Messages in this thread | | | Subject | Re: [btrfs] 96bed17ad9: fio.write_iops -59.7% regression | From | Josef Bacik <> | Date | Wed, 4 Nov 2020 11:48:11 -0500 |
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On 11/4/20 1:16 AM, kernel test robot wrote: > Greeting, > > FYI, we noticed a -59.7% regression of fio.write_iops due to commit: > > > commit: 96bed17ad9d425ff6958a2e6f87179453a3d76f2 ("btrfs: simplify the logic in need_preemptive_flushing") > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master > > > in testcase: fio-basic > on test machine: 192 threads Intel(R) Xeon(R) CPU @ 2.20GHz with 192G memory > with following parameters: > > disk: 1SSD > fs: btrfs > runtime: 300s > nr_task: 8 > rw: write > bs: 4k > ioengine: sync > test_size: 256g > cpufreq_governor: performance > ucode: 0x4002f01 > > 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 >
I generally ignore these reports, but since it's FIO I figured at least the test itself was valid. However once again I'm unable to reproduce the results
linus master:
task_0: (groupid=0, jobs=8): err= 0: pid=38586: Wed Nov 4 08:13:36 2020 write: IOPS=168k, BW=655MiB/s (687MB/s)(192GiB/300001msec); 0 zone resets clat (usec): min=26, max=786, avg=47.15, stdev= 7.21 lat (usec): min=26, max=786, avg=47.21, stdev= 7.21 clat percentiles (nsec): | 1.00th=[31872], 5.00th=[35584], 10.00th=[37632], 20.00th=[40704], | 30.00th=[43264], 40.00th=[45312], 50.00th=[47360], 60.00th=[48896], | 70.00th=[50944], 80.00th=[52992], 90.00th=[56064], 95.00th=[59136], | 99.00th=[65280], 99.50th=[68096], 99.90th=[74240], 99.95th=[77312], | 99.99th=[88576] bw ( KiB/s): min=63752, max=112864, per=12.50%, avg=83810.53, stdev=3403.48, samples=4792 iops : min=15938, max=28216, avg=20952.61, stdev=850.87, samples=4792 lat (usec) : 50=65.73%, 100=34.27%, 250=0.01%, 500=0.01%, 750=0.01% lat (usec) : 1000=0.01% cpu : usr=2.22%, sys=97.77%, ctx=5054, majf=0, minf=63 IO depths : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0% submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% issued rwts: total=0,50298940,0,0 short=0,0,0,0 dropped=0,0,0,0 latency : target=0, window=0, percentile=100.00%, depth=32
Run status group 0 (all jobs): WRITE: bw=655MiB/s (687MB/s), 655MiB/s-655MiB/s (687MB/s-687MB/s), io=192GiB (206GB), run=300001-300001msec
kdave/for-next-20201104 task_0: (groupid=0, jobs=8): err= 0: pid=6652: Wed Nov 4 08:41:52 2020 write: IOPS=180k, BW=705MiB/s (739MB/s)(207GiB/300001msec); 0 zone resets clat (usec): min=17, max=10603, avg=43.91, stdev= 9.62 lat (usec): min=17, max=10603, avg=43.98, stdev= 9.62 clat percentiles (nsec): | 1.00th=[25984], 5.00th=[31104], 10.00th=[33536], 20.00th=[37120], | 30.00th=[39168], 40.00th=[41216], 50.00th=[43264], 60.00th=[45824], | 70.00th=[47872], 80.00th=[50944], 90.00th=[54528], 95.00th=[57600], | 99.00th=[64768], 99.50th=[68096], 99.90th=[74240], 99.95th=[78336], | 99.99th=[90624] bw ( KiB/s): min=66760, max=123160, per=12.50%, avg=90221.11, stdev=9052.52, samples=4792 iops : min=16690, max=30790, avg=22555.24, stdev=2263.14, samples=4792 lat (usec) : 20=0.01%, 50=77.24%, 100=22.75%, 250=0.01%, 500=0.01% lat (usec) : 750=0.01%, 1000=0.01% lat (msec) : 2=0.01%, 4=0.01%, 20=0.01% cpu : usr=1.67%, sys=98.31%, ctx=4806, majf=0, minf=68 IO depths : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0% submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% issued rwts: total=0,54134917,0,0 short=0,0,0,0 dropped=0,0,0,0 latency : target=0, window=0, percentile=100.00%, depth=32
Run status group 0 (all jobs): WRITE: bw=705MiB/s (739MB/s), 705MiB/s-705MiB/s (739MB/s-739MB/s), io=207GiB (222GB), run=300001-300001msec
So instead of -60% iops regression, I'm seeing a 7% iops improvement. The only difference is that my machine doesn't have 192 threads, it has 80. Thanks,
Josef
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