Re: [PATCH v2] futex: Use a keyed hash for global futex buckets

[kernel test robot <yi1.lai@intel.com>]

Hello,

kernel test robot noticed a -6.0% regression of will-it-scale.per_thread_ops on:


commit: c44a057178cbedbc04c63404258524975e87a64f ("[PATCH v2] futex: Use a keyed hash for global futex buckets")
url: https://github.com/intel-lab-lkp/linux/commits/Kyle-Zeng/futex-Use-a-keyed-hash-for-global-futex-buckets/20261019-113334
patch link: https://lore.kernel.org/all/20261019183334.29433-1-kylebot@openai.com/
patch subject: [PATCH v2] futex: Use a keyed hash for global futex buckets

testcase: will-it-scale
config: x86_64-rhel-9.4
compiler: gcc-14
test machine: 224 threads 2 sockets Intel(R) Xeon(R) Platinum 8480CTDX (Sapphire Rapids) with 512G memory
parameters:

  nr_task: 100%
  mode: thread
  test: futex2
  cpufreq_governor: performance


If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <yi1.lai@intel.com>
| Closes: https://lore.kernel.org/oe-lkp/202611050816.9e42490c-lkp@intel.com


Details are as below:
-------------------------------------------------------------------------------------------------->


The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20261105/202611050816.9e42490c-lkp@intel.com

=========================================================================================
compiler/cpufreq_governor/kconfig/mode/nr_task/rootfs/tbox_group/test/testcase:
  gcc-14/performance/x86_64-rhel-9.4/thread/100%/debian-13-x86_64-20250902.cgz/lkp-spr-2sp5/futex2/will-it-scale

commit: 
  0fcb05b723 ("Merge tag 'libcrypto-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux")
  c44a057178 ("[PATCH v2] futex: Use a keyed hash for global futex buckets")

0fcb05b72344f408 c44a057178cbedbc04c63404258
---------------- --------------------------- 
         %stddev     %change         %stddev
             \          |                \  
 7.026e+08            -6.0%  6.607e+08        will-it-scale.224.threads
   3136755            -6.0%    2949754        will-it-scale.per_thread_ops
 7.026e+08            -6.0%  6.607e+08        will-it-scale.workload


Disclaimer:
Results have been estimated based on internal Intel analysis and are provided
for informational purposes only. Any difference in system hardware or software
design or configuration may affect actual performance.


-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki