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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Long pauses with Unreal demo Elemental on R9270X since : Always flush the HDP cache before submitting a CS to the GPU"
href="https://bugs.freedesktop.org/show_bug.cgi?id=84662">84662</a>
</td>
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<tr>
<th>Summary</th>
<td>Long pauses with Unreal demo Elemental on R9270X since : Always flush the HDP cache before submitting a CS to the GPU
</td>
</tr>
<tr>
<th>Product</th>
<td>Mesa
</td>
</tr>
<tr>
<th>Version</th>
<td>git
</td>
</tr>
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<th>Hardware</th>
<td>Other
</td>
</tr>
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<th>OS</th>
<td>All
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>medium
</td>
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<th>Component</th>
<td>Drivers/Gallium/radeonsi
</td>
</tr>
<tr>
<th>Assignee</th>
<td>dri-devel@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>adf.lists@gmail.com
</td>
</tr></table>
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<pre>R9270X PCIE 2.0 2 gig vram 4 gig ram.
Unreal demo Elemental only recently started working with git llvm/mesa, do no
bisection done on these.
The demo even when working is very broken - constant 1/4 sec stutters with a
couple of 1/2 - 1 sec.
But after -
commit 4439d469706699b4e69ef410ebc9115339f6e9e6
Author: Michel Dänzer <<a href="mailto:michel.daenzer@amd.com">michel.daenzer@amd.com</a>>
Date: Thu Jul 31 18:43:49 2014 +0900
drm/radeon: Always flush the HDP cache before submitting a CS to the GPU
This ensures the GPU sees all previous CPU writes to VRAM, which makes it
safe:
* For userspace to stream data from CPU to GPU via VRAM instead of GTT
* For IBs to be stored in VRAM instead of GTT
* For ring buffers to be stored in VRAM instead of GTT, if the HPD flush
is performed via MMIO
There are far longer pauses of many seconds - run time to unreal logo on "good"
is 3:45 on bad best 5:39 can be longer.
Screens to be attached show quite different vram/gtt usage between good and
bad.
Related to
<a class="bz_bug_link
bz_status_NEW "
title="NEW - R9270X pyrit benchmark perf regressions with latest kernel/llvm"
href="show_bug.cgi?id=82050">https://bugs.freedesktop.org/show_bug.cgi?id=82050</a>
I bisected to the same commit in that bug, but applying the mesa patch
<a class="bz_bug_link
bz_status_NEW "
title="NEW - R9270X pyrit benchmark perf regressions with latest kernel/llvm"
href="show_bug.cgi?id=82050#c19">https://bugs.freedesktop.org/show_bug.cgi?id=82050#c19</a>
doesn't help here.
CONFIG_CMA is not set.
Tried kernel org 3.17-rc7 as it was reported in above as working, but not for
me.</pre>
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