membw: Fix compilation error when avx512 is not supported by gcc

xiaochenshen commented 4 years ago

The membw tool depends on AVX-512 foundation instructions, which are supported in gcc version 4.9 or above. Building with older version gcc leads to compilation failure.

Add CFLAGs -mavx512f in Makefile only when gcc supports avx512. In addition, add gcc version check in avx512 related stores operations.

Signed-off-by: Xiaochen Shen xiaochen.shen@intel.com

Description

Fix https://github.com/intel/intel-cmt-cat/issues/156

NOTE:

Please don't merge the dependent commit https://github.com/intel/intel-cmt-cat/pull/157/commits/530969574cd68e4ae2dd4a89c02f6857b1c71326 which is addressed in https://github.com/intel/intel-cmt-cat/pull/155
I will rebase the code when https://github.com/intel/intel-cmt-cat/pull/155 is merged.

Affected parts

[ ] library
[ ] pqos utility
[ ] rdtset utility
[x] other: (please specify) membw

Motivation and Context

Fix https://github.com/intel/intel-cmt-cat/issues/156 This issue breaks the building of intel-cmt-cat if avx512 is not supported by gcc.

How Has This Been Tested?

Test steps:

Without the fix:

# make
…
cc: error: unrecognized command line option ‘-mavx512f’
make[1]: *** [membw.o] Error 1
make[1]: Leaving directory `/home/xiaochen/intel-cmt-cat/tools/membw'
make: *** [all] Error 2

With the fix:

Case 1: CPU doesn't support AVX-512 (Broadwell server, gcc 4.8.5):

# ./membw -c 0 -b 50000 --write-avx512
No CPU support for AVX512 instructions!

# ./membw -c 0 -b 50000 --nt-write-avx512
No CPU support for AVX512 instructions!

Case 2: CPU supports AVX-512 but gcc doesn't support AVX-512 (Skylake server, gcc 4.8.5):

# ./membw -c 0 -b 50000 --write-avx512
- THREAD logical core id: 0,  memory bandwidth [MB]: 50000, starting...
No GCC support for AVX512 instructions!

exiting…

# ./membw -c 0 -b 50000 --nt-write-avx512
- THREAD logical core id: 0,  memory bandwidth [MB]: 50000, starting...
No GCC support for AVX512 instructions!

exiting...

Case 3: Both CPU and gcc support AVX-512 (Ice Lake server, gcc 8.3.1):
# ./membw -c 0 -b 50000 --write-avx512
- THREAD logical core id: 0,  memory bandwidth [MB]: 50000, starting...

# ./membw -c 0 -b 50000 --nt-write-avx512
- THREAD logical core id: 0,  memory bandwidth [MB]: 50000, starting...

Types of changes

[x] Bug fix (non-breaking change which fixes an issue)
[ ] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

[x] My code follows the code style of this project.
[ ] My change requires a change to the documentation.
[ ] I have updated the documentation accordingly.

xiaochenshen commented 4 years ago

I have rebased this PR against master branch for https://github.com/intel/intel-cmt-cat/pull/155 is merged.

xiaochenshen commented 4 years ago

Closed for this PR has been merged.

intel / intel-cmt-cat