<html>
<head>
<base href="https://bugs.freedesktop.org/">
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - >2% perf drop in GfxBench T-Rex with "i965: disable loop unrolling in GLSL IR""
href="https://bugs.freedesktop.org/show_bug.cgi?id=99221">99221</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>>2% perf drop in GfxBench T-Rex with "i965: disable loop unrolling in GLSL IR"
</td>
</tr>
<tr>
<th>Product</th>
<td>Mesa
</td>
</tr>
<tr>
<th>Version</th>
<td>git
</td>
</tr>
<tr>
<th>Hardware</th>
<td>Other
</td>
</tr>
<tr>
<th>OS</th>
<td>All
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>medium
</td>
</tr>
<tr>
<th>Component</th>
<td>Drivers/DRI/i965
</td>
</tr>
<tr>
<th>Assignee</th>
<td>intel-3d-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>eero.t.tamminen@intel.com
</td>
</tr>
<tr>
<th>QA Contact</th>
<td>intel-3d-bugs@lists.freedesktop.org
</td>
</tr></table>
<p>
<div>
<pre>Patch series culminating in this commit changed performance in several tests:
-------------------------------------------------------
commit 40e9f2f13847ddd94e1216088aa00456d7b02d2b
Author: Timothy Arceri <<a href="mailto:timothy.arceri@collabora.com">timothy.arceri@collabora.com</a>>
AuthorDate: Tue Dec 13 11:37:25 2016 +1100
Commit: Timothy Arceri <<a href="mailto:timothy.arceri@collabora.com">timothy.arceri@collabora.com</a>>
CommitDate: Fri Dec 23 10:15:36 2016 +1100
i965: disable loop unrolling in GLSL IR
There is a single regression in loop unrolling which is:
loops HURT: shaders/orbital_explorer.shader_test GS SIMD8: 0 -> 1
However the loop is huge so it seems reasonable not to unroll it. It's
surprising that GLSL IR does unroll it.
-------------------------------------------------------
On SKL i5-6600K (GT2), the changes were following (in FullHD size):
Performance dropped due to "disable loop unrolling in GLSL IR":
- 2.7% SynMark PSPom
- 2.3% SynMark PSPhong
- 2.2% GfxBench T-Rex (GL version)
- 0.5% SynMark PSBump8
Performance increased due to "use nir loop unrolling pass":
+ 12.5% SynMark ShMapPcf
+ 3.9% SynMark CSDof (+8.4% from "use nir_lower_indirect_derefs() for GLSL")
+ 2.2% SynMark DevRes (composite test including other affected tests)
+ 0.5% Unigine Valley
+ 0.5% SynMark PSBump2
Results are similar on other platforms, except for CSDof where results depend a
lot on the HW. GfxBench is v4.0, SynMark v7.0.
CSDof performance increased a lot on SKL GT2, KBL GT2 and a bit BYT, but its
perf dropped a lot SKL GT3e & GT4e, BDW GT3 & GT2, BSW, and a bit on HSW GT3e
and BXT.
After these 2 changes, SynMark shader compilation speed test is ~25% faster on
all platforms which is pretty good.</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are the QA Contact for the bug.</li>
<li>You are the assignee for the bug.</li>
</ul>
</body>
</html>