Greeting,
FYI, we noticed a -14.1% regression of phoronix-test-suite.stress-ng.SystemVMessagePassing.bogo_ops_s due to commit:
commit: 2a0abc59699896f03bf6f16efb8a3a490511216f ("x86, sched: Add support for frequency invariance on SKYLAKE_X")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
in testcase: phoronix-test-suite
on test machine: 96 threads Intel(R) Xeon(R) Gold 6252 CPU @ 2.10GHz with 192G memory
with following parameters:
test: stress-ng-1.2.2
option_a: System V Message Passing
cpufreq_governor: performance
ucode: 0x5002f01
test-description: The Phoronix Test Suite is the most comprehensive testing and benchmarking platform available that provides an extensible framework for which new tests can be easily added.
test-url: http://www.phoronix-test-suite.com/
If you fix the issue, kindly add following tag
Reported-by: kernel test robot <[email protected]>
Details are as below:
-------------------------------------------------------------------------------------------------->
To reproduce:
git clone https://github.com/intel/lkp-tests.git
cd lkp-tests
bin/lkp install job.yaml # job file is attached in this email
bin/lkp run job.yaml
=========================================================================================
compiler/cpufreq_governor/kconfig/option_a/rootfs/tbox_group/test/testcase/ucode:
gcc-9/performance/x86_64-rhel-8.3/System V Message Passing/debian-x86_64-phoronix/lkp-csl-2sp8/stress-ng-1.2.2/phoronix-test-suite/0x5002f01
commit:
1567c3e346 ("x86, sched: Add support for frequency invariance")
2a0abc5969 ("x86, sched: Add support for frequency invariance on SKYLAKE_X")
1567c3e3467cddeb 2a0abc59699896f03bf6f16efb8
---------------- ---------------------------
%stddev %change %stddev
\ | \
6736877 ? 2% -14.1% 5784719 phoronix-test-suite.stress-ng.SystemVMessagePassing.bogo_ops_s
2.509e+08 ? 82% -73.9% 65398195 ? 4% phoronix-test-suite.time.involuntary_context_switches
222.84 ? 78% -52.7% 105.51 ? 2% phoronix-test-suite.time.user_time
2.576e+08 ? 82% -73.3% 68843409 ? 4% phoronix-test-suite.time.voluntary_context_switches
phoronix-test-suite.stress-ng.SystemVMessagePassing.bogo_ops_s
7.2e+06 +-----------------------------------------------------------------+
7e+06 |-+ + .+.+ |
| + : + .+. : .+ + |
6.8e+06 |.. + : +..+ : +. : : |
6.6e+06 |-+ +.. : : +.. .+.. + : : |
| +.+ : .. + + : : |
6.4e+06 |-+ +.+ : : |
6.2e+06 |-+ : : |
6e+06 |-+ O O :: |
| O O O O O : O |
5.8e+06 |-+ O O O O O O + O O O O O |
5.6e+06 |-+ O O O O |
| |
5.4e+06 |-+ O |
5.2e+06 +-----------------------------------------------------------------+
[*] bisect-good sample
[O] bisect-bad sample
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.
Thanks,
Oliver Sang
On Mon, 2020-11-16 at 15:07 +0800, kernel test robot wrote:
> Greeting,
>
> FYI, we noticed a -14.1% regression of phoronix-test-suite.stress-ng.SystemVMessagePassing.bogo_ops_s due to commit:
>
>
> commit: 2a0abc59699896f03bf6f16efb8a3a490511216f ("x86, sched: Add support for frequency invariance on SKYLAKE_X")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
>
>
> in testcase: phoronix-test-suite
> on test machine: 96 threads Intel(R) Xeon(R) Gold 6252 CPU @ 2.10GHz with 192G memory
> with following parameters:
>
> test: stress-ng-1.2.2
> option_a: System V Message Passing
> cpufreq_governor: performance
> ucode: 0x5002f01
I haven't checked this regression yet, but when a "schedutil" change like
this patch triggers a regression when the "performance" governor is used,
the trouble might come in some roundabout way, eg. from cache alignment issues.
The patch defines a number of (not necessarily aligned) per-cpu variables, and
there was a recent thread where Boris Petkov, Tony Luck and Mel Gorman debugged
something that had similar characteristics:
"RE: [LKP] Re: [x86/mce] 1de08dccd3: will-it-scale.per_process_ops -14.1% regression"
https://lore.kernel.org/lkml/[email protected]/
I'll study this problem with that in mind.
Giovanni