Re: [LKP] Re: [blk] 8c5035dfbb: fio.read_iops -10.6% regression
From: Yin Fengwei
Date: Sun Oct 09 2022 - 01:47:48 EST
Hi Kuai,
On 10/8/22 16:00, Yu Kuai wrote:
> Hi,
>
> 在 2022/10/08 10:50, kernel test robot 写道:
>> Greeting,
>>
>> FYI, we noticed a -10.6% regression of fio.read_iops due to commit:
>
> I don't know how this is working but I'm *sure* this commit won't affect
> performance. Please take a look at the commit, only wbt initialization
> is touched, which is done while creating the device:
>
> device_add_disk
> blk_register_queue
> wbt_enable_default
> wbt_init
>
> And io path is the same with or without this commit.
>
> By the way, wbt should only work for write.
Some information here:
It looks like the line
wbt_set_write_cache(q, test_bit(QUEUE_FLAG_WC, &q->queue_flags));
matters.
If move only this line to original position based on 8c5035dfbb,
the regression is gone.
If move only this line before ret = rq_qos_add() (just like your patch
did, but only with this line) based on 8c5035dfbb, the regression can
be reproduced.
Regards
Yin, Fengwei
>
> Thanks,
> Kuai
>>
>> commit: 8c5035dfbb9475b67c82b3fdb7351236525bf52b ("blk-wbt: call rq_qos_add() after wb_normal is initialized")
>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
>>
>> in testcase: fio-basic
>> on test machine: 192 threads 4 sockets Intel(R) Xeon(R) Platinum 9242 CPU @ 2.30GHz (Cascade Lake) with 192G memory
>> with following parameters:
>>
>> runtime: 300s
>> nr_task: 8t
>> disk: 1SSD
>> fs: btrfs
>> rw: randread
>> bs: 2M
>> ioengine: sync
>> test_size: 256g
>> cpufreq_governor: performance
>>
>> test-description: Fio is a tool that will spawn a number of threads or processes doing a particular type of I/O action as specified by the user.
>> test-url: https://github.com/axboe/fio
>>
>>
>> Details are as below:
>>
>> =========================================================================================
>> bs/compiler/cpufreq_governor/disk/fs/ioengine/kconfig/nr_task/rootfs/runtime/rw/tbox_group/test_size/testcase:
>> 2M/gcc-11/performance/1SSD/btrfs/sync/x86_64-rhel-8.3/8t/debian-11.1-x86_64-20220510.cgz/300s/randread/lkp-csl-2ap4/256g/fio-basic
>>
>> commit:
>> f7de4886fe ("rnbd-srv: remove struct rnbd_dev")
>> 8c5035dfbb ("blk-wbt: call rq_qos_add() after wb_normal is initialized")
>>
>> f7de4886fe8f008a 8c5035dfbb9475b67c82b3fdb73
>> ---------------- ---------------------------
>> %stddev %change %stddev
>> \ | \
>> 0.03 ±106% +0.2 0.22 ± 80% fio.latency_20ms%
>> 0.02 ± 33% -0.0 0.01 ± 12% fio.latency_4ms%
>> 2508 -10.6% 2243 fio.read_bw_MBps
>> 6717440 +17.6% 7897088 fio.read_clat_90%_us
>> 6892202 +19.0% 8202922 fio.read_clat_95%_us
>> 7602176 ± 4% +18.4% 9000277 ± 3% fio.read_clat_99%_us
>> 6374238 +11.8% 7127450 fio.read_clat_mean_us
>> 363825 ± 10% +74.9% 636378 ± 5% fio.read_clat_stddev
>> 1254 -10.6% 1121 fio.read_iops
>> 104.97 +11.8% 117.32 fio.time.elapsed_time
>> 104.97 +11.8% 117.32 fio.time.elapsed_time.max
>> 13731 +5.6% 14498 ± 4% fio.time.maximum_resident_set_size
>> 116.00 -8.2% 106.50 fio.time.percent_of_cpu_this_job_got
>> 1.998e+10 +11.4% 2.226e+10 cpuidle..time
>> 3.27 ± 3% +4.6% 3.42 iostat.cpu.iowait
>> 4.49 ± 68% -2.1 2.38 ±152% perf-profile.children.cycles-pp.number
