Re: [linux-next:master] [fs] 2e4c6e78f4: will-it-scale.per_thread_ops -5.7% regression

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On Wed, 2024-10-09 at 10:53 +0800, kernel test robot wrote:
> hi, Jeff Layton,
> 
> we reported
> "[brauner-vfs:vfs.mgtime] [fs]  a037d5e7f8: will-it-scale.per_thread_ops -5.5% regression"
> for this commit about one month ago.
> 
> we also saw you sent out patch for it.
> 
> now we noticed the commit is merged into linux-next/master now. besides
> will-it-scale, we also captured a hackbench regression. so we report this again
> FYI what we observed in our tests. thanks
> 
> 
> 
> Hello,
> 
> kernel test robot noticed a -5.7% regression of will-it-scale.per_thread_ops on:
> 

This is consistent with the results I was getting in my own testing.
The multigrain series does cause a small performance hit in this sort
of microbenchmark as fetching the floor and manipulating it has a cost.
I don't think there is much we can do to mitigate that unfortunately.

> 
> commit: 2e4c6e78f41afefb7a2b825b7aa4d90070720992 ("fs: add infrastructure for multigrain timestamps")
> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
> 
> testcase: will-it-scale
> test machine: 224 threads 4 sockets Intel(R) Xeon(R) Platinum 8380H CPU @ 2.90GHz (Cooper Lake) with 192G memory
> parameters:
> 
> 	nr_task: 100%
> 	mode: thread
> 	test: pipe1
> 	cpufreq_governor: performance
> 
> 
> In addition to that, the commit also has significant impact on the following tests:
> 
> +------------------+--------------------------------------------------------------------------------------------+
> > testcase: change | hackbench: hackbench.throughput -4.5% regression                                           |
> > test machine     | 128 threads 2 sockets Intel(R) Xeon(R) Gold 6338 CPU @ 2.00GHz (Ice Lake) with 256G memory |
> > test parameters  | cpufreq_governor=performance                                                               |
> >                  | ipc=pipe                                                                                   |
> >                  | iterations=4                                                                               |
> >                  | mode=threads                                                                               |
> >                  | nr_threads=800%                                                                            |
> +------------------+--------------------------------------------------------------------------------------------+
> > testcase: change | will-it-scale: will-it-scale.per_process_ops -2.0% regression                              |
> > test machine     | 104 threads 2 sockets (Skylake) with 192G memory                                           |
> > test parameters  | cpufreq_governor=performance                                                               |
> >                  | mode=process                                                                               |
> >                  | nr_task=100%                                                                               |
> >                  | test=pipe1                                                                                 |
> +------------------+--------------------------------------------------------------------------------------------+
> 
> 
> 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@xxxxxxxxx>
> > Closes: https://lore.kernel.org/oe-lkp/202410091041.6f5d221e-oliver.sang@xxxxxxxxx
> 
> 
> Details are as below:
> -------------------------------------------------------------------------------------------------->
> 
> 
> The kernel config and materials to reproduce are available at:
> https://download.01.org/0day-ci/archive/20241009/202410091041.6f5d221e-oliver.sang@xxxxxxxxx
> 
> =========================================================================================
> compiler/cpufreq_governor/kconfig/mode/nr_task/rootfs/tbox_group/test/testcase:
>   gcc-12/performance/x86_64-rhel-8.3/thread/100%/debian-12-x86_64-20240206.cgz/lkp-cpl-4sp2/pipe1/will-it-scale
> 
> commit: 
>   v6.12-rc1
>   2e4c6e78f4 ("fs: add infrastructure for multigrain timestamps")
> 
>        v6.12-rc1 2e4c6e78f41afefb7a2b825b7aa 
> ---------------- --------------------------- 
>          %stddev     %change         %stddev
>              \          |                \  
>     806865 ± 12%    +127.6%    1836795 ± 68%  numa-meminfo.node3.FilePages
>      32494 ±  7%     +39.2%      45235 ± 25%  numa-meminfo.node3.Mapped
>     201722 ± 12%    +127.7%     459227 ± 68%  numa-vmstat.node3.nr_file_pages
>       8032 ±  7%     +38.6%      11136 ± 26%  numa-vmstat.node3.nr_mapped
>    2657388 ± 13%     -28.2%    1907049 ± 11%  sched_debug.cfs_rq:/.avg_vruntime.stddev
>    2657388 ± 13%     -28.2%    1907049 ± 11%  sched_debug.cfs_rq:/.min_vruntime.stddev
>  2.921e+08            -5.7%  2.754e+08        will-it-scale.224.threads
>    1303879            -5.7%    1229301        will-it-scale.per_thread_ops
>  2.921e+08            -5.7%  2.754e+08        will-it-scale.workload
>     210109            +1.5%     213268        proc-vmstat.nr_active_anon
>     222111            +1.5%     225492        proc-vmstat.nr_shmem
>     210109            +1.5%     213268        proc-vmstat.nr_zone_active_anon
>     164529            +1.6%     167080        proc-vmstat.pgactivate
>       1.52 ± 82%     -78.7%       0.32 ± 18%  perf-sched.sch_delay.max.ms.irqentry_exit_to_user_mode.asm_sysvec_call_function_single.[unknown].[unknown]
>       3.03 ± 82%     -78.7%       0.65 ± 18%  perf-sched.wait_and_delay.max.ms.irqentry_exit_to_user_mode.asm_sysvec_call_function_single.[unknown].[unknown]
>      28.66 ± 95%     -75.5%       7.01 ±  5%  perf-sched.wait_and_delay.max.ms.schedule_timeout.__wait_for_common.wait_for_completion_state.kernel_clone
>       1.52 ± 82%     -78.7%       0.32 ± 18%  perf-sched.wait_time.max.ms.irqentry_exit_to_user_mode.asm_sysvec_call_function_single.[unknown].[unknown]
