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Message-ID: <202506121540.6eafcec4-lkp@intel.com>
Date: Thu, 12 Jun 2025 15:17:35 +0800
From: kernel test robot <oliver.sang@...el.com>
To: Colin Ian King <colin.i.king@...il.com>
CC: <oe-lkp@...ts.linux.dev>, <lkp@...el.com>, <linux-kernel@...r.kernel.org>,
	Christian Brauner <brauner@...nel.org>, <linux-fsdevel@...r.kernel.org>,
	<oliver.sang@...el.com>
Subject: [linus:master] [select]  5730609ffd:  will-it-scale.per_process_ops
 3.9% improvement



Hello,

kernel test robot noticed a 3.9% improvement of will-it-scale.per_process_ops on:


commit: 5730609ffd7e558e1e3305d0c6839044e8f6591b ("select: do_pollfd: add unlikely branch hint return path")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master


testcase: will-it-scale
config: x86_64-rhel-9.4
compiler: gcc-12
test machine: 104 threads 2 sockets (Skylake) with 192G memory
parameters:

	nr_task: 100%
	mode: process
	test: poll2
	cpufreq_governor: performance



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


The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20250612/202506121540.6eafcec4-lkp@intel.com

=========================================================================================
compiler/cpufreq_governor/kconfig/mode/nr_task/rootfs/tbox_group/test/testcase:
  gcc-12/performance/x86_64-rhel-9.4/process/100%/debian-12-x86_64-20240206.cgz/lkp-skl-fpga01/poll2/will-it-scale

commit: 
  f1745496d3 ("netfs: Update main API document")
  5730609ffd ("select: do_pollfd: add unlikely branch hint return path")

