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

Damien Le Moal
2022-08-12T15:42:56Z

On 2022/08/12 4:13, John Garry wrote:
> On 12/08/2022 06:01, Oliver Sang wrote:
>> hi, Damien Le Moal,
>>
>> On Tue, Aug 09, 2022 at 07:55:53AM -0700, Damien Le Moal wrote:
>>> 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.
>>
>> we noticed the commit is already in mainline now, and in our tests, there is
>> still similar regression and also on other platforms.
>> could you guide us how to check "which host driver is being used for this
>> test"? hope to supply some useful information.
>>
>
> For me, a complete kernel log may help.

I had a look yesterday with my test rig. I did not see any difference in the
default max_sectors_kb values for various drives between 5.18 and 5.19 (current
linus tree). The test machine has 2 AHCI adapters: Intel and Marvell. Both use
the regular AHCI driver. I have another rig with different ATA adapters but it
is powered down and I am traveling... So cannot test that right now.

>
>>>
>>>>
>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> If you fix the issue, kindly add following tag
>>>>>> Reported-by: kernel test robot <oliver.sang@intel.com>
>>>>>>
>>>>>>
>>>>>> 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
>> .
>

--
Damien Le Moal
Western Digital Research