bit integer fields to 16 bit integer in structures. Going from fstruct-layout=6
to fstruct-layout=7 may result in higher performance if the pointer values are such that the pointers can be
compressed to 16-bits.
-
-
-
-
-
-
- -zopt
- COPTIMIZE
-
This option enables a subset of scalar, vector and loop transformations including improved variants of loop invariant code motion, SLP and loop vectorizations, loop-fusion, loop-interchange, loop-unswitch, loop tiling and loop distribution.
-
- EXTRA_CFLAGS
-
In the 502/602.gcc benchmark description,
"multiple definitions of symbols" is listed under the "Known Portability Issues" section, and this option is one of the
suggested workarounds. This option causes Clang to revert to the same inlining behavior that GCC does when in pre-C99
mode.
-
-
- -m64
- CC, LD
-
Generates 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=znver5
- 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. -march=znver4 enables AVX 512 ISA for Genoa (znver4) processors.
-
-
- -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=7
- COPTIMIZE
-
Analyzes the whole program to determine if the structures in the code can be peeled, if dead or redundant fields can be deleted, and if
the 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. It is expected
to improve the scalability of programs executed on multiple cores.
This is effective only under flto as the 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=0: disables structure peeling (default).
- 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 64-bit integer type to 32-bit 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 64-bit integer type to 32-bit 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 integer type to 16-bit integer type. This is performed under a strict
safety check.
- 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 integer type to 16-bit integer type. This is performed under a strict
safety check.
- fstruct-layout=8: enables structure peeling, pointer compression, 64 bit integer type compression
as in level 6 and creates optimal ordering of peeled structure fields which could improve runtime performance.
- fstruct-layout=9: enables structure peeling, pointer compression, 64 bit integer type compression
as in level 7 and creates optimal ordering of peeled structure fields which could improve runtime performance.
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 64-bit integer fields to 32-bit 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 fstructlayout=3 respectively, with the
added feature of safe compression of 64 bit integer fields to 16 bit integer in structures. Going from fstruct-layout=6
to fstruct-layout=7 may result in higher performance if the pointer values are such that the pointers can be
compressed to 16-bits.
-
-
-
-
-
-
- -zopt
- COPTIMIZE
-
This option enables a subset of scalar, vector and loop transformations including improved variants of loop invariant code motion, SLP and loop vectorizations, loop-fusion, loop-interchange, loop-unswitch, loop tiling and loop distribution.
-
-
-
- EXTRA_CLIBS
-
amdalloc-ext is a AMD's memory allocation library optimized for performance. You can link the library only on Linux platforms. This library provides optimized implementation of allocation routines malloc(), calloc(), realloc() and free(). It is C99 standard compliant. This library is not thread safe. It should not be used in multi threaded application.
-
-
- -m64
- CC, LD
-
Generates 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=znver5
- 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. -march=znver4 enables AVX 512 ISA for Genoa (znver4) processors.
-
-
- -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=7
- COPTIMIZE
-
Analyzes the whole program to determine if the structures in the code can be peeled, if dead or redundant fields can be deleted, and if
the 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. It is expected
to improve the scalability of programs executed on multiple cores.
This is effective only under flto as the 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=0: disables structure peeling (default).
- 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 64-bit integer type to 32-bit 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 64-bit integer type to 32-bit 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 integer type to 16-bit integer type. This is performed under a strict
safety check.
- 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 integer type to 16-bit integer type. This is performed under a strict
safety check.
- fstruct-layout=8: enables structure peeling, pointer compression, 64 bit integer type compression
as in level 6 and creates optimal ordering of peeled structure fields which could improve runtime performance.
- fstruct-layout=9: enables structure peeling, pointer compression, 64 bit integer type compression
as in level 7 and creates optimal ordering of peeled structure fields which could improve runtime performance.
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 64-bit integer fields to 32-bit 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 fstructlayout=3 respectively, with the
added feature of safe compression of 64 bit integer fields to 16 bit integer in structures. Going from fstruct-layout=6
to fstruct-layout=7 may result in higher performance if the pointer values are such that the pointers can be
compressed to 16-bits.
-
-
-
-
-
-
- -zopt
- COPTIMIZE
-
This option enables a subset of scalar, vector and loop transformations including improved variants of loop invariant code motion, SLP and loop vectorizations, loop-fusion, loop-interchange, loop-unswitch, loop tiling and loop distribution.