>      27.97 ± 98%     -76.0%       6.72 ±  5%  perf-sched.wait_time.max.ms.schedule_timeout.__wait_for_common.wait_for_completion_state.kernel_clone
>  1.971e+08 ±  4%     +13.2%  2.231e+08 ±  2%  perf-stat.i.branch-misses
>       1.11            -2.3%       1.09        perf-stat.i.cpi
>  6.697e+11            +2.2%  6.842e+11        perf-stat.i.instructions
>       0.90            +2.3%       0.92        perf-stat.i.ipc
>       0.00 ±141%    +162.1%       0.01 ± 38%  perf-stat.i.major-faults
>       0.12 ±  4%      +0.0        0.14 ±  2%  perf-stat.overall.branch-miss-rate%
>       1.11            -2.2%       1.09        perf-stat.overall.cpi
>       0.90            +2.3%       0.92        perf-stat.overall.ipc
>     695559            +8.3%     753229        perf-stat.overall.path-length
>  1.964e+08 ±  4%     +13.2%  2.223e+08 ±  2%  perf-stat.ps.branch-misses
>  6.676e+11            +2.2%   6.82e+11        perf-stat.ps.instructions
>       0.00 ±141%    +167.2%       0.01 ± 41%  perf-stat.ps.major-faults
>  2.032e+14            +2.1%  2.074e+14        perf-stat.total.instructions
>       7.01            -0.4        6.62        perf-profile.calltrace.cycles-pp.clear_bhb_loop.write
>       7.02            -0.4        6.66        perf-profile.calltrace.cycles-pp.clear_bhb_loop.read
>       5.52            -0.4        5.17        perf-profile.calltrace.cycles-pp.copy_page_from_iter.pipe_write.vfs_write.ksys_write.do_syscall_64
>       5.47            -0.3        5.15        perf-profile.calltrace.cycles-pp.entry_SYSCALL_64.read
>       5.47            -0.3        5.16        perf-profile.calltrace.cycles-pp.entry_SYSCALL_64.write
>       4.27            -0.2        4.02        perf-profile.calltrace.cycles-pp.copy_page_to_iter.pipe_read.vfs_read.ksys_read.do_syscall_64
>       3.87            -0.2        3.64 ±  2%  perf-profile.calltrace.cycles-pp._copy_from_iter.copy_page_from_iter.pipe_write.vfs_write.ksys_write
>       3.16            -0.2        3.00        perf-profile.calltrace.cycles-pp._copy_to_iter.copy_page_to_iter.pipe_read.vfs_read.ksys_read
>      53.32            -0.1       53.18        perf-profile.calltrace.cycles-pp.write
>       2.12            -0.1        1.98        perf-profile.calltrace.cycles-pp.__wake_up_sync_key.pipe_write.vfs_write.ksys_write.do_syscall_64
>       1.59            -0.1        1.48        perf-profile.calltrace.cycles-pp._raw_spin_lock_irqsave.__wake_up_sync_key.pipe_write.vfs_write.ksys_write
>       1.12            -0.1        1.03        perf-profile.calltrace.cycles-pp.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.read
>       0.97            -0.1        0.89        perf-profile.calltrace.cycles-pp.x64_sys_call.do_syscall_64.entry_SYSCALL_64_after_hwframe.write
>       1.72            -0.1        1.64        perf-profile.calltrace.cycles-pp.mutex_lock.pipe_write.vfs_write.ksys_write.do_syscall_64
>       1.67            -0.1        1.60        perf-profile.calltrace.cycles-pp.mutex_lock.pipe_read.vfs_read.ksys_read.do_syscall_64
>       1.18            -0.1        1.11        perf-profile.calltrace.cycles-pp.fput.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe.write
>       0.98            -0.1        0.90        perf-profile.calltrace.cycles-pp.mutex_unlock.pipe_read.vfs_read.ksys_read.do_syscall_64
>       1.17            -0.1        1.10 ±  2%  perf-profile.calltrace.cycles-pp.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.write
>       0.98            -0.1        0.92        perf-profile.calltrace.cycles-pp.x64_sys_call.do_syscall_64.entry_SYSCALL_64_after_hwframe.read
>       0.98            -0.1        0.92        perf-profile.calltrace.cycles-pp.mutex_unlock.pipe_write.vfs_write.ksys_write.do_syscall_64
>       0.97            -0.1        0.92        perf-profile.calltrace.cycles-pp.fput.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe.read
>       0.63 ±  3%      -0.1        0.58        perf-profile.calltrace.cycles-pp.testcase
>       0.00            +0.5        0.54 ±  4%  perf-profile.calltrace.cycles-pp.timestamp_truncate.current_time.inode_needs_update_time.file_update_time.pipe_write
>       0.00            +0.5        0.55 ±  5%  perf-profile.calltrace.cycles-pp.timestamp_truncate.current_time.atime_needs_update.touch_atime.pipe_read
>       0.00            +0.7        0.68 ± 11%  perf-profile.calltrace.cycles-pp.ktime_get_coarse_ts64.coarse_ctime.current_time.atime_needs_update.touch_atime
>      35.70            +0.9       36.58        perf-profile.calltrace.cycles-pp.entry_SYSCALL_64_after_hwframe.write
>      34.80            +0.9       35.74        perf-profile.calltrace.cycles-pp.do_syscall_64.entry_SYSCALL_64_after_hwframe.write
>      32.06            +1.0       33.08        perf-profile.calltrace.cycles-pp.entry_SYSCALL_64_after_hwframe.read
>      31.16            +1.1       32.24        perf-profile.calltrace.cycles-pp.do_syscall_64.entry_SYSCALL_64_after_hwframe.read
>       0.00            +1.1        1.10 ± 16%  perf-profile.calltrace.cycles-pp.coarse_ctime.current_time.inode_needs_update_time.file_update_time.pipe_write
>      30.51            +1.2       31.73        perf-profile.calltrace.cycles-pp.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe.write
>      25.27            +1.3       26.57        perf-profile.calltrace.cycles-pp.vfs_write.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe.write
>      27.06            +1.4       28.44        perf-profile.calltrace.cycles-pp.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe.read
>      22.04            +1.5       23.51        perf-profile.calltrace.cycles-pp.vfs_read.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe.read
>       0.00            +1.5        1.48 ±  3%  perf-profile.calltrace.cycles-pp.coarse_ctime.current_time.atime_needs_update.touch_atime.pipe_read
>      17.63            +1.8       19.44        perf-profile.calltrace.cycles-pp.pipe_write.vfs_write.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe
