<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 - Kernel code no longer counts EU correctly for i5-5250U (HD Graphics 6000 BroadWell U-Processor GT3)"
href="https://bugs.freedesktop.org/show_bug.cgi?id=108712">108712</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Kernel code no longer counts EU correctly for i5-5250U (HD Graphics 6000 BroadWell U-Processor GT3)
</td>
</tr>
<tr>
<th>Product</th>
<td>DRI
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>x86-64 (AMD64)
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux (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>DRM/Intel
</td>
</tr>
<tr>
<th>Assignee</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>gordon.lack@dsl.pipex.com
</td>
</tr>
<tr>
<th>QA Contact</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>CC</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=142439" name="attach_142439" title="Attached information files, as noted n Description/Comment.">attachment 142439</a> <a href="attachment.cgi?id=142439&action=edit" title="Attached information files, as noted n Description/Comment.">[details]</a></span>
Attached information files, as noted n Description/Comment.
The Ubuntu Bioinc kernels (4.15.x) report an i5-5250U processor (with HD
Graphics 6000 BroadWell U-Processor GT3 GPU) as having 48 EUs.
The Cosmic ones (4.18.x) report it has having only 24. This is a result of only
4 EUs per sub-slice being counted (it should have 8). Unsurprisingly this
result sin a significant loss of compute power when software uses this value to
determine how to run.
The code that determines how many EUs there are is in intel_device_info.c, and
this was changed in the 4.17 kernel series by this commit:
<a href="https://github.com/torvalds/linux/commit/8cc7669355136f8952779e6f60053c1284d59c4d">https://github.com/torvalds/linux/commit/8cc7669355136f8952779e6f60053c1284d59c4d</a>
I've attached the intel_reg dump info for the graphics set-up and also 4.15.x
and 4.18.x clinfo and the contents of the debug file-system
(/sys/kernel/debug/dri/0).
The clinfo output contains a debug statement added to the beignet code on the
system which reports what it gets from the register-reading kernel code, then
sets it to 48 regardless). This was originally reported as a beignet bug
(<a href="https://bugs.launchpad.net/ubuntu/+source/beignet/+bug/1800752">https://bugs.launchpad.net/ubuntu/+source/beignet/+bug/1800752</a>).
Attachment files are:
intel_reg_dump.txt
4.15.0-38-generic.clinfo
4.15.0-38-generic.dri-debug
4.18.0-10-generic.clinfo
4.18.0-10-generic.dri-debug</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are the assignee for the bug.</li>
<li>You are the QA Contact for the bug.</li>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>