f1745496d3fba34a 5730609ffd7e558e1e3305d0c68 
---------------- --------------------------- 
         %stddev     %change         %stddev
             \          |                \  
      0.08 ± 31%     -35.8%       0.05 ± 31%  perf-sched.sch_delay.avg.ms.schedule_timeout.__wait_for_common.wait_for_completion_state.kernel_clone
      2800 ± 91%    +420.5%      14576 ±121%  proc-vmstat.numa_hint_faults
      1013 ± 37%    +226.4%       3308 ±101%  proc-vmstat.numa_hint_faults_local
  25518332            +3.9%   26506874        will-it-scale.104.processes
    245368            +3.9%     254873        will-it-scale.per_process_ops
  25518332            +3.9%   26506874        will-it-scale.workload
 4.802e+10            +3.8%  4.983e+10        perf-stat.i.branch-instructions
 1.475e+08            +3.4%  1.525e+08        perf-stat.i.branch-misses
      1.04            -3.6%       1.00        perf-stat.i.cpi
 2.702e+11            +3.9%  2.808e+11        perf-stat.i.instructions
      0.97            +3.7%       1.00        perf-stat.i.ipc
      1.03            -3.6%       1.00        perf-stat.overall.cpi
      0.97            +3.7%       1.00        perf-stat.overall.ipc
 4.786e+10            +3.8%  4.966e+10        perf-stat.ps.branch-instructions
  1.47e+08            +3.4%   1.52e+08        perf-stat.ps.branch-misses
 2.693e+11            +3.9%  2.799e+11        perf-stat.ps.instructions
  8.15e+13            +3.9%  8.468e+13        perf-stat.total.instructions
     42.32            -4.1       38.22        perf-profile.calltrace.cycles-pp.fdget.do_poll.do_sys_poll.__x64_sys_poll.do_syscall_64
     69.75            -2.1       67.63        perf-profile.calltrace.cycles-pp.do_sys_poll.__x64_sys_poll.do_syscall_64.entry_SYSCALL_64_after_hwframe.__poll
     70.28            -2.1       68.17        perf-profile.calltrace.cycles-pp.__x64_sys_poll.do_syscall_64.entry_SYSCALL_64_after_hwframe.__poll
     72.20            -2.0       70.23        perf-profile.calltrace.cycles-pp.do_syscall_64.entry_SYSCALL_64_after_hwframe.__poll
     76.46            -1.8       74.67        perf-profile.calltrace.cycles-pp.entry_SYSCALL_64_after_hwframe.__poll
     58.10            -1.5       56.63        perf-profile.calltrace.cycles-pp.do_poll.do_sys_poll.__x64_sys_poll.do_syscall_64.entry_SYSCALL_64_after_hwframe
     94.49            -0.5       93.97        perf-profile.calltrace.cycles-pp.__poll
      0.70            +0.0        0.72        perf-profile.calltrace.cycles-pp.__virt_addr_valid.check_heap_object.__check_object_size.do_sys_poll.__x64_sys_poll
      0.92            +0.0        0.95        perf-profile.calltrace.cycles-pp.check_heap_object.__check_object_size.do_sys_poll.__x64_sys_poll.do_syscall_64
      0.54            +0.0        0.58 ±  2%  perf-profile.calltrace.cycles-pp.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.__poll
      1.94            +0.1        2.00        perf-profile.calltrace.cycles-pp.__check_object_size.do_sys_poll.__x64_sys_poll.do_syscall_64.entry_SYSCALL_64_after_hwframe
      1.68            +0.1        1.74        perf-profile.calltrace.cycles-pp.rep_movs_alternative._copy_from_user.do_sys_poll.__x64_sys_poll.do_syscall_64
      2.34            +0.1        2.40        perf-profile.calltrace.cycles-pp._copy_from_user.do_sys_poll.__x64_sys_poll.do_syscall_64.entry_SYSCALL_64_after_hwframe
      0.89            +0.1        0.96        perf-profile.calltrace.cycles-pp.kfree.do_sys_poll.__x64_sys_poll.do_syscall_64.entry_SYSCALL_64_after_hwframe
      2.85            +0.1        2.98        perf-profile.calltrace.cycles-pp.entry_SYSCALL_64.__poll
      5.86            +0.3        6.16        perf-profile.calltrace.cycles-pp.entry_SYSRETQ_unsafe_stack.__poll
      7.26            +0.5        7.72        perf-profile.calltrace.cycles-pp.syscall_return_via_sysret.__poll
      5.00 ±  2%      +0.5        5.51 ±  2%  perf-profile.calltrace.cycles-pp.testcase
      2.27 ±  3%      +0.6        2.84 ±  4%  perf-profile.calltrace.cycles-pp.entry_SYSCALL_64_safe_stack.__poll
     42.25            -2.8       39.42        perf-profile.children.cycles-pp.fdget
     58.21            -2.7       55.52        perf-profile.children.cycles-pp.do_poll
     70.35            -2.1       68.24        perf-profile.children.cycles-pp.__x64_sys_poll
     69.87            -2.1       67.77        perf-profile.children.cycles-pp.do_sys_poll
     72.26            -2.0       70.29        perf-profile.children.cycles-pp.do_syscall_64
     76.58            -1.8       74.80        perf-profile.children.cycles-pp.entry_SYSCALL_64_after_hwframe
     95.09            -0.5       94.58        perf-profile.children.cycles-pp.__poll
      0.71            +0.0        0.73        perf-profile.children.cycles-pp.__virt_addr_valid
      0.99            +0.0        1.02        perf-profile.children.cycles-pp.check_heap_object
      0.19 ±  2%      +0.0        0.22 ±  3%  perf-profile.children.cycles-pp.poll_freewait
      0.54            +0.0        0.59 ±  2%  perf-profile.children.cycles-pp.syscall_exit_to_user_mode
      1.70            +0.1        1.76        perf-profile.children.cycles-pp.rep_movs_alternative
      2.09            +0.1        2.14        perf-profile.children.cycles-pp.__check_object_size
      0.89            +0.1        0.96        perf-profile.children.cycles-pp.kfree
      2.56            +0.1        2.64        perf-profile.children.cycles-pp._copy_from_user
      6.28            +0.3        6.60        perf-profile.children.cycles-pp.entry_SYSRETQ_unsafe_stack
      1.30 ±  2%      +0.3        1.61 ±  2%  perf-profile.children.cycles-pp.entry_SYSCALL_64_safe_stack
      3.84            +0.4        4.22        perf-profile.children.cycles-pp.entry_SYSCALL_64
      7.33            +0.5        7.79        perf-profile.children.cycles-pp.syscall_return_via_sysret
      5.01 ±  2%      +0.5        5.52 ±  2%  perf-profile.children.cycles-pp.testcase
     40.83            -1.6       39.20        perf-profile.self.cycles-pp.fdget
     17.11            -1.0       16.07        perf-profile.self.cycles-pp.do_poll
      0.16 ±  3%      +0.0        0.18 ±  3%  perf-profile.self.cycles-pp.poll_freewait
      0.65            +0.0        0.68        perf-profile.self.cycles-pp.__virt_addr_valid
      0.98            +0.0        1.01        perf-profile.self.cycles-pp._copy_from_user
      0.42 ±  2%      +0.0        0.46 ±  2%  perf-profile.self.cycles-pp.syscall_exit_to_user_mode
      1.54            +0.0        1.58        perf-profile.self.cycles-pp.rep_movs_alternative
      1.08            +0.1        1.14 ±  2%  perf-profile.self.cycles-pp.__poll
      0.88            +0.1        0.95        perf-profile.self.cycles-pp.kfree
      4.39 ±  2%      +0.2        4.59 ±  2%  perf-profile.self.cycles-pp.entry_SYSCALL_64_after_hwframe
      6.22            +0.3        6.53        perf-profile.self.cycles-pp.entry_SYSRETQ_unsafe_stack
      3.41            +0.4        3.78        perf-profile.self.cycles-pp.entry_SYSCALL_64
      7.32            +0.5        7.78        perf-profile.self.cycles-pp.syscall_return_via_sysret
      4.82 ±  2%      +0.5        5.32 ±  2%  perf-profile.self.cycles-pp.testcase




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


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