-
-
-
- EXTRA_CLIBS
-
amdalloc-ext is a AMD's memory allocation library optimized for performance. You can link the library only on Linux platforms. This library provides optimized implementation of allocation routines malloc(), calloc(), realloc() and free(). It is C99 standard compliant. This library is not thread safe. It should not be used in multi threaded application.
-
-
- -m64
- CXX, LD
-
Generates 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.
-
-
-
-
- -Wl,-mllvm -Wl,-do-block-reorder=advanced
- LDCXXFLAGS
-
Block Reordering
Possible values:
- none: No block reorder
- simple: Simple block reorder
- complex: Do block reorder for more complex inputs such as inputs with exception handlers
- advanced: In addition to all cases handled by complex, this option handles more cases
involving operations with side-effects
-
-
- -march=znver5
- CXXOPTIMIZE
-
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. -march=znver4 enables AVX 512 ISA for Genoa (znver4) processors.
-
-
- -ffast-math
- CXXOPTIMIZE
-
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.
-
-
-
-
- -zopt
- CXXOPTIMIZE
-
This option enables a subset of scalar, vector and loop transformations including improved variants of loop invariant code motion, SLP and loop vectorizations, loop-fusion, loop-interchange, loop-unswitch, loop tiling and loop distribution.
-
-
-
-
-
- EXTRA_CXXOPTIMIZE
-
Block Reordering
Possible values:
- none: No block reorder
- simple: Simple block reorder
- complex: Do block reorder for more complex inputs such as inputs with exception handlers
- advanced: In addition to all cases handled by complex, this option handles more cases
involving operations with side-effects
-
-
- EXTRA_CXXLIBS, EXTRA_LIBS
-
amdalloc-ext is a AMD's memory allocation library optimized for performance. You can link the library only on Linux platforms. This library provides optimized implementation of allocation routines malloc(), calloc(), realloc() and free(). It is C99 standard compliant. This library is not thread safe. It should not be used in multi threaded application.
-
-
- -m64
- FC, LD
-
Generates 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=znver5
- 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. -march=znver4 enables AVX 512 ISA for Genoa (znver4) processors.
-
-
- -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.
-
-
-
-
-
-
-
-
-
-
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"
numactl --interleave=all runcpu
numactl --interleave=all runcpu executes the SPEC CPU command runcpu so that memory is consumed across NUMA nodes rather than consumed from a single node. This helps prevent local node out-of-memory conditions which can occur when runcpu is executed without interleaving.
For full details on using numactl, please refer to your Linux documentation, 'man numactl'
Transparent Huge Pages (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 huge pages 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.
The SPEC CPU benchmark codes themselves never explicitly request huge pages, as the mechanism to do that is OS-specific
and can change over time. Libraries such as amdalloc which are used by the benchmarks may explicitly request huge pages,
and use of such libraries can make the "madvise" setting relevant and useful.
When no huge pages are immediately available and one is requested, how the system handles the request for 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 gets 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.
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.
LIBOMP_NUM_HIDDEN_HELPER_THREADS
target nowait is supported via hidden helper task, which is a task not bound to any parallel region. A hidden helper team with a number of threads is created when the first hidden helper task is encountered.
The number of threads can be configured via the environment variable LIBOMP_NUM_HIDDEN_HELPER_THREADS. The default is 8. If LIBOMP_NUM_HIDDEN_HELPER_THREADS is 0, the hidden helper task is disabled and support falls back to a regular OpenMP task. The hidden helper task can also be disabled by setting the environment variable LIBOMP_USE_HIDDEN_HELPER_TASK=OFF.
sysctl -w vm.dirty_ratio=8
Limits dirty cache to 8% of memory.
sysctl -w vm.swappiness=1
Limits swap usage to minimum necessary.
sysctl -w vm.zone_reclaim_mode=1
Frees local node memory first to avoid remote memory usage.
kernel/numa_balancing
This OS setting controls automatic NUMA balancing on memory mapping and process placement.
NUMA balancing incurs overhead for no benefit on workloads that are already bound to NUMA nodes.
Possible settings:
- 0: disables this feature
- 1: enables the feature (this is the default)
For more information see the numa_balancing entry in the
Linux sysctl documentation.
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 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 - Randomize addresses of mmap base, stack, and VDSO pages.
This is the default if the
CONFIG_COMPAT_BRK option is enabled at kernel build time.
- 2 - Additionally enable heap randomization. This is the default if
CONFIG_COMPAT_BRK is
disabled.
