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<body><span class="vcard"><a class="email" href="mailto:chris@chris-wilson.co.uk" title="Chris Wilson <chris@chris-wilson.co.uk>"> <span class="fn">Chris Wilson</span></a>
</span> changed
<a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [SNB+] clflush before pageflip causes jitter"
href="https://bugs.freedesktop.org/show_bug.cgi?id=57937">bug 57937</a>
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<th>What</th>
<th>Removed</th>
<th>Added</th>
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<td style="text-align:right;">Assignee</td>
<td>chris@chris-wilson.co.uk
</td>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
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<td style="text-align:right;">Summary</td>
<td>i915 SNA choppy graphics
</td>
<td>[SNB+] clflush before pageflip causes jitter
</td>
</tr>
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<td style="text-align:right;">Product</td>
<td>xorg
</td>
<td>DRI
</td>
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<td style="text-align:right;">Version</td>
<td>7.7 (2011)
</td>
<td>unspecified
</td>
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<td style="text-align:right;">Component</td>
<td>Driver/intel
</td>
<td>DRM/Intel
</td>
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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [SNB+] clflush before pageflip causes jitter"
href="https://bugs.freedesktop.org/show_bug.cgi?id=57937#c1">Comment # 1</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [SNB+] clflush before pageflip causes jitter"
href="https://bugs.freedesktop.org/show_bug.cgi?id=57937">bug 57937</a>
from <span class="vcard"><a class="email" href="mailto:chris@chris-wilson.co.uk" title="Chris Wilson <chris@chris-wilson.co.uk>"> <span class="fn">Chris Wilson</span></a>
</span></b>
<pre>Try a more recent kernel. The issue is that you do not have a working
set-caching ioctl and you end up polluting the bo cache with uncached buffers,
which are comparatively slow and in the worst case cause render corruption.
'sudo perf top' should say that most of your cpu overhead is spent clflushing
buffers as they expire, or worse that the clflush occurs just before the
pageflip.</pre>
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