>      14.70            +2.0       16.71        perf-profile.calltrace.cycles-pp.pipe_read.vfs_read.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe
>       4.15            +2.3        6.50        perf-profile.calltrace.cycles-pp.touch_atime.pipe_read.vfs_read.ksys_read.do_syscall_64
>       1.79            +2.4        4.15        perf-profile.calltrace.cycles-pp.current_time.atime_needs_update.touch_atime.pipe_read.vfs_read
>       3.76            +2.4        6.13        perf-profile.calltrace.cycles-pp.atime_needs_update.touch_atime.pipe_read.vfs_read.ksys_read
>       2.04 ± 12%      +2.5        4.53 ±  5%  perf-profile.calltrace.cycles-pp.file_update_time.pipe_write.vfs_write.ksys_write.do_syscall_64
>       1.76 ± 14%      +2.5        4.26 ±  5%  perf-profile.calltrace.cycles-pp.inode_needs_update_time.file_update_time.pipe_write.vfs_write.ksys_write
>       0.00            +3.5        3.46 ±  6%  perf-profile.calltrace.cycles-pp.current_time.inode_needs_update_time.file_update_time.pipe_write.vfs_write
>      14.13            -0.8       13.36        perf-profile.children.cycles-pp.clear_bhb_loop
>       7.00            -0.4        6.60        perf-profile.children.cycles-pp.entry_SYSCALL_64
>       5.64            -0.4        5.28        perf-profile.children.cycles-pp.copy_page_from_iter
>       4.19            -0.3        3.94        perf-profile.children.cycles-pp._copy_from_iter
>       4.34            -0.2        4.08        perf-profile.children.cycles-pp.copy_page_to_iter
>       4.12            -0.2        3.88        perf-profile.children.cycles-pp.entry_SYSRETQ_unsafe_stack
>       3.42            -0.2        3.25        perf-profile.children.cycles-pp._copy_to_iter
>       3.51            -0.2        3.35        perf-profile.children.cycles-pp.mutex_lock
>       2.15            -0.2        1.99        perf-profile.children.cycles-pp.x64_sys_call
>      53.53            -0.2       53.38        perf-profile.children.cycles-pp.write
>       2.41            -0.2        2.26        perf-profile.children.cycles-pp.syscall_exit_to_user_mode
>       2.21            -0.1        2.07        perf-profile.children.cycles-pp.__wake_up_sync_key
>       2.16            -0.1        2.02        perf-profile.children.cycles-pp.fput
>       2.03            -0.1        1.90        perf-profile.children.cycles-pp.mutex_unlock
>       1.60            -0.1        1.50        perf-profile.children.cycles-pp._raw_spin_lock_irqsave
>       0.73 ±  4%      -0.1        0.67        perf-profile.children.cycles-pp.testcase
>       0.64 ±  4%      -0.0        0.60 ±  2%  perf-profile.children.cycles-pp.aa_file_perm
>       0.77            -0.0        0.74        perf-profile.children.cycles-pp.entry_SYSCALL_64_safe_stack
>       0.38            -0.0        0.35        perf-profile.children.cycles-pp.__x64_sys_read
>       0.40            -0.0        0.38        perf-profile.children.cycles-pp.__x64_sys_write
>       0.32            -0.0        0.30        perf-profile.children.cycles-pp.kill_fasync
>       0.16 ±  3%      -0.0        0.14 ±  2%  perf-profile.children.cycles-pp.make_vfsgid
>       0.30            -0.0        0.29        perf-profile.children.cycles-pp._raw_spin_unlock_irqrestore
>       0.00            +0.4        0.41 ± 26%  perf-profile.children.cycles-pp.set_normalized_timespec64
>       0.43 ± 13%      +0.7        1.14 ±  4%  perf-profile.children.cycles-pp.timestamp_truncate
>       0.00            +1.0        0.95 ±  4%  perf-profile.children.cycles-pp.ktime_get_coarse_with_offset
>       0.00            +1.1        1.06        perf-profile.children.cycles-pp.ns_to_timespec64
>       0.00            +1.2        1.17 ±  3%  perf-profile.children.cycles-pp.ktime_get_coarse_ts64
>      30.76            +1.2       31.97        perf-profile.children.cycles-pp.ksys_write
>      25.47            +1.3       26.75        perf-profile.children.cycles-pp.vfs_write
>      27.19            +1.4       28.55        perf-profile.children.cycles-pp.ksys_read
>      22.13            +1.4       23.57        perf-profile.children.cycles-pp.vfs_read
>      17.81            +1.8       19.60        perf-profile.children.cycles-pp.pipe_write
>      68.06            +1.9       69.94        perf-profile.children.cycles-pp.entry_SYSCALL_64_after_hwframe
>      15.02            +2.0       17.01        perf-profile.children.cycles-pp.pipe_read
>      66.19            +2.0       68.19        perf-profile.children.cycles-pp.do_syscall_64
>       4.24            +2.3        6.58        perf-profile.children.cycles-pp.touch_atime
>       3.86            +2.4        6.23        perf-profile.children.cycles-pp.atime_needs_update
>       1.88 ± 13%      +2.5        4.34 ±  5%  perf-profile.children.cycles-pp.inode_needs_update_time
>       2.11 ± 12%      +2.5        4.60 ±  5%  perf-profile.children.cycles-pp.file_update_time
>       0.00            +2.7        2.66 ±  6%  perf-profile.children.cycles-pp.coarse_ctime
>       1.82            +6.2        8.04 ±  2%  perf-profile.children.cycles-pp.current_time
>      14.05            -0.8       13.28        perf-profile.self.cycles-pp.clear_bhb_loop
>       1.06 ±  8%      -0.4        0.67        perf-profile.self.cycles-pp.inode_needs_update_time
>       5.00 ±  3%      -0.3        4.67 ±  3%  perf-profile.self.cycles-pp.vfs_write
>       4.10 ±  3%      -0.3        3.78 ±  3%  perf-profile.self.cycles-pp.vfs_read
>       3.71            -0.2        3.48 ±  2%  perf-profile.self.cycles-pp._copy_from_iter
>       3.98            -0.2        3.75        perf-profile.self.cycles-pp.entry_SYSRETQ_unsafe_stack
>       2.89            -0.2        2.68        perf-profile.self.cycles-pp.do_syscall_64
>       3.38            -0.2        3.17        perf-profile.self.cycles-pp.read
>       2.91            -0.2        2.71 ±  2%  perf-profile.self.cycles-pp._copy_to_iter
