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* [Bug 90482] New: Xorg take 100% CPU when using multiple independent screen configuration
@ 2015-05-16 15:14 bugzilla-daemon-CC+yJ3UmIYqDUpFQwHEjaQ
       [not found] ` <bug-90482-8800-V0hAGp6uBxMKqLRl/0Ahz6D7qz1kEfGD2LY78lusg7I@public.gmane.org/>
  0 siblings, 1 reply; 6+ messages in thread
From: bugzilla-daemon-CC+yJ3UmIYqDUpFQwHEjaQ @ 2015-05-16 15:14 UTC (permalink / raw)
  To: nouveau-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW


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https://bugs.freedesktop.org/show_bug.cgi?id=90482

            Bug ID: 90482
           Summary: Xorg take 100% CPU when using multiple independent
                    screen configuration
           Product: xorg
           Version: unspecified
          Hardware: x86-64 (AMD64)
                OS: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Driver/nouveau
          Assignee: nouveau-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org
          Reporter: dura-PlyTytoxC32F389P3+uynUB+6BGkLq7r@public.gmane.org
        QA Contact: xorg-team-go0+a7rfsptAfugRpC6u6w@public.gmane.org

Created attachment 115835
  --> https://bugs.freedesktop.org/attachment.cgi?id=115835&action=edit
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.

-- 
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You are the assignee for the bug.

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^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2019-12-04  8:59 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2015-05-16 15:14 [Bug 90482] New: Xorg take 100% CPU when using multiple independent screen configuration bugzilla-daemon-CC+yJ3UmIYqDUpFQwHEjaQ
     [not found] ` <bug-90482-8800-V0hAGp6uBxMKqLRl/0Ahz6D7qz1kEfGD2LY78lusg7I@public.gmane.org/>
2015-05-16 15:15   ` [Bug 90482] " bugzilla-daemon-CC+yJ3UmIYqDUpFQwHEjaQ
2015-05-16 20:42   ` bugzilla-daemon-CC+yJ3UmIYqDUpFQwHEjaQ
2015-05-16 20:53   ` bugzilla-daemon-CC+yJ3UmIYqDUpFQwHEjaQ
2016-10-24  9:41   ` bugzilla-daemon-CC+yJ3UmIYqDUpFQwHEjaQ
2019-12-04  8:59   ` bugzilla-daemon-CC+yJ3UmIYqDUpFQwHEjaQ

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