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.
vm/drop_caches
The two commands are equivalent:
echo 3> /proc/sys/vm/drop_caches
and
sysctl -w vm.drop_caches=3
Both must be run as root.
The commands are used to free up the filesystem page cache, dentries, and inodes.
Possible settings:
- 1 - Clear pagecache
- 2 - Clear dentries and inodes
- 3 - Clear pagecache, dentries, and inodes
MALLOC_CONF
The amdalloc library is a variant of jemalloc library. The amdalloc
library has tunable parameters, many of which may be changed at run-time via several mechanisms, one of which
is the MALLOC_CONF environment variable. Other methods, as well as the order in which they're referenced,
are detailed in the jemalloc documentation's TUNING section.
The options that can be tuned at run-time are everything in the jemalloc documentation's
MALLCTL NAMESPACE section that begins with
"opt.".
The options that may be encountered in SPEC CPU 2017 results are detailed here:
retain:true - Causes unused virtual memory to
be retained for later reuse rather than discarding it. This is the default for 64-bit Linux.thp:never - Attempts to never utilize huge pages
by using MADV_NOHUGEPAGE on all mappings. This option has no effect except when THP is set to
"madvise".
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.
OS Tuning
setterm:
Used to disable screen blanking on text console:
- "setterm -powersave off -blank 0"
ulimit:
Used to set user limits of system-wide resources. Provides control over resources available to the shell and processes started by it. Some common ulimit commands may include:
- ulimit -s [n | unlimited]: Set the stack size to n kbytes, or unlimited to allow the stack size to grow without limit.
- ulimit -l (number): Set the maximum size that can be locked into memory.
Disabling Linux services:
Certain Linux services may be disabled to minimize tasks that may consume CPU cycles.
irqbalance:
Disabled through "service irqbalance stop". Depending on the workload involved, the irqbalance service reassigns various IRQ's to system CPUs. Though this service might help in some situations, disabling it can also help environments which need to minimize or eliminate latency to more quickly respond to events.
Performance Governors (Linux):
In-kernel CPU frequency governors are pre-configured power schemes for the CPU. The CPUfreq governors use P-states to change frequencies and lower power consumption. The dynamic governors can switch between CPU frequencies, based on CPU utilization to allow for power savings while not sacrificing performance.
Other options beside a generic performance governor can be set, such as the perf-bias:
--perf-bias, -b
On supported Intel processors, this option sets a register which allows the cpupower utility (or other software/firmware) to set a policy that controls the relative importance of performance versus energy savings to the processor. The range of valid numbers is 0-15, where 0 is maximum performance and 15 is maximum energy efficiency.
The processor uses this information in model-specific ways when it must select trade-offs between performance and energy efficiency. This policy hint does not supersede Processor Performance states (P-states) or CPU Idle power states (C-states), but allows software to have influence where it would otherwise be unable to express a preference.
On many Linux systems one can set the perf-bias for all CPUs through the cpupower utility with one of the following commands:
- "cpupower frequency-set -g performance"
- "cpupower -c all set -b 0"
- "cpupower -c all set --perf-bias 0"
- "cpupower set -b 0"
Tuning Kernel parameters:
The following Linux Kernel parameters were tuned to better optimize performance of some areas of the system:
- dirty_background_ratio: Set through "echo 40 > /proc/sys/vm/dirty_background_ratio". This setting can help Linux disk caching and performance by setting the percentage of system memory that can be filled with dirty pages.
- dirty_ratio: Set through "echo 40 > /proc/sys/vm/dirty_ratio". This setting is the absolute maximum amount of system memory that can be filled with dirty pages before everything must get committed to disk.
- swappiness: The swappiness value can range from 1 to 100. A value of 100 will cause the kernel to swap out inactive processes frequently in favor of file system performance, resulting in large disk cache sizes. A value of 1 tells the kernel to only swap processes to disk if absolutely necessary. This can be set through a command like "echo 1 > /proc/sys/vm/swappiness"
- ksm/sleep_millisecs: Set through "echo 200 > /sys/kernel/mm/ksm/sleep_millisecs". This setting controls how many milliseconds the ksmd (KSM daemon) should sleep before the next scan.
- khugepaged/scan_sleep_millisecs: Set through "echo 50000 > /sys/kernel/mm/transparent_hugepage/khugepaged/scan_sleep_millisecs". This setting controls how many milliseconds to wait if khugepaged encounters a hugepage allocation failure to throttle the next allocation attempt.
