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Message-ID: <202511281428.bfcbd5a8-lkp@intel.com>
Date: Fri, 28 Nov 2025 14:56:32 +0800
From: kernel test robot <oliver.sang@...el.com>
To: Peter Zijlstra <peterz@...radead.org>
CC: <oe-lkp@...ts.linux.dev>, <lkp@...el.com>, <linux-kernel@...r.kernel.org>,
<x86@...nel.org>, Joseph Salisbury <joseph.salisbury@...cle.com>, Adam Li
<adamli@...amperecomputing.com>, Dietmar Eggemann <dietmar.eggemann@....com>,
Hazem Mohamed Abuelfotoh <abuehaze@...zon.com>, Chris Mason <clm@...a.com>,
<aubrey.li@...ux.intel.com>, <yu.c.chen@...el.com>, <oliver.sang@...el.com>
Subject: [tip:sched/core] [sched/fair] d206fbad93: hackbench.throughput
6.5% regression
Hello,
for the change reverted by this commit, we reported several regressions before
[1][2][3] majorly for unixbench tests.
[1] https://lore.kernel.org/all/202507150846.538fc133-lkp@intel.com/
[2] https://lore.kernel.org/all/202507281046.e71b853a-lkp@intel.com/
[3] https://lore.kernel.org/all/202508150416.d7153a48-lkp@intel.com/
but now, for d206fbad93, we also capture a regression in hackbench tests.
below report is just FYI what's the possible performance impact of this revert
commit.
kernel test robot noticed a 6.5% regression of hackbench.throughput on:
commit: d206fbad9328ddb68ebabd7cf7413392acd38081 ("sched/fair: Revert max_newidle_lb_cost bump")
https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git sched/core
[still regression on linux-next/master ef68bf704646690aba5e81c2f7be8d6ef13d7ad8]
testcase: hackbench
config: x86_64-rhel-9.4
compiler: gcc-14
test machine: 64 threads 2 sockets Intel(R) Xeon(R) Gold 6346 CPU @ 3.10GHz (Ice Lake) with 256G memory
parameters:
nr_threads: 50%
iterations: 4
mode: threads
ipc: pipe
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/202511281428.bfcbd5a8-lkp@intel.com
Details are as below:
-------------------------------------------------------------------------------------------------->
The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20251128/202511281428.bfcbd5a8-lkp@intel.com
=========================================================================================
compiler/cpufreq_governor/ipc/iterations/kconfig/mode/nr_threads/rootfs/tbox_group/testcase:
gcc-14/performance/pipe/4/x86_64-rhel-9.4/threads/50%/debian-13-x86_64-20250902.cgz/lkp-icl-2sp7/hackbench
commit:
e837456fdc ("sched/fair: Reimplement NEXT_BUDDY to align with EEVDF goals")
d206fbad93 ("sched/fair: Revert max_newidle_lb_cost bump")
e837456fdca81899 d206fbad9328ddb68ebabd7cf74
---------------- ---------------------------
%stddev %change %stddev
\ | \
2.603e+08 ± 6% -33.6% 1.73e+08 ± 4% cpuidle..time
5881942 ± 3% -62.9% 2180816 ± 13% cpuidle..usage
97892 ± 5% +17.9% 115437 ± 2% perf-c2c.HITM.local
98482 ± 5% +17.6% 115850 ± 2% perf-c2c.HITM.total
3.99 ± 8% -1.4 2.62 ± 3% mpstat.cpu.all.idle%
0.71 ± 2% -0.1 0.64 ± 2% mpstat.cpu.all.irq%
0.05 -0.0 0.03 ± 2% mpstat.cpu.all.soft%
1305956 ± 8% +19.7% 1562588 ± 11% numa-meminfo.node1.Active
1305948 ± 8% +19.7% 1562580 ± 11% numa-meminfo.node1.Active(anon)
863383 +20.4% 1039636 ± 11% numa-meminfo.node1.Shmem
326485 ± 8% +19.7% 390946 ± 10% numa-vmstat.node1.nr_active_anon
215818 +20.6% 260214 ± 11% numa-vmstat.node1.nr_shmem
326485 ± 8% +19.7% 390945 ± 10% numa-vmstat.node1.nr_zone_active_anon
