Greeting,

FYI, we noticed a -4.7% regression of stress-ng.vfork.ops_per_sec due to commit:

commit: 88294e6f6d1e1a9169cc9b715050bd8b52ac5f44 ("[PATCH v3 4/5] pid: mark pids associated with group leader tasks")
url: https://github.com/intel-lab-lkp/linux/commits/Brian-Foster/proc-improve-root-readdir-latency-with-many-threads/20221203-012018
base: https://git.kernel.org/cgit/linux/kernel/git/powerpc/linux.git next
patch link: https://lore.kernel.org/all/20221202171620.509140-5-bfoster@redhat.com/
patch subject: [PATCH v3 4/5] pid: mark pids associated with group leader tasks

in testcase: stress-ng
on test machine: 128 threads 2 sockets Intel(R) Xeon(R) Platinum 8358 CPU @ 2.60GHz (Ice Lake) with 128G memory
with following parameters:

	nr_threads: 100%
	testtime: 60s
	sc_pid_max: 4194304
	class: scheduler
	test: vfork
	cpufreq_governor: performance


Details are as below:

=========================================================================================
class/compiler/cpufreq_governor/kconfig/nr_threads/rootfs/sc_pid_max/tbox_group/test/testcase/testtime:
  scheduler/gcc-11/performance/x86_64-rhel-8.3/100%/debian-11.1-x86_64-20220510.cgz/4194304/lkp-icl-2sp5/vfork/stress-ng/60s

commit: 
  eae2900480 ("pid: switch pid_namespace from idr to xarray")
  88294e6f6d ("pid: mark pids associated with group leader tasks")

eae2900480d61b93 88294e6f6d1e1a9169cc9b71505 
---------------- --------------------------- 
         %stddev     %change         %stddev
             \          |                \  
  26176589 ±  3%      -5.4%   24757728        stress-ng.time.voluntary_context_switches
  11320148            -4.7%   10789611        stress-ng.vfork.ops
    188669            -4.7%     179826        stress-ng.vfork.ops_per_sec
     48483 ± 13%     +17.3%      56864 ±  3%  numa-vmstat.node1.nr_slab_unreclaimable
    721230 ±  4%      -5.7%     679849        vmstat.system.cs
   1192641 ±  3%     -21.4%     937830        sched_debug.cpu.curr->pid.max
    469229 ±  9%     -18.1%     384233 ±  5%  sched_debug.cpu.curr->pid.stddev
    768469 ±  4%      -6.0%     722315        perf-stat.i.context-switches
      0.09 ±  5%      -0.0        0.07 ±  3%  perf-stat.i.dTLB-load-miss-rate%
  10758930 ±  5%     -11.1%    9564450 ±  3%  perf-stat.i.dTLB-load-misses
   2480878 ±  2%      -4.1%    2380112 ±  2%  perf-stat.i.dTLB-store-misses
      0.15            +2.7%       0.15        perf-stat.i.ipc
  23566766            -3.5%   22751863        perf-stat.i.node-load-misses
  10701300            -4.6%   10206578        perf-stat.i.node-store-misses
      0.09 ±  4%      -0.0        0.08 ±  4%  perf-stat.overall.dTLB-load-miss-rate%
    743961 ±  4%      -6.0%     699259        perf-stat.ps.context-switches
  10436726 ±  5%     -11.3%    9261813 ±  4%  perf-stat.ps.dTLB-load-misses
  22838094            -3.4%   22057626        perf-stat.ps.node-load-misses
  10394494            -4.3%    9950784        perf-stat.ps.node-store-misses



If you fix the issue, kindly add following tag
| Reported-by: kernel test robot <yujie.liu@intel.com>
| Link: https://lore.kernel.org/oe-lkp/202212130906.15eab7ed-yujie.liu@intel.com


To reproduce:

        git clone https://github.com/intel/lkp-tests.git
        cd lkp-tests
        sudo bin/lkp install job.yaml           # job file is attached in this email
        bin/lkp split-job --compatible job.yaml # generate the yaml file for lkp run
        sudo bin/lkp run generated-yaml-file

        # if come across any failure that blocks the test,
        # please remove ~/.lkp and /lkp dir to run from a clean state.


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://01.org/lkp