>       3.48            -0.2        3.28        perf-profile.self.cycles-pp.write
>       3.06            -0.2        2.88        perf-profile.self.cycles-pp.entry_SYSCALL_64
>       1.76            -0.2        1.60        perf-profile.self.cycles-pp.atime_needs_update
>       2.03            -0.2        1.88        perf-profile.self.cycles-pp.x64_sys_call
>       1.90            -0.1        1.78        perf-profile.self.cycles-pp.entry_SYSCALL_64_after_hwframe
>       2.18            -0.1        2.07        perf-profile.self.cycles-pp.mutex_lock
>       1.93            -0.1        1.82        perf-profile.self.cycles-pp.mutex_unlock
>       1.92            -0.1        1.81        perf-profile.self.cycles-pp.fput
>       1.46            -0.1        1.36        perf-profile.self.cycles-pp.syscall_exit_to_user_mode
>       1.54            -0.1        1.45        perf-profile.self.cycles-pp._raw_spin_lock_irqsave
>       1.06            -0.1        0.98        perf-profile.self.cycles-pp.ksys_read
>       1.19            -0.1        1.11        perf-profile.self.cycles-pp.ksys_write
>       0.58 ±  4%      -0.1        0.53        perf-profile.self.cycles-pp.testcase
>       0.77            -0.0        0.74        perf-profile.self.cycles-pp.entry_SYSCALL_64_safe_stack
>       0.38            -0.0        0.36 ±  2%  perf-profile.self.cycles-pp.touch_atime
>       0.30            -0.0        0.28        perf-profile.self.cycles-pp.__x64_sys_write
>       0.35            -0.0        0.33        perf-profile.self.cycles-pp.__wake_up_sync_key
>       0.28            -0.0        0.26        perf-profile.self.cycles-pp.__x64_sys_read
>       0.25            -0.0        0.24        perf-profile.self.cycles-pp.kill_fasync
>       0.26            +0.0        0.29        perf-profile.self.cycles-pp.file_update_time
>       0.00            +0.4        0.40 ± 25%  perf-profile.self.cycles-pp.set_normalized_timespec64
>       0.40 ± 11%      +0.7        1.06 ±  4%  perf-profile.self.cycles-pp.timestamp_truncate
>       0.00            +0.9        0.89        perf-profile.self.cycles-pp.ns_to_timespec64
>       0.00            +0.9        0.91 ±  4%  perf-profile.self.cycles-pp.ktime_get_coarse_with_offset
>       0.00            +1.1        1.10 ±  5%  perf-profile.self.cycles-pp.coarse_ctime
>       0.00            +1.1        1.11 ±  3%  perf-profile.self.cycles-pp.ktime_get_coarse_ts64
>       1.06 ±  5%      +1.4        2.44 ±  2%  perf-profile.self.cycles-pp.current_time
> 
> 
> ***************************************************************************************************
> lkp-icl-2sp2: 128 threads 2 sockets Intel(R) Xeon(R) Gold 6338 CPU @ 2.00GHz (Ice Lake) with 256G memory
> =========================================================================================
> compiler/cpufreq_governor/ipc/iterations/kconfig/mode/nr_threads/rootfs/tbox_group/testcase:
>   gcc-12/performance/pipe/4/x86_64-rhel-8.3/threads/800%/debian-12-x86_64-20240206.cgz/lkp-icl-2sp2/hackbench
> 
> commit: 
>   v6.12-rc1
>   2e4c6e78f4 ("fs: add infrastructure for multigrain timestamps")
> 
>        v6.12-rc1 2e4c6e78f41afefb7a2b825b7aa 
> ---------------- --------------------------- 
>          %stddev     %change         %stddev
>              \          |                \  
>     561190 ± 49%     -33.6%     372781 ± 77%  numa-meminfo.node0.SUnreclaim
>     137108 ± 48%     -35.9%      87915 ± 74%  numa-vmstat.node0.nr_slab_unreclaimable
>  2.263e+08 ±  3%     -13.7%  1.954e+08 ±  7%  perf-stat.i.cache-misses
>  7.636e+08 ±  5%     -14.5%  6.531e+08 ±  9%  perf-stat.i.cache-references
>      18.89 ± 18%     -31.6%      12.92 ± 21%  perf-stat.i.metric.K/sec
>     246747            -3.4%     238348        proc-vmstat.nr_anon_pages
>     383468 ± 36%     -19.0%     310490 ±  2%  proc-vmstat.nr_inactive_anon
>       2246 ±  3%      -4.9%       2135 ±  2%  proc-vmstat.nr_page_table_pages
>     383468 ± 36%     -19.0%     310490 ±  2%  proc-vmstat.nr_zone_inactive_anon
>    1231417            -4.5%    1175946        hackbench.throughput
>    1179456            -3.7%    1136004        hackbench.throughput_avg
>    1231417            -4.5%    1175946        hackbench.throughput_best
>       5279            +4.8%       5530        hackbench.time.system_time
>     954.46            -0.8%     946.55        hackbench.time.user_time
>       0.12 ±  8%     -36.0%       0.08 ± 23%  sched_debug.cfs_rq:/.h_nr_running.avg
>       0.33 ±  4%     -21.5%       0.26 ± 11%  sched_debug.cfs_rq:/.h_nr_running.stddev
>      77.21 ± 38%     -50.7%      38.06 ± 60%  sched_debug.cfs_rq:/.load_avg.avg
>       1421 ± 27%     -49.9%     712.70 ± 26%  sched_debug.cfs_rq:/.load_avg.max
>     251.26 ± 25%     -45.5%     137.06 ± 44%  sched_debug.cfs_rq:/.load_avg.stddev
>       0.12 ±  8%     -36.0%       0.08 ± 23%  sched_debug.cfs_rq:/.nr_running.avg
>       0.33 ±  4%     -21.5%       0.26 ± 11%  sched_debug.cfs_rq:/.nr_running.stddev
>     221.71 ± 26%     -49.9%     111.18 ± 60%  sched_debug.cfs_rq:/.removed.load_avg.stddev
>     253.34 ±  7%     -37.5%     158.42 ± 28%  sched_debug.cfs_rq:/.runnable_avg.avg
>     297.62 ±  4%     -20.9%     235.28 ± 11%  sched_debug.cfs_rq:/.runnable_avg.stddev
>     252.17 ±  7%     -37.6%     157.31 ± 28%  sched_debug.cfs_rq:/.util_avg.avg
>     297.28 ±  4%     -21.0%     234.70 ± 11%  sched_debug.cfs_rq:/.util_avg.stddev
>     335.27 ± 11%     -33.2%     224.09 ± 23%  sched_debug.cpu.curr->pid.avg
>     941.56 ±  4%     -10.3%     844.57 ±  6%  sched_debug.cpu.curr->pid.stddev
>       0.11 ± 12%     -35.9%       0.07 ± 25%  sched_debug.cpu.nr_running.avg
>       0.32 ±  6%     -21.6%       0.25 ± 12%  sched_debug.cpu.nr_running.stddev
>     131.67 ±  4%    +1e+05%     134061 ± 52%  sched_debug.cpu.nr_switches.min
>       0.01 ± 28%     -64.0%       0.00 ± 33%  sched_debug.cpu.nr_uninterruptible.avg
>      12.54 ± 84%     -12.5        0.00        perf-profile.calltrace.cycles-pp.devkmsg_emit.devkmsg_write.vfs_write.ksys_write.do_syscall_64
