CPU2006 Flag Description
Sun Microsystems Sun Blade X6270 (Sun Studio no autopar, base only)

Compilers: Sun Studio 12 Update 1

Operating systems: OpenSolaris 2008.11

Last updated: 21-Apr-2009 jlh

The text for many of the descriptions below was taken from the Sun Studio Compiler Documentation, which is copyright © 2007-2009 Sun Microsystems, Inc. The original documentation can be found at docs.sun.com.

This document has both optimization flags (in the immediately following section) and a description of Platform Settings

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.

• • -D__MATHERR_ERRNO_DONTCARE
  • 
  • sun_cc,sun_CC

  • Allows the compiler to assume that your code does not rely on setting of the errno variable.

• • -fns
  • 

  • Selects faster (but nonstandard) handling of floating point arithmetic exceptions and gradual underflow. The spelling "-fns=yes" is equivalent to "-fns".

• • -fsimple=2
  • 

  • Controls simplifying assumptions for floating point arithmetic:

    • -fsimple=0 permits no simplifying assumptions. Preserves strict IEEE 754 conformance.
    • -fsimple=1 allows the optimizer to assume:
      • The IEEE 754 default rounding/trapping modes do not change after process initialization.
      • Computations producing no visible result other than potential floating-point exceptions may be deleted.
      • Computations with Infinity or NaNs as operands need not propagate NaNs to their results. For example, x*0 may be replaced by 0.
      • Computations do not depend on sign of zero.
    • -fsimple=2 permits more aggressive floating point optimizations that may cause programs to produce different numeric results due to changes in rounding. Even with -fsimple=2, the optimizer still is not permitted to introduce a floating point exception in a program that otherwise produces none. For example, -fsimple=2 permits the optimizer to replace computations of x/y in a loop with x*z, where z=1/y.
• • -fsingle
  • 
  • sun_cc

  • Evaluate float expressions as single precision.

• • -ftrap=%none
  • 

  • Turns off all IEEE 754 trapping modes.

• • -nofstore
  • 

  • Cancels forcing expressions to have the precision of the result.

• • -xalias_level=basic
  • 
  • sun_cc

  • Allows the compiler to perform type-based alias analysis at the specified alias level:

    • basic assume that memory references that involve different C basic types do not alias each other.
    • std assume aliasing rules described in the ISO 1999 C standard.
    • strong in addition to the restrictions at the std level, assume that pointers of type char * are used only to access an object of type char; and assume that there are no interior pointers.
    • strict assume that memory references that involve types such as structs or unions, that are the same when tags are removed, can alias each other. Conversely, the compiler assumes that memory references involving types that are not the same even after tags are removed do not alias each other.
• • -xbuiltin=%all
  • 
  • sun_cc,sun_CC

  • Substitute intrinsic functions or inline system functions where profitable for performance.

• • -xdepend
  • 

  • Analyze loops for inter-iteration data dependencies, and do loop restructuring.

• • -xlibmil
  • 

  • Use inline expansion for math library, libm.

• • -xlibmopt
  • 
  • sun_CC,sun_f90

  • Select the optimized math library.

• • -xO5
  • 

  • Specify optimization level. Can be written either as -xOn or -On, where n indicates:

    • O1 does only basic local optimizations (peephole.)
    • O2 Do basic local and global optimizations, such as induction variable elimination, common subexpression elimination, constant propogation, register allocation, and basic block merging.
    • O3 Add global optimizations at the function level, loop unrolling, and software pipelining. For Fortran, includes dependence analysis (-xdepend)
    • O4 Adds automatic inlining of functions in the same file.
    • O5 Uses optmization algorithms that may take significantly more compilation time or that do not have as high a probability of improving execution time, such as speculative code motion.
• • -xregs=no%frameptr
  • 

  • Allow the compiler to use the frame-pointer register (%ebp on IA32, %rbp on x64) as an unallocated callee-saves register.

• • -xtarget=native
  • 

  • Selects options appropriate for the system where the compile is taking place, including architecture, chip, and cache sizes. (These can also be controlled separately, via -xarch, -xchip, and -xcache, respectively.)

• • -dalign
  • 

  • Assume data is naturally aligned.

• • -ftrap_common
  • 

  • Sets the IEEE 754 trapping mode to common exceptions (invalid, division by zero, and overflow).

System and Other Tuning Information

Platform settings

One or more of the following settings may have been applied to the testbed. If so, the "Platform Notes" section of the report will say so; and you can read below to find out more about what these settings mean.

• Boot time, BIOS settings
• /etc/system
• Environment/shell Variables
• The Submit Command

Boot time, BIOS settings

Intel VT-d: Disabled
VT-d, if enabled, supports remapping of I/O DMA transfers for virtualization.