1631510 +10.4% 1801907 ± 6% meminfo.Active
1631494 +10.4% 1801890 ± 6% meminfo.Active(anon)
1772671 +9.5% 1940770 ± 5% meminfo.Committed_AS
909474 +19.7% 1088760 ± 10% meminfo.Shmem
5.36 ±107% -3.2 2.11 ±223% perf-profile.calltrace.cycles-pp.process_simple.reader__read_event.perf_session__process_events.record__finish_output.cmd_record
6.59 ±100% -2.2 4.41 ±141% perf-profile.calltrace.cycles-pp.__ordered_events__flush.perf_session__process_user_event.reader__read_event.perf_session__process_events.record__finish_output
6.59 ±100% -2.2 4.41 ±141% perf-profile.calltrace.cycles-pp.perf_session__process_user_event.reader__read_event.perf_session__process_events.record__finish_output.cmd_record
5.36 ±107% -3.2 2.11 ±223% perf-profile.children.cycles-pp.process_simple
0.34 ± 4% -0.2 0.11 ± 14% turbostat.C1%
1.10 -0.8 0.28 ± 16% turbostat.C1E%
2.96 ± 8% -0.6 2.38 ± 2% turbostat.C6%
1.25 ± 5% -15.5% 1.05 ± 4% turbostat.CPU%c1
795.01 ± 4% -10.1% 714.37 ± 2% sched_debug.cfs_rq:/.util_est.avg
4969 ± 9% +122.0% 11030 ± 47% sched_debug.cpu.avg_idle.min
1716 ±141% +111.4% 3628 ± 61% sched_debug.cpu.curr->pid.min
1063335 ± 3% -47.4% 559053 ± 23% sched_debug.cpu.max_idle_balance_cost.avg
712039 ± 2% -29.8% 500000 sched_debug.cpu.max_idle_balance_cost.min
407716 +10.5% 450503 ± 6% proc-vmstat.nr_active_anon
1139851 +3.9% 1184811 ± 2% proc-vmstat.nr_file_pages
33054 +0.8% 33323 proc-vmstat.nr_kernel_stack
88427 ± 2% +6.0% 93718 ± 2% proc-vmstat.nr_mapped
227232 +19.8% 272194 ± 10% proc-vmstat.nr_shmem
407716 +10.5% 450503 ± 6% proc-vmstat.nr_zone_active_anon
44509495 -2.8% 43284126 proc-vmstat.numa_hit
44442837 -2.8% 43217032 proc-vmstat.numa_local
44571379 -2.7% 43348289 proc-vmstat.pgalloc_normal
43993792 -2.9% 42727500 proc-vmstat.pgfree
342580 -6.5% 320227 hackbench.throughput
334468 -6.2% 313595 hackbench.throughput_avg
342580 -6.5% 320227 hackbench.throughput_best
319665 -6.4% 299259 hackbench.throughput_worst
90.24 +6.6% 96.22 hackbench.time.elapsed_time
90.24 +6.6% 96.22 hackbench.time.elapsed_time.max
1.47e+08 +10.0% 1.617e+08 hackbench.time.involuntary_context_switches
37736 ± 3% +8.1% 40787 hackbench.time.minor_page_faults
6097 +1.8% 6206 hackbench.time.percent_of_cpu_this_job_got
5041 +9.1% 5501 hackbench.time.system_time
461.18 +2.2% 471.26 hackbench.time.user_time
4.238e+08 +4.5% 4.429e+08 hackbench.time.voluntary_context_switches
2.525e+10 -4.4% 2.415e+10 perf-stat.i.branch-instructions
5.10 -0.6 4.55 ± 4% perf-stat.i.cache-miss-rate%
3.459e+08 +12.9% 3.906e+08 perf-stat.i.cache-references
1.83 +5.5% 1.93 perf-stat.i.cpi
1.92e+11 +1.3% 1.946e+11 perf-stat.i.cpu-cycles
423018 +19.6% 506120 perf-stat.i.cpu-migrations
1.074e+11 -4.1% 1.03e+11 perf-stat.i.instructions
0.56 -5.4% 0.53 perf-stat.i.ipc
4.79 ± 2% -0.7 4.14 ± 5% perf-stat.overall.cache-miss-rate%
1.79 +5.7% 1.89 perf-stat.overall.cpi
0.56 -5.4% 0.53 perf-stat.overall.ipc
2.499e+10 -4.3% 2.392e+10 perf-stat.ps.branch-instructions
3.42e+08 +13.0% 3.865e+08 perf-stat.ps.cache-references
1.9e+11 +1.4% 1.926e+11 perf-stat.ps.cpu-cycles
417843 +19.8% 500456 perf-stat.ps.cpu-migrations
1.063e+11 -4.1% 1.02e+11 perf-stat.ps.instructions
9.709e+12 +2.4% 9.941e+12 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
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