>      12.54 ± 84%     -12.5        0.00        perf-profile.calltrace.cycles-pp.devkmsg_write.vfs_write.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe
>      12.54 ± 84%     -12.5        0.00        perf-profile.calltrace.cycles-pp.vprintk_emit.devkmsg_emit.devkmsg_write.vfs_write.ksys_write
>      12.66 ± 83%     -12.4        0.29 ±129%  perf-profile.calltrace.cycles-pp.do_syscall_64.entry_SYSCALL_64_after_hwframe.write
>      12.66 ± 83%     -12.4        0.29 ±129%  perf-profile.calltrace.cycles-pp.entry_SYSCALL_64_after_hwframe.write
>      12.66 ± 83%     -12.4        0.29 ±129%  perf-profile.calltrace.cycles-pp.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe.write
>      12.66 ± 83%     -12.4        0.29 ±129%  perf-profile.calltrace.cycles-pp.write
>      11.78 ± 84%     -11.8        0.00        perf-profile.calltrace.cycles-pp.console_unlock.vprintk_emit.devkmsg_emit.devkmsg_write.vfs_write
>      11.78 ± 84%     -11.8        0.00        perf-profile.calltrace.cycles-pp.console_flush_all.console_unlock.vprintk_emit.devkmsg_emit.devkmsg_write
>      11.10 ± 84%     -11.1        0.00        perf-profile.calltrace.cycles-pp.serial8250_console_write.console_flush_all.console_unlock.vprintk_emit.devkmsg_emit
>       7.42 ± 61%      -5.0        2.40 ± 83%  perf-profile.calltrace.cycles-pp.io_serial_in.wait_for_lsr.serial8250_console_write.console_flush_all.console_unlock
>       0.30 ±150%      +1.1        1.43 ± 43%  perf-profile.calltrace.cycles-pp.number.vsnprintf.seq_printf.show_interrupts.seq_read_iter
>       8.40 ± 41%      +5.9       14.30 ± 15%  perf-profile.calltrace.cycles-pp.entry_SYSCALL_64_after_hwframe.read
>       8.36 ± 42%      +5.9       14.30 ± 15%  perf-profile.calltrace.cycles-pp.do_syscall_64.entry_SYSCALL_64_after_hwframe.read
>       8.60 ± 40%      +5.9       14.54 ± 16%  perf-profile.calltrace.cycles-pp.read
>       8.23 ± 41%      +6.1       14.30 ± 15%  perf-profile.calltrace.cycles-pp.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe.read
>       8.10 ± 41%      +6.1       14.18 ± 14%  perf-profile.calltrace.cycles-pp.vfs_read.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe.read
>      12.54 ± 84%     -12.5        0.00        perf-profile.children.cycles-pp.devkmsg_emit
>      12.54 ± 84%     -12.5        0.00        perf-profile.children.cycles-pp.devkmsg_write
>       9.02 ± 58%      -6.3        2.74 ± 83%  perf-profile.children.cycles-pp.io_serial_in
>       1.49 ± 35%      -0.7        0.77 ± 39%  perf-profile.children.cycles-pp.d_alloc_parallel
>       1.20 ± 30%      -0.6        0.57 ± 26%  perf-profile.children.cycles-pp.d_alloc
>       7.51 ±101%      -0.5        7.04 ±123%  perf-profile.children.cycles-pp.__ordered_events__flush
>       0.70 ± 38%      -0.4        0.30 ± 72%  perf-profile.children.cycles-pp.lookup_open
>       3.15 ±104%      -0.4        2.79 ±127%  perf-profile.children.cycles-pp.build_id__mark_dso_hit
>       6.78 ±103%      -0.0        6.75 ±122%  perf-profile.children.cycles-pp.perf_session__deliver_event
>       0.11 ±119%      +0.3        0.41 ± 34%  perf-profile.children.cycles-pp.free_unref_page
>       0.54 ± 35%      +0.9        1.39 ± 48%  perf-profile.children.cycles-pp.__dentry_kill
>       0.70 ± 47%      +1.1        1.81 ± 36%  perf-profile.children.cycles-pp.dput
>       7.71 ± 43%      +5.8       13.46 ± 11%  perf-profile.children.cycles-pp.seq_read_iter
>       8.60 ± 40%      +5.9       14.54 ± 16%  perf-profile.children.cycles-pp.read
>       8.29 ± 40%      +6.0       14.30 ± 15%  perf-profile.children.cycles-pp.ksys_read
>       8.15 ± 40%      +6.1       14.23 ± 13%  perf-profile.children.cycles-pp.vfs_read
>      10.49 ± 58%     +11.5       21.94 ± 29%  perf-profile.children.cycles-pp.__cmd_record
>       9.02 ± 58%      -6.3        2.74 ± 83%  perf-profile.self.cycles-pp.io_serial_in
>       0.15 ±107%      +1.0        1.19 ± 53%  perf-profile.self.cycles-pp.show_interrupts
>       0.01 ±169%    +635.4%       0.05 ± 46%  perf-sched.sch_delay.avg.ms.__cond_resched.smpboot_thread_fn.kthread.ret_from_fork.ret_from_fork_asm
>     506.03 ±223%   +1038.0%       5758 ± 92%  perf-sched.sch_delay.avg.ms.__cond_resched.switch_task_namespaces.do_exit.__x64_sys_exit.x64_sys_call
>       2527 ± 37%     +34.6%       3402 ± 17%  perf-sched.sch_delay.max.ms.__cond_resched.__wait_for_common.affine_move_task.__set_cpus_allowed_ptr.__sched_setaffinity
>       5433 ± 62%    +111.9%      11512 ±  8%  perf-sched.sch_delay.max.ms.__cond_resched.mutex_lock.pipe_read.vfs_read.ksys_read
>       8727 ± 28%     +41.7%      12368 ±  6%  perf-sched.sch_delay.max.ms.__cond_resched.mutex_lock.pipe_write.vfs_write.ksys_write
>       0.16 ±221%   +1222.8%       2.11 ±101%  perf-sched.sch_delay.max.ms.__cond_resched.smpboot_thread_fn.kthread.ret_from_fork.ret_from_fork_asm
>       1543 ±223%    +338.6%       6770 ± 82%  perf-sched.sch_delay.max.ms.__cond_resched.switch_task_namespaces.do_exit.__x64_sys_exit.x64_sys_call
>       8967 ± 26%     +36.1%      12200 ±  7%  perf-sched.sch_delay.max.ms.irqentry_exit_to_user_mode.asm_sysvec_apic_timer_interrupt.[unknown].[unknown]
>      65.76 ± 67%   +3435.0%       2324 ±184%  perf-sched.sch_delay.max.ms.irqentry_exit_to_user_mode.asm_sysvec_reschedule_ipi.[unknown].[unknown]
>       9232 ± 26%     +36.5%      12600 ±  6%  perf-sched.sch_delay.max.ms.pipe_read.vfs_read.ksys_read.do_syscall_64
>       9419 ± 25%     +33.7%      12597 ±  5%  perf-sched.sch_delay.max.ms.pipe_write.vfs_write.ksys_write.do_syscall_64
>       8740 ± 27%     +43.0%      12498 ±  4%  perf-sched.sch_delay.max.ms.schedule_preempt_disabled.__mutex_lock.constprop.0.pipe_write
>       8472 ± 39%     +48.9%      12613 ±  5%  perf-sched.sch_delay.max.ms.schedule_preempt_disabled.rwsem_down_read_slowpath.down_read.exit_mm
>       9034 ± 27%     +40.2%      12667 ±  4%  perf-sched.sch_delay.max.ms.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.[unknown]