/etc/system settings

autoup=<n>
When the file system flush daemon fsflush runs, it writes to disk all modified file buffers that are more than n seconds old.

lpg_alloc_prefer=<n>
0 = the OS may allocate remote pages if the size requested is readily available in a remote locality group (default)
1 = Set lgroup page allocation to strongly prefer local pages.

tune_t_fsflushr=<n>
Controls the number of seconds between runs of the file system flush daemon, fsflush.

zfs:zfs_arc_max=<n>
Controls the amount of memory used by ZFS for caching of file system buffers.

Environment/shell variables

OMP_DYNAMIC=<TRUE|FALSE>
Enables (TRUE) or disables (FALSE) dynamic adjustment of the number of threads available for execution of parallel regions. The default is TRUE.

OMP_NESTED=<TRUE|FALSE>
Enables or disables nested parallelism. Value is either TRUE or FALSE. The default is FALSE.

OMP_NUM_THREADS=<n>
If programs have been compiled with -xautopar, this environment variable can be set to the number of processors that programs should use.

PARALLEL=<n>
If programs have been compiled with -xautopar, this environment variable can be set to the number of processors that programs should use.

STACKSIZE=<n>
Set the size of the stack (temporary storage area) for each slave thread of a multithreaded program.

SUNW_MP_PROCBIND=<n>
This environment variable can be used to bind the LWPs (lightweight processes) managed by the microtasking library, libmtsk, to processors. Performance can be enhanced with processor binding, but performance degradation will occur if multiple LWPs are bound to the same processor.
The value for SUNW_MP_PROCBIND can be:

• The string TRUE or FALSE (in any case).
• a non-negative integer.
• a list of two or more non-negative integers separated by one or more spaces (" ").
• two non-negative integers, n1 and n2, separated by a minus ("-"); n1 must be less than or equal to n2.

Integers in the above denote the "logical" processor IDs to which the LWPs are to be bound. Logical processor IDs are consecutive integers that start with 0, and may or may not be identical to the actual processsor IDs. If n processors are available online, then their logical processor IDs are 0, 1, ..., n-1.
By default, LWPs are not bound to processors. It is left up to the operating system, Solaris, to schedule LWPs onto processors.
If the value "TRUE" is used, the operating system will bind processes to processors, starting with processor 0.

SUNW_MP_THR_IDLE=SPIN
Controls the end-of-task status of each helper thread executing the parallel part of a program. You can set the value to spin, sleep ns, or sleep nms. The default is SPIN -- the thread spins (or busy-waits) after completing a parallel task until a new parallel task arrives.

ulimit -s <n>
Sets the stack size to n kbytes, or "unlimited" to allow the stack size to grow without limit.

The Submit Command

submit=echo 'pbind -b...' > dobmk; sh dobmk
When running multiple copies of benchmarks, the SPEC config file feature submit is sometimes used to cause individual jobs to be bound to specific processors. If so, the specific command may be found in the config file; here is a brief guide to understanding that command:

• submit= causes the SPEC tools to use this line when submitting jobs.
• echo ...> dobmk causes the generated commands to be written to a file, namely dobmk.
• pbind -b causes this copy's processes to be bound to the CPU specified by the expression that follows it. See the config file used in the submission for the exact syntax, which tends to be cumbersome because of the need to carefully quote parts of the expression. When all expressions are evaluated, each core ends up with exactly one copy of each benchmark. The pbind expression may include:
  • $SPECCOPYNUM: the SPEC tools-assigned number for this copy of the benchmark.
  • psrinfo: find out what processors are available
  • grep on-line: search the psrinfo output for information regarding on-line cpus
  • expr: Calculate simple arithmetic expressions. For example, the effect of binding jobs to a (quote-resolved) expression such as:
    expr ( $SPECCOPYNUM / 4 ) * 8 + ($SPECCOPYNUM % 4 ) )
    would be to send the jobs to processors whose numbers are:
    0,1,2,3, 8,9,10,11, 16,17,18,19 ...
  • awk...print \$1: Pick out the line corresponding to this copy of the benchmark and use the CPU number mentioned at the start of this line.
• sh dobmk actually runs the benchmark.

Flag description origin markings:

	Indicates that the flag description came from the user flags file.
	Indicates that the flag description came from the suite-wide flags file.
	Indicates that the flag description came from a per-benchmark flags file.

For questions about the meanings of these flags, please contact the tester.
For other inquiries, please contact webmaster@spec.org
Copyright 2006-2014 Standard Performance Evaluation Corporation
Tested with SPEC CPU2006 v1.1.
Report generated on Wed Jul 23 01:34:35 2014 by SPEC CPU2006 flags formatter v6906.