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

From: John Garry
Date: Fri Aug 12 2022 - 07:14:53 EST

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.








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
.