>       9461 ± 25%     +36.4%      12905 ±  4%  perf-sched.total_sch_delay.max.ms
>      18705 ± 25%     +37.6%      25730 ±  5%  perf-sched.total_wait_and_delay.max.ms
>       9525 ± 23%     +38.6%      13204 ±  7%  perf-sched.total_wait_time.max.ms
>      17493 ± 28%     +41.3%      24713 ±  6%  perf-sched.wait_and_delay.max.ms.__cond_resched.mutex_lock.pipe_write.vfs_write.ksys_write
>      17105 ± 27%     +42.1%      24316 ±  8%  perf-sched.wait_and_delay.max.ms.irqentry_exit_to_user_mode.asm_sysvec_apic_timer_interrupt.[unknown].[unknown]
>      17952 ± 26%     +39.7%      25074 ±  6%  perf-sched.wait_and_delay.max.ms.pipe_read.vfs_read.ksys_read.do_syscall_64
>      18587 ± 25%     +36.2%      25322 ±  5%  perf-sched.wait_and_delay.max.ms.pipe_write.vfs_write.ksys_write.do_syscall_64
>      17333 ± 29%     +44.3%      25016 ±  4%  perf-sched.wait_and_delay.max.ms.schedule_preempt_disabled.__mutex_lock.constprop.0.pipe_write
>      16951 ± 39%     +48.4%      25149 ±  5%  perf-sched.wait_and_delay.max.ms.schedule_preempt_disabled.rwsem_down_read_slowpath.down_read.exit_mm
>      17996 ± 27%     +40.2%      25232 ±  5%  perf-sched.wait_and_delay.max.ms.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.[unknown]
>     163.71 ±203%    +576.0%       1106 ± 90%  perf-sched.wait_time.avg.ms.__cond_resched.pipe_write.vfs_write.ksys_write.do_syscall_64
>      18.58 ±223%    +986.5%     201.88 ± 64%  perf-sched.wait_time.avg.ms.__cond_resched.smpboot_thread_fn.kthread.ret_from_fork.ret_from_fork_asm
>       1478 ±223%    +391.5%       7267 ± 71%  perf-sched.wait_time.avg.ms.__cond_resched.switch_task_namespaces.do_exit.__x64_sys_exit.x64_sys_call
>       0.15 ±223%   +2351.7%       3.74 ± 70%  perf-sched.wait_time.avg.ms.do_task_dead.do_exit.__x64_sys_exit.x64_sys_call.do_syscall_64
>       2619 ± 27%     +29.9%       3402 ± 17%  perf-sched.wait_time.max.ms.__cond_resched.__wait_for_common.affine_move_task.__set_cpus_allowed_ptr.__sched_setaffinity
>       1593 ±223%    +360.5%       7337 ± 81%  perf-sched.wait_time.max.ms.__cond_resched.mmput.exit_mm.do_exit.__x64_sys_exit
>       7248 ± 40%     +60.1%      11605 ±  8%  perf-sched.wait_time.max.ms.__cond_resched.mutex_lock.pipe_read.vfs_read.ksys_read
>       8913 ± 27%     +41.0%      12567 ±  8%  perf-sched.wait_time.max.ms.__cond_resched.mutex_lock.pipe_write.vfs_write.ksys_write
>       1658 ±217%    +301.5%       6658 ± 81%  perf-sched.wait_time.max.ms.__cond_resched.pipe_write.vfs_write.ksys_write.do_syscall_64
>       1671 ±223%    +498.0%       9998 ± 50%  perf-sched.wait_time.max.ms.__cond_resched.smpboot_thread_fn.kthread.ret_from_fork.ret_from_fork_asm
>       1581 ±223%    +473.2%       9064 ± 50%  perf-sched.wait_time.max.ms.__cond_resched.switch_task_namespaces.do_exit.__x64_sys_exit.x64_sys_call
>       8915 ± 25%     +39.1%      12405 ±  7%  perf-sched.wait_time.max.ms.irqentry_exit_to_user_mode.asm_sysvec_apic_timer_interrupt.[unknown].[unknown]
>       9200 ± 26%     +40.4%      12920 ±  7%  perf-sched.wait_time.max.ms.pipe_read.vfs_read.ksys_read.do_syscall_64
>       9433 ± 23%     +36.3%      12857 ±  7%  perf-sched.wait_time.max.ms.pipe_write.vfs_write.ksys_write.do_syscall_64
>       8838 ± 28%     +42.4%      12582 ±  4%  perf-sched.wait_time.max.ms.schedule_preempt_disabled.__mutex_lock.constprop.0.pipe_write
>       8520 ± 39%     +48.5%      12654 ±  5%  perf-sched.wait_time.max.ms.schedule_preempt_disabled.rwsem_down_read_slowpath.down_read.exit_mm
>       8819 ± 26%     +45.3%      12815 ±  7%  perf-sched.wait_time.max.ms.smpboot_thread_fn.kthread.ret_from_fork.ret_from_fork_asm
>       9176 ± 26%     +39.6%      12813 ±  7%  perf-sched.wait_time.max.ms.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.[unknown]
>       8699 ± 25%     +48.7%      12937 ±  8%  perf-sched.wait_time.max.ms.worker_thread.kthread.ret_from_fork.ret_from_fork_asm
> 
> 
> 
> ***************************************************************************************************
> lkp-skl-fpga01: 104 threads 2 sockets (Skylake) with 192G memory
> =========================================================================================
> compiler/cpufreq_governor/kconfig/mode/nr_task/rootfs/tbox_group/test/testcase:
>   gcc-12/performance/x86_64-rhel-8.3/process/100%/debian-12-x86_64-20240206.cgz/lkp-skl-fpga01/pipe1/will-it-scale
> 
> commit: 
>   v6.12-rc1
>   2e4c6e78f4 ("fs: add infrastructure for multigrain timestamps")
> 
>        v6.12-rc1 2e4c6e78f41afefb7a2b825b7aa 
> ---------------- --------------------------- 
>          %stddev     %change         %stddev
>              \          |                \  
>     816.00 ±  6%     -11.4%     722.72 ±  5%  sched_debug.cfs_rq:/.util_est.max
>   33816990            -2.0%   33148227        will-it-scale.104.processes
>     325162            -2.0%     318732        will-it-scale.per_process_ops
>   33816990            -2.0%   33148227        will-it-scale.workload
>       0.70 ± 63%     +68.4%       1.18 ±  4%  perf-sched.sch_delay.avg.ms.worker_thread.kthread.ret_from_fork.ret_from_fork_asm
>     506.90 ± 11%     -14.5%     433.43 ±  3%  perf-sched.wait_and_delay.avg.ms.worker_thread.kthread.ret_from_fork.ret_from_fork_asm
>     281.17 ± 50%     -51.7%     135.83 ± 19%  perf-sched.wait_and_delay.count.irqentry_exit_to_user_mode.asm_sysvec_apic_timer_interrupt.[unknown]
>       1000           -79.4%     206.38 ±171%  perf-sched.wait_and_delay.max.ms.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.[unknown]
>       2.27 ± 52%  +18623.0%     424.45 ±117%  perf-sched.wait_time.avg.ms.__cond_resched.shmem_inode_acct_blocks.shmem_alloc_and_add_folio.shmem_get_folio_gfp.shmem_write_begin
>     506.20 ± 11%     -14.6%     432.25 ±  3%  perf-sched.wait_time.avg.ms.worker_thread.kthread.ret_from_fork.ret_from_fork_asm
>     999.76           -80.5%     195.04 ±183%  perf-sched.wait_time.max.ms.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.[unknown]
>    1.3e+10            +8.0%  1.404e+10        perf-stat.i.branch-instructions
