[linus:master] [nfsd] eccbbc7c00: dbench.max_latency 99.9% improvement

[linus:master] [nfsd] eccbbc7c00: dbench.max_latency 99.9% improvement

[kernel test robot]

Hello,

kernel test robot noticed a 99.9% improvement of dbench.max_latency on:


commit: eccbbc7c00a5aae5e704d4002adfaf4c3fa4b30d ("nfsd: don't use sv_nrthreads in connection limiting calculations.")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master


testcase: dbench
config: x86_64-rhel-9.4
compiler: gcc-12
test machine: 224 threads 4 sockets Intel(R) Xeon(R) Platinum 8380H CPU @ 2.90GHz (Cooper Lake) with 192G memory
parameters:

	nr_threads: 100%
	cpufreq_governor: performance
	disk: 1HDD
	fs: btrfs
	fs2: nfs



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


The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20250421/202504211304.eb2ca0c2-lkp@intel.com

=========================================================================================
compiler/cpufreq_governor/disk/fs2/fs/kconfig/nr_threads/rootfs/tbox_group/testcase:
  gcc-12/performance/1HDD/nfs/btrfs/x86_64-rhel-9.4/100%/debian-12-x86_64-20240206.cgz/lkp-cpl-4sp2/dbench

commit: 
  de71d4e211 ("nfsd: fix legacy client tracking initialization")
  eccbbc7c00 ("nfsd: don't use sv_nrthreads in connection limiting calculations.")

de71d4e211eddb67 eccbbc7c00a5aae5e704d4002ad 
---------------- --------------------------- 
       fail:runs  %reproduction    fail:runs
           |             |             |    
         10:10        -100%            :10    stderr.has_stderr
         10:10        -100%            :10    stderr.nfsproc3_create_3_failed_in_nfsio_create
         %stddev     %change         %stddev
             \          |                \  
     71006           -99.9%      35.66 ±  7%  dbench.max_latency
     71006           -99.9%      35.66 ±  7%  dbench.max_latency_harmonic_mean
      1.11            +0.1        1.16        perf-stat.i.branch-miss-rate%
  80903221            +6.3%   86014278 ±  2%  perf-stat.i.branch-misses
      1.10            +0.1        1.16        perf-stat.overall.branch-miss-rate%
  79601951            +6.3%   84615085 ±  2%  perf-stat.ps.branch-misses




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