[linus:master] [fs] 7eb84d54fa: stress-ng.kvm.ops_per_sec 28.2% regression

[linus:master] [fs] 7eb84d54fa: stress-ng.kvm.ops_per_sec 28.2% regression

[kernel test robot]

Hello,

kernel test robot noticed a 28.2% regression of stress-ng.kvm.ops_per_sec on:


commit: 7eb84d54fac5002bd975d1de8fd61d57e89172ab ("fs: don't let a migrating task hide its reference from do_umount()") https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master

testcase: stress-ng
config: x86_64-rhel-9.4
compiler: gcc-14
test machine: 192 threads 2 sockets Intel(R) Xeon(R) 6740E  CPU @ 2.4GHz (Sierra Forest) with 256G memory
parameters:

	nr_threads: 100%
	testtime: 60s
	test: kvm
	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/202610130959.d3ca4cfa-lkp@intel.com


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


The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20261013/202610130959.d3ca4cfa-lkp@intel.com

=========================================================================================
compiler/cpufreq_governor/kconfig/nr_threads/rootfs/tbox_group/test/testcase/testtime:
  gcc-14/performance/x86_64-rhel-9.4/100%/debian-13-x86_64-20250902.cgz/lkp-srf-2sp2/kvm/stress-ng/60s

commit: 
  bba9960c07 ("selftests/filesystems: check that a busy propagated copy blocks a synchronous umount")
  7eb84d54fa ("fs: don't let a migrating task hide its reference from do_umount()")

bba9960c073dbea8 7eb84d54fac5002bd975d1de8fd
---------------- --------------------------- 
         %stddev     %change         %stddev
             \          |                \  
    134749           -28.2%      96786 ±  2%  stress-ng.kvm.ops
      2245           -28.2%       1612 ±  2%  stress-ng.kvm.ops_per_sec
    571737           -25.3%     427284 ±  3%  stress-ng.time.minor_page_faults
      7905 ±  3%     +35.2%      10690 ±  6%  stress-ng.time.percent_of_cpu_this_job_got
      4566 ±  3%     +37.9%       6297 ±  6%  stress-ng.time.system_time
    190.93           -28.1%     137.21 ±  2%  stress-ng.time.user_time
    698896           -24.8%     525918        stress-ng.time.voluntary_context_switches


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