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Subject: Re: weird X problem - priority inversion?
From: Lee Revell <rlrevell@joe-job.com>
To: David Lang <dlang@digitalinsight.com>
Cc: Ingo Molnar <mingo@elte.hu>, linux-kernel <linux-kernel@vger.kernel.org>
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Date: Fri, 27 May 2005 13:39:17 -0400
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On Fri, 2005-05-27 at 10:34 -0700, David Lang wrote:
> On Fri, 27 May 2005, Lee Revell wrote:
> 
> > On Mon, 2005-05-23 at 01:11 -0700, David Lang wrote:
> >> remember that the low pri screensaver is just generating the image to be
> >> displayed, it's the high pri X server that's actually doing the work to
> >> display it.
> >
> > Then there needs to be some mechanism to handle it, either in X or the
> > kernel.  Other OSes do not require you to turn off the screensaver to
> > avoid a DoS - they do the obvious thing and run the screensaver at the
> > lowest priority.
> >
> > The problem may be software 3D rendering (I did not have the VIA driver
> > enabled as I did not realize it was in the kernel yet).   Maybe the X
> > server should do the work in a low priority thread.  But it sure
> > shouldn't DoS the system.  Other OSes do not have this problem.
> 
> Actually they don't (or at least didn't the last time I took windows 
> training), if you have a CPU intensive screen saver on a windows server it 
> will seriously load down the box when it kicks in.

That was a problem in the NT 4.0 days, but not lately.

Lee