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<base href="https://bugs.freedesktop.org/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Xorg take 100% CPU when using multiple independent screen configuration"
href="https://bugs.freedesktop.org/show_bug.cgi?id=90482">90482</a>
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<th>Summary</th>
<td>Xorg take 100% CPU when using multiple independent screen configuration
</td>
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<th>Product</th>
<td>xorg
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>x86-64 (AMD64)
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<th>OS</th>
<td>Linux (All)
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>medium
</td>
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<th>Component</th>
<td>Driver/nouveau
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<th>Assignee</th>
<td>nouveau@lists.freedesktop.org
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<th>Reporter</th>
<td>dura@duradsl.duckdns.org
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<th>QA Contact</th>
<td>xorg-team@lists.x.org
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=115835" name="attach_115835" title="my xorg.conf">attachment 115835</a> <a href="attachment.cgi?id=115835&action=edit" title="my xorg.conf">[details]</a></span>
my xorg.conf
My xorg setup is based on two independent screen (see attached xorg.conf). Most
of the time the Xorg process eat 100% of one CPU core.
I will try to explain what I think is the problem and the fix (or workaround) I
made to the nouveau code.
Basically, the problem is that nouveau add a socket to the xorg socket list but
does not register a handler that will be able to deal with it. When data is
received on this socket the Select call in xorg-server/os/WaitFor.c will return
but the data will not be read. When Select is called again it returns
immediately because data was not read, and again, and again, resulting in 100%
CPU core consumption.
Now, some details (based on xf86-video-nouveau-1.0.11 source code)
To add a socket in the xorg server list AddGeneralSocket is used.
In src/drmmode_display.c AddGeneralSocket is called in two places: line 1605
(via drmmode_uevent_init and line 1554) and 1610. If line 1608 condition is not
meet, a socket is added without an handler so drmmode_wakeup_handler will never
be called with correct data.
My solution is to add a new handler that will only handle the udev part when
line 1608 condition is not meet. See attached patch.</pre>
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