[linus:master] [mm] f822a9a81a: stress-ng.bigheap.realloc_calls_per_sec 37.3% regression

[kernel test robot <oliver.sang@intel.com>]

Hello,

kernel test robot noticed a 37.3% regression of stress-ng.bigheap.realloc_calls_per_sec on:


commit: f822a9a81a31311d67f260aea96005540b18ab07 ("mm: optimize mremap() by PTE batching")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master

[still regression on      linus/master 186f3edfdd41f2ae87fc40a9ccba52a3bf930994]
[still regression on linux-next/master b9ddaa95fd283bce7041550ddbbe7e764c477110]

testcase: stress-ng
config: x86_64-rhel-9.4
compiler: gcc-12
test machine: 192 threads 2 sockets Intel(R) Xeon(R) Platinum 8468V  CPU @ 2.4GHz (Sapphire Rapids) with 384G memory
parameters:

	nr_threads: 100%
	testtime: 60s
	test: bigheap
	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 <oliver.sang@intel.com>
| Closes: https://lore.kernel.org/oe-lkp/202508071609.4e743d7c-lkp@intel.com


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


The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20250807/202508071609.4e743d7c-lkp@intel.com

=========================================================================================
compiler/cpufreq_governor/kconfig/nr_threads/rootfs/tbox_group/test/testcase/testtime:
  gcc-12/performance/x86_64-rhel-9.4/100%/debian-12-x86_64-20240206.cgz/igk-spr-2sp1/bigheap/stress-ng/60s

commit: 
  94dab12d86 ("mm: call pointers to ptes as ptep")
  f822a9a81a ("mm: optimize mremap() by PTE batching")

94dab12d86cf77ff f822a9a81a31311d67f260aea96 
---------------- --------------------------- 
         %stddev     %change         %stddev
             \          |                \  
     13777 ± 37%     +45.0%      19979 ± 27%  numa-vmstat.node1.nr_slab_reclaimable
    367205            +2.3%     375703        vmstat.system.in
     55106 ± 37%     +45.1%      79971 ± 27%  numa-meminfo.node1.KReclaimable
     55106 ± 37%     +45.1%      79971 ± 27%  numa-meminfo.node1.SReclaimable
    559381           -37.3%     350757        stress-ng.bigheap.realloc_calls_per_sec
     11468            +1.2%      11603        stress-ng.time.system_time
    296.25            +4.5%     309.70        stress-ng.time.user_time
      0.81 ±187%    -100.0%       0.00        perf-sched.sch_delay.avg.ms.__cond_resched.zap_pte_range.zap_pmd_range.isra.0
      9.36 ±165%    -100.0%       0.00        perf-sched.sch_delay.max.ms.__cond_resched.zap_pte_range.zap_pmd_range.isra.0
      0.81 ±187%    -100.0%       0.00        perf-sched.wait_time.avg.ms.__cond_resched.zap_pte_range.zap_pmd_range.isra.0
      9.36 ±165%    -100.0%       0.00        perf-sched.wait_time.max.ms.__cond_resched.zap_pte_range.zap_pmd_range.isra.0
      5.50 ± 17%    +390.9%      27.00 ± 56%  perf-c2c.DRAM.local
    388.50 ± 10%    +114.7%     834.17 ± 33%  perf-c2c.DRAM.remote
      1214 ± 13%    +107.3%       2517 ± 31%  perf-c2c.HITM.local
    135.00 ± 19%    +130.9%     311.67 ± 32%  perf-c2c.HITM.remote
      1349 ± 13%    +109.6%       2829 ± 31%  perf-c2c.HITM.total




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