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<b><a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO - CPU iowait higher when run the GPU multi decoding threads"
href="https://bugs.freedesktop.org/show_bug.cgi?id=109830#c32">Comment # 32</a>
on <a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO - CPU iowait higher when run the GPU multi decoding threads"
href="https://bugs.freedesktop.org/show_bug.cgi?id=109830">bug 109830</a>
from <span class="vcard"><a class="email" href="mailto:tvrtko.ursulin@linux.intel.com" title="Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>"> <span class="fn">Tvrtko Ursulin</span></a>
</span></b>
<pre>(In reply to Owen Zhang from <a href="show_bug.cgi?id=109830#c31">comment #31</a>)
<span class="quote">> (In reply to Tvrtko Ursulin from <a href="show_bug.cgi?id=109830#c30">comment #30</a>)
> > (In reply to Owen Zhang from <a href="show_bug.cgi?id=109830#c27">comment #27</a>)
> > > Hi,
> > >
> > > i have made the following changes on kernel 4.19:
> > >
> > > 1) apply the following patch:
> > > <a href="https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/">https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/</a>
> > > ?h=linux-4.20.y&id=0a2fff2428f1e175932dc3cf115b68c868e3a839
> >
> > This patch makes a difference on it's own? How much?
> >
> > If it does, I think you have to test by ensuring input data is cached before
> > the timing run, and dump the output to /dev/null.
> >
> > Otherwise you are accounting for the changes in kernel's block and
> > filesystem subsystems as well.
> >
> > P.S. I haven't had the time yet to try the repro using the latest
> > instructions.
>
> only apply this patch, there hasn't any difference. it also need to change
> the io_schedule_timeout to schedule_timeout.
>
> both apply these two changes, the cpu iowait number will be down.</span >
So only two changes in conjunction work? Test system is using device mapper?
Can you try pre-caching, a different block device and output to /dev/null?
(Without either patch applied.)</pre>
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