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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [GEN9] 20% perf drop in windowed/composited GpuTest Triangle"
href="https://bugs.freedesktop.org/show_bug.cgi?id=108598">108598</a>
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<th>Summary</th>
<td>[GEN9] 20% perf drop in windowed/composited GpuTest Triangle
</td>
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<th>Product</th>
<td>DRI
</td>
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<th>Version</th>
<td>DRI git
</td>
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<th>Hardware</th>
<td>Other
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>minor
</td>
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<th>Priority</th>
<td>medium
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<th>Component</th>
<td>DRM/Intel
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<th>Assignee</th>
<td>intel-gfx-bugs@lists.freedesktop.org
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<th>Reporter</th>
<td>eero.t.tamminen@intel.com
</td>
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<th>QA Contact</th>
<td>intel-gfx-bugs@lists.freedesktop.org
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<th>CC</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
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<th>i915 platform</th>
<td>BXT, CFL, KBL, SKL
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<pre>HW setup:
* GEN9 HW (BXT, SKL, KBL...)
* Full HD monitor
SW setups:
* Ubuntu 18.04 with Unity desktop (= compiz compositor)
* Git versions of drm-tip kernel, X server and Mesa, so that modifiers work
with X
* Modifier support enabled in X server (i.e. Mesa can use end-to-end render
buffer compression):
----------------------
Section "ServerFlags"
Option "Debug" "dmabuf_capable"
EndSection
----------------------
* Monitor native Full HD resolution
Between following drm-tip commits/dates:
a3d29ccd2c: drm-tip: 2018y-09m-30d-06h-55m-08s UTC integration manifest
26e7a7d954: drm-tip: 2018y-10m-02d-12h-38m-20s UTC integration manifest
There were following performance regressions:
* 20% in GpuTest v0.7 Triangle windowed (1366x768, composited)
* 1-2% SynMark v7 OglCSCloth, OglBatch1-3 (all fullscreen)
* 1% SynMark v7 OglGeom*, GpuTest v0.7 Triangle fullscreen
SynMark use-cases have all about 2M of vertices with pass-through shaders, so
at FullHD they're memory bandwidth limited. All the tests have high FPS,
especially the trivial triangle tests.
Interestingly, higher FPS windowed Triangle case perf drop is much higher than
the fullscreen Triangle one, so very high FPS can be one trigger for this.
Above regression percentages are from SKL i5 GT2, where the regressions are
most visible. Regressions are visible on all of our GEN9 platforms, but
smaller on some of them.
On SKL GT2, in the windowed Triangle case:
* memory and GPU power usage decreased
* CPU power usage increased
So that in total ~4% more power is used in this case (according to RAPL).
SKL GT2 isn't TDP limited, so CPU side just using more power doesn't explain
the drop.
Median power usage in our full benchmarks test set didn't change, regressions
in all the other tests, than the very high FPS windowed Triangle one, are so
small that they can't be bisected, and the trivial windowed Triangle case isn't
that interesting use-case.
-> WONTFIX sounds fine as long as somebody checks what commit caused the perf
drop.
(I'm not myself looking at GFX perf anymore, filing this was the last remaining
item.)</pre>
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