SPEC CPU2006 Platform Settings for Windows-based systems

System and Other Tuning Information

Platform settings

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

KMP_STACKSIZE

Specify stack size to be allocated for each thread.

KMP_AFFINITY

KMP_AFFINITY = < physical | logical >, starting-core-id
specifies the static mapping of user threads to physical cores. For example, if you have a system configured with 8 cores, OMP_NUM_THREADS=8 and KMP_AFFINITY=physical,0 then thread 0 will mapped to core 0, thread 1 will be mapped to core 1, and so on in a round-robin fashion.

KMP_AFFINITY = granularity=fine,scatter
The value for the environment variable KMP_AFFINITY affects how the threads from an auto-parallelized program are scheduled across processors.
Specifying granularity=fine selects the finest granularity level, causes each OpenMP thread to be bound to a single thread context.
This ensures that there is only one thread per core on cores supporting HyperThreading Technology
Specifying scatter distributes the threads as evenly as possible across the entire system.
Hence a combination of these two options, will spread the threads evenly across sockets, with one thread per physical core.

OMP_NUM_THREADS

Sets the maximum number of threads to use for OpenMP* parallel regions if no other value is specified in the application. This environment variable applies to both -openmp and -parallel (Linux and Mac OS X) or /Qopenmp and /Qparallel (Windows). Example syntax on a Linux system with 8 cores: export OMP_NUM_THREADS=8

Hardware Prefetch:

This BIOS option allows the enabling/disabling of a processor mechanism to prefetch data into the cache according to a pattern-recognition algorithm.

In some cases, setting this option to Disabled may improve performance. Users should only disable this option after performing application benchmarking to verify improved performance in their environment.

Adjacent Sector Prefetch:

This BIOS option allows the enabling/disabling of a processor mechanism to fetch the adjacent cache line within an 128-byte sector that contains the data needed due to a cache line miss.

submit= specperl -e "system sprintf qq{start /b /wait /affinity %x %s}, (1<<$SPECCOPYNUM), qq{ $command } "

When running multiple copies of benchmarks, the SPEC config file feature submit is used to cause individual jobs to be bound to specific processors. This specific submit command is used for Windows. The description of the elements of the command are:

start /b /wait /affinity mask command :
The start command is used to launch a new COMMAND with a given CPU affinity. The CPU affinity is represented as a bitmask, with the lowest order bit corresponding to the first logical CPU and highest order bit corresponding to the last logical CPU. The process is only allowed to run on a particular logical processor when the corresponding bit in the mask has been set to 1.
mask: The bitmask (in hexadecimal) corresponding to a specific SPECCOPYNUM. For example, the mask value for the first copy of a rate run will be 0x00000001, for the second copy of the rate will be 0x00000010 etc. Thus, the first copy of the rate run will have a CPU affinity of CPU0, the second copy will have the affinity CPU1 etc.
command: Program to be started, in this case, the benchmark instance to be started.