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Re: Fio regression caused by f9fc8932b11f3bcf2a2626f567cb6fdd36a33a94
From: |
Paolo Bonzini |
Subject: |
Re: Fio regression caused by f9fc8932b11f3bcf2a2626f567cb6fdd36a33a94 |
Date: |
Fri, 6 May 2022 13:30:43 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 |
On 5/6/22 06:30, Lukáš Doktor wrote:
Hello all,
thank you for the responses, I ran 3 runs per each commit using 5 iteration of
fio-nbd using
f9fc8932b11f3bcf2a2626f567cb6fdd36a33a94
f9fc8932b11f3bcf2a2626f567cb6fdd36a33a94 + Stefan's commit
d7482ffe9756919531307330fd1c6dbec66e8c32
Ok, there's another simple change that can be made to bring performance
back to 6.2 levels, actually a bit better. I'll post patches soon.
Here are 4 fio runs:
6.2:
iops : min=58051, max=62260, avg=60282.57, stdev=1081.18, samples=30
clat percentiles (usec): 1.00th=[ 490], 99.99th=[ 775]
iops : min=59401, max=61290, avg=60651.27, stdev=468.24, samples=30
clat percentiles (usec): 1.00th=[ 490], 99.99th=[ 717]
iops : min=59583, max=60816, avg=60353.43, stdev=282.69, samples=30
clat percentiles (usec): 1.00th=[ 490], 99.99th=[ 701]
iops : min=58099, max=60713, avg=59739.53, stdev=755.49, samples=30
clat percentiles (usec): 1.00th=[ 494], 99.99th=[ 717]
patched:
iops : min=60616, max=62522, avg=61654.37, stdev=555.67, samples=30
clat percentiles (usec): 1.00th=[ 474], 99.99th=[ 1303]
iops : min=61841, max=63600, avg=62878.47, stdev=442.40, samples=30
clat percentiles (usec): 1.00th=[ 465], 99.99th=[ 685]
iops : min=62976, max=63910, avg=63531.60, stdev=261.05, samples=30
clat percentiles (usec): 1.00th=[ 461], 99.99th=[ 693]
iops : min=60803, max=63623, avg=62653.37, stdev=808.76, samples=30
clat percentiles (usec): 1.00th=[ 465], 99.99th=[ 685]
I also played a bit with direct wakeup of threads using a QemuEvent per thread.
Peak performance is higher (low percentiles are better) but the problem is that
it doesn't necessarily pick the most effective thread for wakeup resulting in
oscillations:
iops : min=60971, max=65726, avg=63771.93, stdev=1381.06, samples=30
clat percentiles (usec): 1.00th=[ 457], 99.99th=[ 685]
iops : min=57537, max=64914, avg=63694.37, stdev=1809.40, samples=30
clat percentiles (usec): 1.00th=[ 461], 99.99th=[ 693]
iops : min=58175, max=64711, avg=61277.80, stdev=2216.05, samples=30
clat percentiles (usec): 1.00th=[ 465], 99.99th=[ 685]
iops : min=56349, max=63938, avg=58442.33, stdev=2012.54, samples=30
clat percentiles (usec): 1.00th=[ 469], 99.99th=[ 668]
I'll go for the simple one.
Paolo