Re: [patch] CFS scheduler, -v18

From: Andi Kleen
Date: Wed Jul 04 2007 - 07:16:40 EST


Ingo Molnar <mingo@xxxxxxx> writes:
>
> ah. That indeed makes sense. It seems like the xterm doesnt process the
> Ctrl-C/Z keypresses _at all_ when it is 'spammed' with output. Normally,
> output 'spam' is throttled by the scroll buffer's overhead. But in
> Vegard's case, the printout involves a \r carriage return:
>
> printf("%ld\r", 1000 * clock() / CLOCKS_PER_SEC);
>
> which allows xterm-spam (attached) to easily flood the xterm (without
> any scrolling that would act as a throttle) and the xterm to flood Xorg.
>
> I suspect we need the help of an xterm/Xorg expert? (maybe Keith can
> give us further pointers? I can reproduce the problem on a T60 with i940
> and Core2Duo running Fedora 7 + Xorg 7.1.)

Xorg seems to have a couple of starvation issues. e.g. I found
the Gantt view in icemon during a busy compile session can starve all
other X clients for tenths of seconds.

-Andi
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