Re: [linus:master] [mm, pcp] 6ccdcb6d3a: stress-ng.judy.ops_per_sec -4.7% regression

["Huang, Ying" <ying.huang@intel.com>]

Hi,

Thanks for test!

kernel test robot <oliver.sang@intel.com> writes:

> Hello,
>
> kernel test robot noticed a -4.7% regression of stress-ng.judy.ops_per_sec on:
>
>
> commit: 6ccdcb6d3a741c4e005ca6ffd4a62ddf8b5bead3 ("mm, pcp: reduce detecting time of consecutive high order page freeing")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
>
> testcase: stress-ng
> test machine: 224 threads 2 sockets Intel(R) Xeon(R) Platinum 8480CTDX (Sapphire Rapids) with 512G memory
> parameters:
>
> 	nr_threads: 100%
> 	testtime: 60s
> 	class: cpu-cache
> 	test: judy
> 	disk: 1SSD
> 	cpufreq_governor: performance
>
>
> In addition to that, the commit also has significant impact on the following tests:
>
> +------------------+-------------------------------------------------------------------------------------------------+
> | testcase: change | lmbench3: lmbench3.TCP.socket.bandwidth.10MB.MB/sec 23.7% improvement                           |
> | test machine     | 48 threads 2 sockets Intel(R) Xeon(R) CPU E5-2697 v2 @ 2.70GHz (Ivy Bridge-EP) with 112G memory |
> | test parameters  | cpufreq_governor=performance                                                                    |
> |                  | mode=development                                                                                |
> |                  | nr_threads=100%                                                                                 |
> |                  | test=TCP                                                                                        |
> |                  | test_memory_size=50%                                                                            |
> +------------------+-------------------------------------------------------------------------------------------------+
> | testcase: change | stress-ng: stress-ng.file-ioctl.ops_per_sec -6.6% regression                                    |
> | test machine     | 36 threads 1 sockets Intel(R) Core(TM) i9-9980XE CPU @ 3.00GHz (Skylake) with 32G memory        |
> | test parameters  | class=filesystem                                                                                |
> |                  | cpufreq_governor=performance                                                                    |
> |                  | disk=1SSD                                                                                       |
> |                  | fs=btrfs                                                                                        |
> |                  | nr_threads=10%                                                                                  |
> |                  | test=file-ioctl                                                                                 |
> |                  | testtime=60s                                                                                    |
> +------------------+-------------------------------------------------------------------------------------------------+

It's expected that this commit will benefit some workload (mainly
network, inter-process communication related) and hurt some workload.
But the  whole series should have no much regression.  Can you try the
whole series for the regression test cases?  The series start from
commit ca71fe1ad922 ("mm, pcp: avoid to drain PCP when process exit") to
commit 6ccdcb6d3a74 ("mm, pcp: reduce detecting time of consecutive high
order page freeing").

--
Best Regards,
Huang, Ying