- numa_balancing: Disabled through "echo 0 > /proc/sys/kernel/numa_balancing". This feature will automatically migrate data on demand so memory nodes are aligned to the local CPU that is accessing data. Depending on the workload involved, enabling this can boost performance if the workload performs well on NUMA hardware. If the workload is statically set to balance between nodes, then this service may not provide a benefit.
- Zone Reclaim Mode: Zone reclaim allows the reclaiming of pages from a zone if the number of free pages falls below a watermark even if other zones still have enough pages available. Reclaiming a page can be more beneficial than taking the performance penalties that are associated with allocating a page on a remote zone, especially for NUMA machines. To tell the kernel to free local node memory rather than grabbing free memory from remote nodes, use a command like "echo 1 > /proc/sys/vm/zone_reclaim_mode"
- max_map_count-n: The maximum number of memory map areas a process may have. Memory map areas are used as a side-effect of calling malloc, directly by mmap and mprotect, and also when loading shared libraries.
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. Transparent Hugepages increase the memory page size from 4 kilobytes to 2 megabytes. Transparent Hugepages provide 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 from being allocated, the kernel will assign smaller 4k pages instead. Most recent Linux OS releases have THP enabled by default.
Linux Huge Page settings:
If you need finer control and manually set the Huge Pages you can follow the below steps:
- Create a mount point for the huge pages: "mkdir /mnt/hugepages"
- The huge page file system needs to be mounted when the systems reboots. Add the following to a system boot configuration file before any services are started: "mount -t hugetlbfs nodev /mnt/hugepages"
- Set vm/nr_hugepages=N in your /etc/sysctl.conf file where N is the maximum number of pages the system may allocate.
- Reboot to have the changes take effect.
Note that further information about huge pages may be found in your Linux documentation file: /usr/src/linux/Documentation/vm/hugetlbpage.txt
Firmware Settings
Power Policy Quick Settings: (Default = Best Performance)
This BIOS option controls the performance or power save setting, user can use this item to change it. Best performance can maximize the performance of the server. Energy efficiency can maximize the power efficiency of the server.
Values for this BIOS setting can be:
- Standard: BIOS default setting.
- Best Performance: Maximize the performance of the server.
- Energy Efficient: Maximize the power efficiency of the server.
SMT Control (Default = Enabled):
This setting controls Simultaneous Multi-Threading (SMT), allowing each CPU core to handle multiple threads simultaneously. Disabling SMT can improve certain workloads or security, but may reduce multi-threaded performance.
- Enabled: Allows SMT to run and increases multi-threading performance.
- Disabled: Disables SMT to improve determinism or for specific workloads.
NUMA Nodes Per Socket (Default = 1):
This option defines the number of NUMA (Non-Uniform Memory Access) nodes per CPU socket. Adjusting this can impact memory access performance, especially in large-scale multi-socket systems.
- 1: Single NUMA node per socket.
- 2: Two NUMA nodes per socket, etc.
cTDP Control (Default = Auto):
This setting controls the configurable Thermal Design Power (cTDP) settings. Lowering cTDP can reduce power consumption, while increasing it can improve performance in power-limited environments.
- Auto: System will choose the optimal cTDP value.
- 35W, 45W, 65W, 95W: Different power options to balance performance and thermal output.
Memory Frequency (Default = Auto):
Configures the maximum memory frequency. If Enforce POR is disabled, user will be able to run at higher frequencies than the memory support (limited by processor support). Values for this BIOS option can be:
Determinism Slider (Default = Balanced):
This setting controls the balance between performance and deterministic behavior for workloads that require real-time performance. Adjust this to improve latency at the expense of throughput or vice versa.
- Balanced: Default setting for typical workloads.
- High Determinism: Reduces variance in latency at the expense of throughput.
- Low Determinism: Maximizes throughput but may introduce latency spikes.
First created Jan 21, 2025.
Last Updated Jan 2025.
For questions about the meanings of these flags, please contact the tester.
For other inquiries, please contact info@spec.org
Copyright 2017-2025 Standard Performance Evaluation Corporation
Tested with SPEC CPU2017 v1.1.9.
Report generated on 2025-01-28 22:09:00 by SPEC CPU2017 flags formatter v5178.
![[benchmark]](https://www.spec.org/auto/cpu2017/images/benchmark.png)