>       1.10            -0.1        1.00        perf-stat.i.branch-miss-rate%
>       4.14            -6.8%       3.86        perf-stat.i.cpi
>     425295            -5.1%     403763        perf-stat.i.cycles-between-cache-misses
>   6.96e+10            +7.2%  7.461e+10        perf-stat.i.instructions
>       0.24            +7.0%       0.26        perf-stat.i.ipc
>       0.01 ±  2%      -7.0%       0.01 ±  5%  perf-stat.overall.MPKI
>       1.09            -0.1        0.99        perf-stat.overall.branch-miss-rate%
>       4.15            -6.8%       3.87        perf-stat.overall.cpi
>       0.24            +7.3%       0.26        perf-stat.overall.ipc
>     622217            +9.4%     680897        perf-stat.overall.path-length
>  1.296e+10            +8.0%    1.4e+10        perf-stat.ps.branch-instructions
>  6.937e+10            +7.2%  7.436e+10        perf-stat.ps.instructions
>  2.104e+13            +7.3%  2.257e+13        perf-stat.total.instructions
>       1.62            -0.5        1.15        perf-profile.calltrace.cycles-pp.mutex_lock.pipe_write.vfs_write.ksys_write.do_syscall_64
>      11.67            -0.3       11.34        perf-profile.calltrace.cycles-pp.syscall_return_via_sysret.write
>      11.68            -0.1       11.56        perf-profile.calltrace.cycles-pp.syscall_return_via_sysret.read
>       8.36            -0.1        8.25        perf-profile.calltrace.cycles-pp.entry_SYSRETQ_unsafe_stack.write
>       4.06            -0.1        3.95        perf-profile.calltrace.cycles-pp.entry_SYSCALL_64.write
>       1.46            -0.1        1.37        perf-profile.calltrace.cycles-pp.mutex_lock.pipe_read.vfs_read.ksys_read.do_syscall_64
>       4.02            -0.1        3.93        perf-profile.calltrace.cycles-pp.entry_SYSCALL_64.read
>       0.73            +0.0        0.75        perf-profile.calltrace.cycles-pp.security_file_permission.rw_verify_area.vfs_write.ksys_write.do_syscall_64
>       0.65            +0.0        0.68        perf-profile.calltrace.cycles-pp.apparmor_file_permission.security_file_permission.rw_verify_area.vfs_write.ksys_write
>       0.80            +0.0        0.84        perf-profile.calltrace.cycles-pp.rw_verify_area.vfs_write.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe
>       0.92            +0.0        0.97        perf-profile.calltrace.cycles-pp.fdget_pos.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe.read
>       0.87 ±  2%      +0.2        1.02 ±  2%  perf-profile.calltrace.cycles-pp.fdget_pos.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe.write
>       1.66 ±  2%      +0.2        1.85 ±  2%  perf-profile.calltrace.cycles-pp.copy_page_to_iter.pipe_read.vfs_read.ksys_read.do_syscall_64
>       1.22 ±  2%      +0.3        1.50 ±  2%  perf-profile.calltrace.cycles-pp._copy_to_iter.copy_page_to_iter.pipe_read.vfs_read.ksys_read
>      21.79            +0.4       22.14        perf-profile.calltrace.cycles-pp.entry_SYSCALL_64_after_hwframe.read
>       1.39 ±  2%      +0.5        1.86        perf-profile.calltrace.cycles-pp._copy_from_iter.copy_page_from_iter.pipe_write.vfs_write.ksys_write
>       1.92            +0.5        2.40        perf-profile.calltrace.cycles-pp.copy_page_from_iter.pipe_write.vfs_write.ksys_write.do_syscall_64
>      14.97            +0.5       15.47        perf-profile.calltrace.cycles-pp.do_syscall_64.entry_SYSCALL_64_after_hwframe.read
>      22.36            +0.6       22.90        perf-profile.calltrace.cycles-pp.entry_SYSCALL_64_after_hwframe.write
>       7.84            +0.6        8.43        perf-profile.calltrace.cycles-pp.pipe_read.vfs_read.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe
>       0.00            +0.6        0.59 ±  4%  perf-profile.calltrace.cycles-pp.rep_movs_alternative._copy_to_iter.copy_page_to_iter.pipe_read.vfs_read
>       0.00            +0.6        0.60 ±  2%  perf-profile.calltrace.cycles-pp.rep_movs_alternative._copy_from_iter.copy_page_from_iter.pipe_write.vfs_write
>       1.69            +0.7        2.41        perf-profile.calltrace.cycles-pp.touch_atime.pipe_read.vfs_read.ksys_read.do_syscall_64
>       1.40            +0.8        2.16        perf-profile.calltrace.cycles-pp.atime_needs_update.touch_atime.pipe_read.vfs_read.ksys_read
>      10.52            +0.8       11.29        perf-profile.calltrace.cycles-pp.vfs_read.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe.read
>       0.56            +0.8        1.34        perf-profile.calltrace.cycles-pp.current_time.atime_needs_update.touch_atime.pipe_read.vfs_read
>       0.52            +0.8        1.34        perf-profile.calltrace.cycles-pp.inode_needs_update_time.file_update_time.pipe_write.vfs_write.ksys_write
>      15.50            +0.8       16.31        perf-profile.calltrace.cycles-pp.do_syscall_64.entry_SYSCALL_64_after_hwframe.write
>       0.65            +0.9        1.56        perf-profile.calltrace.cycles-pp.file_update_time.pipe_write.vfs_write.ksys_write.do_syscall_64
>      12.82            +0.9       13.74        perf-profile.calltrace.cycles-pp.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe.write
>      12.00            +0.9       12.92        perf-profile.calltrace.cycles-pp.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe.read
>       0.00            +1.0        1.02        perf-profile.calltrace.cycles-pp.current_time.inode_needs_update_time.file_update_time.pipe_write.vfs_write
>      11.10            +1.1       12.18        perf-profile.calltrace.cycles-pp.vfs_write.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe.write
>       8.12            +1.3        9.39        perf-profile.calltrace.cycles-pp.pipe_write.vfs_write.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe
>       3.13            -0.6        2.56        perf-profile.children.cycles-pp.mutex_lock
>       1.40            -0.5        0.90 ±  2%  perf-profile.children.cycles-pp.__cond_resched