>> 4.49 ± 68% -2.5 1.98 ±175% perf-profile.self.cycles-pp.number
>> 557763 +5.4% 587781 proc-vmstat.pgfault
>> 25488 +3.1% 26274 proc-vmstat.pgreuse
>> 2459048 -10.1% 2209482 vmstat.io.bi
>> 184649 ± 5% -10.4% 165526 ± 7% vmstat.system.cs
>> 111733 ± 30% +61.8% 180770 ± 21% numa-meminfo.node0.AnonPages
>> 113221 ± 30% +60.2% 181416 ± 21% numa-meminfo.node0.Inactive(anon)
>> 11301 ± 24% +164.5% 29888 ±117% numa-meminfo.node2.Active(file)
>> 104911 ± 39% -80.5% 20456 ±100% numa-meminfo.node3.AnonHugePages
>> 131666 ± 27% -67.9% 42297 ± 82% numa-meminfo.node3.AnonPages
>> 132698 ± 26% -67.5% 43158 ± 81% numa-meminfo.node3.Inactive(anon)
>> 27934 ± 30% +61.8% 45196 ± 21% numa-vmstat.node0.nr_anon_pages
>> 28306 ± 30% +60.2% 45358 ± 21% numa-vmstat.node0.nr_inactive_anon
>> 28305 ± 30% +60.2% 45357 ± 21% numa-vmstat.node0.nr_zone_inactive_anon
>> 6291 ± 24% +68.0% 10567 ± 26% numa-vmstat.node2.workingset_nodes
>> 32925 ± 27% -67.9% 10571 ± 82% numa-vmstat.node3.nr_anon_pages
>> 33182 ± 26% -67.5% 10786 ± 81% numa-vmstat.node3.nr_inactive_anon
>> 33182 ± 26% -67.5% 10786 ± 81% numa-vmstat.node3.nr_zone_inactive_anon
>> 161.78 ± 4% -28.2% 116.10 ± 30% sched_debug.cfs_rq:/.runnable_avg.avg
>> 161.46 ± 4% -28.2% 115.85 ± 30% sched_debug.cfs_rq:/.util_avg.avg
>> 426382 +11.0% 473345 ± 6% sched_debug.cpu.clock.avg
>> 426394 +11.0% 473357 ± 6% sched_debug.cpu.clock.max
>> 426370 +11.0% 473331 ± 6% sched_debug.cpu.clock.min
>> 426139 +10.9% 472586 ± 6% sched_debug.cpu.clock_task.avg
>> 426368 +11.0% 473130 ± 6% sched_debug.cpu.clock_task.max
>> 416196 +11.1% 462228 ± 6% sched_debug.cpu.clock_task.min
>> 1156 ± 7% -10.8% 1031 ± 6% sched_debug.cpu.curr->pid.stddev
>> 426372 +11.0% 473334 ± 6% sched_debug.cpu_clk
>> 425355 +11.0% 472318 ± 6% sched_debug.ktime
>> 426826 +11.0% 473787 ± 6% sched_debug.sched_clk
>> 1.263e+09 -7.9% 1.164e+09 ± 3% perf-stat.i.branch-instructions
>> 190886 ± 5% -10.8% 170290 ± 7% perf-stat.i.context-switches
>> 1.979e+09 -8.8% 1.804e+09 ± 2% perf-stat.i.dTLB-loads
>> 8.998e+08 -8.2% 8.257e+08 ± 2% perf-stat.i.dTLB-stores
>> 6.455e+09 -8.0% 5.938e+09 ± 3% perf-stat.i.instructions
>> 21.78 -8.4% 19.95 perf-stat.i.metric.M/sec
>> 7045315 ± 4% -14.0% 6057863 ± 6% perf-stat.i.node-load-misses
>> 2658563 ± 7% -21.9% 2077647 ± 12% perf-stat.i.node-loads
>> 414822 ± 4% -12.9% 361455 ± 3% perf-stat.i.node-store-misses
>> 1.251e+09 -7.8% 1.154e+09 ± 3% perf-stat.ps.branch-instructions
>> 189082 ± 5% -10.7% 168849 ± 7% perf-stat.ps.context-switches
>> 1.96e+09 -8.8% 1.789e+09 ± 2% perf-stat.ps.dTLB-loads
>> 8.912e+08 -8.1% 8.187e+08 ± 2% perf-stat.ps.dTLB-stores
>> 6.393e+09 -7.9% 5.888e+09 ± 3% perf-stat.ps.instructions
>> 6978485 ± 4% -13.9% 6006510 ± 6% perf-stat.ps.node-load-misses
>> 2633627 ± 7% -21.8% 2060033 ± 12% perf-stat.ps.node-loads
>> 410822 ± 4% -12.8% 358289 ± 3% perf-stat.ps.node-store-misses
>>
>>
>> If you fix the issue, kindly add following tag
>> | Reported-by: kernel test robot <yujie.liu@xxxxxxxxx>
>> | Link: https://lore.kernel.org/r/202210081045.77ddf59b-yujie.liu@xxxxxxxxx
>>
>>
>> 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.
>>
>>
>> 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.
>>
>>
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