linux-kernel - [tip:locking/futex] [futex] b04b8f3032: perf-bench-futex.ops/s 3.9% regression

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Message-ID: <202505191048.c1220460-lkp@intel.com>
Date: Mon, 19 May 2025 13:06:03 +0800
From: kernel test robot <oliver.sang@...el.com>
To: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
CC: <oe-lkp@...ts.linux.dev>, <lkp@...el.com>, <linux-kernel@...r.kernel.org>,
	<x86@...nel.org>, Peter Zijlstra <peterz@...radead.org>,
	<oliver.sang@...el.com>
Subject: [tip:locking/futex] [futex]  b04b8f3032:  perf-bench-futex.ops/s
 3.9% regression



Hello,

kernel test robot noticed a 3.9% regression of perf-bench-futex.ops/s on:


commit: b04b8f3032aae6121303bfa324c768faba032242 ("futex: Introduce futex_q_lockptr_lock()")
https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git locking/futex

[test failed on linux-next/master 484803582c77061b470ac64a634f25f89715be3f]

testcase: perf-bench-futex
config: x86_64-rhel-9.4
compiler: gcc-12
test machine: 192 threads 2 sockets Intel(R) Xeon(R) 6740E  CPU @ 2.4GHz (Sierra Forest) with 256G memory
parameters:

	runtime: 300s
	nr_task: 100%
	test: hash
	shared: shared
	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@...el.com>
| Closes: https://lore.kernel.org/oe-lkp/202505191048.c1220460-lkp@intel.com


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


The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20250519/202505191048.c1220460-lkp@intel.com

=========================================================================================
compiler/cpufreq_governor/kconfig/nr_task/rootfs/runtime/shared/tbox_group/test/testcase:
  gcc-12/performance/x86_64-rhel-9.4/100%/debian-12-x86_64-20240206.cgz/300s/shared/lkp-srf-2sp2/hash/perf-bench-futex

commit: 
  fe00e88d21 ("futex: Decrease the waiter count before the unlock operation")
  b04b8f3032 ("futex: Introduce futex_q_lockptr_lock()")

fe00e88d217a7bf7 b04b8f3032aae6121303bfa324c 
---------------- --------------------------- 
         %stddev     %change         %stddev
             \          |                \  
     17199 ±  8%      -9.4%      15577 ±  4%  numa-meminfo.node1.KernelStack
      4350 ± 14%     -16.1%       3649 ± 13%  numa-meminfo.node1.PageTables
     17199 ±  8%      -9.4%      15574 ±  4%  numa-vmstat.node1.nr_kernel_stack
      1088 ± 14%     -16.1%     913.51 ± 13%  numa-vmstat.node1.nr_page_table_pages
   2389657            -3.9%    2296088        perf-bench-futex.ops/s
      7000            -4.9%       6658        perf-bench-futex.time.user_time
    339.33 ± 19%     +45.8%     494.61 ± 19%  perf-sched.wait_and_delay.avg.ms.__cond_resched.smpboot_thread_fn.kthread.ret_from_fork.ret_from_fork_asm
      1991 ± 26%     +93.3%       3850 ±  6%  perf-sched.wait_and_delay.max.ms.__cond_resched.smpboot_thread_fn.kthread.ret_from_fork.ret_from_fork_asm
    339.33 ± 19%     +45.8%     494.60 ± 19%  perf-sched.wait_time.avg.ms.__cond_resched.smpboot_thread_fn.kthread.ret_from_fork.ret_from_fork_asm
      1991 ± 26%     +93.3%       3850 ±  6%  perf-sched.wait_time.max.ms.__cond_resched.smpboot_thread_fn.kthread.ret_from_fork.ret_from_fork_asm
      0.39            +1.7%       0.39        perf-stat.i.MPKI
 9.267e+10            -3.9%  8.904e+10        perf-stat.i.branch-instructions
 2.172e+08            -4.1%  2.082e+08        perf-stat.i.cache-misses
 5.278e+08            -3.7%  5.084e+08        perf-stat.i.cache-references
      1.09            +6.1%       1.15        perf-stat.i.cpi
      2814            +4.3%       2935        perf-stat.i.cycles-between-cache-misses
 5.631e+11            -5.8%  5.305e+11        perf-stat.i.instructions
      0.92            -5.8%       0.87        perf-stat.i.ipc
      0.39            +1.7%       0.39        perf-stat.overall.MPKI
      1.09            +6.1%       1.15        perf-stat.overall.cpi
      2815            +4.3%       2936        perf-stat.overall.cycles-between-cache-misses
      0.92            -5.8%       0.87        perf-stat.overall.ipc
 9.236e+10            -3.9%  8.875e+10        perf-stat.ps.branch-instructions
 2.165e+08            -4.1%  2.075e+08        perf-stat.ps.cache-misses
  5.26e+08            -3.7%  5.067e+08        perf-stat.ps.cache-references
 5.612e+11            -5.8%  5.288e+11        perf-stat.ps.instructions
 1.689e+14            -5.8%  1.592e+14        perf-stat.total.instructions




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