>      23.52            -0.5       23.07        perf-profile.children.cycles-pp.syscall_return_via_sysret
>       1.35 ±  3%      -0.3        1.01        perf-profile.children.cycles-pp.syscall_exit_to_user_mode
>       0.88 ±  3%      -0.3        0.54 ±  2%  perf-profile.children.cycles-pp.rcu_all_qs
>       0.66 ±  6%      -0.2        0.41 ±  2%  perf-profile.children.cycles-pp.syscall_exit_to_user_mode_prepare
>       8.92            -0.2        8.68        perf-profile.children.cycles-pp.entry_SYSCALL_64
>      17.87            -0.2       17.63        perf-profile.children.cycles-pp.entry_SYSRETQ_unsafe_stack
>       0.00            +0.1        0.11 ±  8%  perf-profile.children.cycles-pp.set_normalized_timespec64
>       0.15 ±  2%      +0.1        0.28 ± 12%  perf-profile.children.cycles-pp.timestamp_truncate
>       1.68 ±  2%      +0.2        1.87 ±  2%  perf-profile.children.cycles-pp.copy_page_to_iter
>       1.80            +0.2        2.00        perf-profile.children.cycles-pp.fdget_pos
>       1.32            +0.3        1.59 ±  2%  perf-profile.children.cycles-pp._copy_to_iter
>       0.00            +0.3        0.28        perf-profile.children.cycles-pp.ktime_get_coarse_with_offset
>       0.00            +0.3        0.32        perf-profile.children.cycles-pp.ktime_get_coarse_ts64
>       0.00            +0.3        0.35 ±  2%  perf-profile.children.cycles-pp.ns_to_timespec64
>       1.95            +0.5        2.42        perf-profile.children.cycles-pp.copy_page_from_iter
>       1.49 ±  2%      +0.5        1.98        perf-profile.children.cycles-pp._copy_from_iter
>       0.65            +0.6        1.22 ±  2%  perf-profile.children.cycles-pp.rep_movs_alternative
>       7.98            +0.6        8.56        perf-profile.children.cycles-pp.pipe_read
>       1.72            +0.7        2.43        perf-profile.children.cycles-pp.touch_atime
>       0.00            +0.7        0.74        perf-profile.children.cycles-pp.coarse_ctime
>       1.44            +0.8        2.20        perf-profile.children.cycles-pp.atime_needs_update
>      10.55            +0.8       11.32        perf-profile.children.cycles-pp.vfs_read
>       0.56            +0.8        1.37        perf-profile.children.cycles-pp.inode_needs_update_time
>      44.44            +0.9       45.34        perf-profile.children.cycles-pp.entry_SYSCALL_64_after_hwframe
>       0.67            +0.9        1.58        perf-profile.children.cycles-pp.file_update_time
>      12.86            +0.9       13.77        perf-profile.children.cycles-pp.ksys_write
>      12.02            +0.9       12.94        perf-profile.children.cycles-pp.ksys_read
>      11.16            +1.1       12.24        perf-profile.children.cycles-pp.vfs_write
>       8.18            +1.3        9.43        perf-profile.children.cycles-pp.pipe_write
>      30.60            +1.3       31.91        perf-profile.children.cycles-pp.do_syscall_64
>       0.57            +1.9        2.51        perf-profile.children.cycles-pp.current_time
>      23.47            -0.5       23.01        perf-profile.self.cycles-pp.syscall_return_via_sysret
>      14.02            -0.4       13.60        perf-profile.self.cycles-pp.entry_SYSCALL_64_after_hwframe
>       0.84 ±  3%      -0.3        0.50 ±  3%  perf-profile.self.cycles-pp.rcu_all_qs
>       0.82 ±  4%      -0.3        0.50 ±  2%  perf-profile.self.cycles-pp.ksys_write
>      17.70            -0.2       17.46        perf-profile.self.cycles-pp.entry_SYSRETQ_unsafe_stack
>       0.61 ±  6%      -0.2        0.38 ±  4%  perf-profile.self.cycles-pp.syscall_exit_to_user_mode_prepare
>       7.83            -0.2        7.61        perf-profile.self.cycles-pp.entry_SYSCALL_64
>       2.15            -0.2        1.94        perf-profile.self.cycles-pp.vfs_write
>       1.88 ±  2%      -0.2        1.70        perf-profile.self.cycles-pp.pipe_read
>       0.52 ±  3%      -0.2        0.37 ±  3%  perf-profile.self.cycles-pp.__cond_resched
>       0.69            -0.1        0.58 ±  2%  perf-profile.self.cycles-pp.syscall_exit_to_user_mode
>       0.35 ±  3%      -0.1        0.27        perf-profile.self.cycles-pp.copy_page_to_iter
>       0.80            -0.1        0.72        perf-profile.self.cycles-pp.atime_needs_update
>       0.34 ±  2%      -0.1        0.28        perf-profile.self.cycles-pp.inode_needs_update_time
>       0.26 ±  2%      -0.0        0.21 ±  3%  perf-profile.self.cycles-pp.touch_atime
>       0.46            -0.0        0.45        perf-profile.self.cycles-pp.copy_page_from_iter
>       0.10 ±  4%      +0.1        0.20        perf-profile.self.cycles-pp.file_update_time
>       0.54 ±  2%      +0.1        0.64 ±  3%  perf-profile.self.cycles-pp.ksys_read
>       0.00            +0.1        0.11 ±  8%  perf-profile.self.cycles-pp.set_normalized_timespec64
>       0.14 ±  3%      +0.1        0.26 ± 14%  perf-profile.self.cycles-pp.timestamp_truncate
>       1.28 ±  2%      +0.2        1.45        perf-profile.self.cycles-pp._copy_from_iter
>       1.48            +0.2        1.67 ±  2%  perf-profile.self.cycles-pp.vfs_read
>       1.80            +0.2        1.99        perf-profile.self.cycles-pp.fdget_pos
>       0.00            +0.3        0.26        perf-profile.self.cycles-pp.ktime_get_coarse_with_offset
>       0.00            +0.3        0.26        perf-profile.self.cycles-pp.ns_to_timespec64
>       0.00            +0.3        0.30        perf-profile.self.cycles-pp.ktime_get_coarse_ts64
>       0.00            +0.3        0.33        perf-profile.self.cycles-pp.coarse_ctime
>       2.29 ±  2%      +0.4        2.72        perf-profile.self.cycles-pp.pipe_write
>       0.48            +0.6        1.04 ±  3%  perf-profile.self.cycles-pp.rep_movs_alternative
>       0.33            +0.6        0.95 ±  5%  perf-profile.self.cycles-pp.current_time
> 
> 
> 
> 
> 
> 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.
> 
> 

-- 
Jeff Layton <jlayton@xxxxxxxxxx>





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