Re: [ata] 0568e61225: stress-ng.copy-file.ops_per_sec -15.0% regression

From: Damien Le Moal
Date: Tue Aug 09 2022 - 10:56:08 EST

On 2022/08/09 2:58, John Garry wrote:
> On 08/08/2022 15:52, Damien Le Moal wrote:
>> On 2022/08/05 1:05, kernel test robot wrote:
>>>
>>>
>>> Greeting,
>>>
>>> FYI, we noticed a -15.0% regression of stress-ng.copy-file.ops_per_sec due to commit:
>>>
>>>
>>> commit: 0568e6122574dcc1aded2979cd0245038efe22b6 ("ata: libata-scsi: cap ata_device->max_sectors according to shost->max_sectors")
>>> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
>>>
>>> in testcase: stress-ng
>>> on test machine: 96 threads 2 sockets Ice Lake with 256G memory
>>> with following parameters:
>>>
>>> nr_threads: 10%
>>> disk: 1HDD
>>> testtime: 60s
>>> fs: f2fs
>>> class: filesystem
>>> test: copy-file
>>> cpufreq_governor: performance
>>> ucode: 0xb000280
>>
>> Without knowing what the device adapter is, hard to say where the problem is. I
>> suspect that with the patch applied, we may be ending up with a small default
>> max_sectors value, causing overhead due to more commands than necessary.
>>
>> Will check what I see with my test rig.
>
> As far as I can see, this patch should not make a difference unless the
> ATA shost driver is setting the max_sectors value unnecessarily low.

That is my hunch too, hence my question about which host driver is being used
for this test... That is not apparent from the problem report.

>
>>
>>>
>>>
>>>
>>>
>>> If you fix the issue, kindly add following tag
>>> Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
>>>
>>>
>>> Details are as below:
>>> -------------------------------------------------------------------------------------------------->
>>>
>>>
>>> To reproduce:
>>>
>>> git clone https://github.com/intel/lkp-tests.git
>>> cd lkp-tests
>>> sudo bin/lkp install job.yaml # job file is attached in this email
>>> bin/lkp split-job --compatible job.yaml # generate the yaml file for lkp run
>>> sudo bin/lkp run generated-yaml-file
>>>
>>> # if come across any failure that blocks the test,
>>> # please remove ~/.lkp and /lkp dir to run from a clean state.
>>>
>>> =========================================================================================
>>> class/compiler/cpufreq_governor/disk/fs/kconfig/nr_threads/rootfs/tbox_group/test/testcase/testtime/ucode:
>>> filesystem/gcc-11/performance/1HDD/f2fs/x86_64-rhel-8.3/10%/debian-11.1-x86_64-20220510.cgz/lkp-icl-2sp1/copy-file/stress-ng/60s/0xb000280
>>>
>>> commit:
>>> 4cbfca5f77 ("scsi: scsi_transport_sas: cap shost opt_sectors according to DMA optimal limit")
>>> 0568e61225 ("ata: libata-scsi: cap ata_device->max_sectors according to shost->max_sectors")
>>>
>>> 4cbfca5f7750520f 0568e6122574dcc1aded2979cd0
>>> ---------------- ---------------------------
>>> %stddev %change %stddev
>>> \ | \
>>> 1627 -14.9% 1385 stress-ng.copy-file.ops
>>> 27.01 -15.0% 22.96 stress-ng.copy-file.ops_per_sec
>>> 8935079 -11.9% 7870629 stress-ng.time.file_system_outputs
>>> 14.88 ± 5% -31.8% 10.14 ± 3% stress-ng.time.percent_of_cpu_this_job_got
>>> 50912 -14.7% 43413 vmstat.io.bo
>>> 93.78 +1.4% 95.10 iostat.cpu.idle
>>> 3.89 -31.6% 2.66 iostat.cpu.iowait
>>> 4.01 -1.3 2.74 mpstat.cpu.all.iowait%
>>> 0.23 ± 9% -0.1 0.17 ± 11% mpstat.cpu.all.sys%
>>> 1.66 ± 37% -1.2 0.51 ± 55% perf-profile.calltrace.cycles-pp.f2fs_write_end.generic_perform_write.f2fs_buffered_write_iter.f2fs_file_write_iter.do_iter_readv_writev
>>> 1.66 ± 37% -1.1 0.59 ± 25% perf-profile.children.cycles-pp.f2fs_write_end
>>> 1.51 ± 40% -1.1 0.45 ± 26% perf-profile.children.cycles-pp.f2fs_dirty_data_folio
>>> 1.21 ± 49% -1.0 0.23 ± 33% perf-profile.children.cycles-pp.f2fs_update_dirty_folio
>>> 0.88 ± 56% -0.8 0.04 ±111% perf-profile.children.cycles-pp.native_queued_spin_lock_slowpath
>>> 0.14 ± 26% +0.1 0.25 ± 28% perf-profile.children.cycles-pp.page_cache_ra_unbounded
>>> 0.88 ± 56% -0.8 0.04 ±112% perf-profile.self.cycles-pp.native_queued_spin_lock_slowpath
>>> 3164876 ± 9% -20.2% 2524713 ± 7% perf-stat.i.cache-misses
>>> 4.087e+08 -4.6% 3.899e+08 perf-stat.i.dTLB-loads
>>> 313050 ± 10% -18.4% 255410 ± 6% perf-stat.i.node-loads
>>> 972573 ± 9% -16.4% 812873 ± 6% perf-stat.i.node-stores
>>> 3114748 ± 9% -20.2% 2484807 ± 7% perf-stat.ps.cache-misses
>>> 4.022e+08 -4.6% 3.837e+08 perf-stat.ps.dTLB-loads
>>> 308178 ± 10% -18.4% 251418 ± 6% perf-stat.ps.node-loads
>>> 956996 ± 9% -16.4% 799948 ± 6% perf-stat.ps.node-stores
>>> 358486 -8.3% 328694 proc-vmstat.nr_active_file
>>> 1121620 -11.9% 987816 proc-vmstat.nr_dirtied
>>> 179906 -6.7% 167912 proc-vmstat.nr_dirty
>>> 1151201 -1.7% 1131322 proc-vmstat.nr_file_pages
>>> 100181 +9.9% 110078 ± 2% proc-vmstat.nr_inactive_file
>>> 846362 -14.6% 722471 proc-vmstat.nr_written
>>> 358486 -8.3% 328694 proc-vmstat.nr_zone_active_file
>>> 100181 +9.9% 110078 ± 2% proc-vmstat.nr_zone_inactive_file
>>> 180668 -6.8% 168456 proc-vmstat.nr_zone_write_pending
>>> 556469 -3.5% 536985 proc-vmstat.pgactivate
>>> 3385454 -14.6% 2889953 proc-vmstat.pgpgout
>>>
>>>
>>>
>>>
>>> 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.
>>>
>>>
>>
>>
>


--
Damien Le Moal
Western Digital Research