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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#c33">Comment # 33</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:owen.zhang@intel.com" title="Owen Zhang <owen.zhang@intel.com>"> <span class="fn">Owen Zhang</span></a>
</span></b>
<pre>(In reply to Tvrtko Ursulin from <a href="show_bug.cgi?id=109830#c32">comment #32</a>)
<span class="quote">> (In reply to Owen Zhang from <a href="show_bug.cgi?id=109830#c31">comment #31</a>)
> > (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.
>
> 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.)</span >
yes only two changes can work now, and we use device mapper.
now we used pre-allocate the buffer and no output in our test case.</pre>
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