Subject: Re: O(1) scheduler & interactivity improvements
From: Felipe Alfaro Solana <felipe_alfaro@linuxmail.org>
To: Daniel Gryniewicz <dang@fprintf.net>
Cc: Helge Hafting <helgehaf@aitel.hist.no>,
       LKML <linux-kernel@vger.kernel.org>
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Date: 23 Jun 2003 20:59:31 +0200
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On Mon, 2003-06-23 at 18:21, Daniel Gryniewicz wrote:
> > So then, why I can easily starve the X11 server (which should be marked
> > interactive), Evolution or OpenOffice simply by running "while true; do
> > a=2; done". Why don't they get an increased priority boost to stop the
> > from behaving so jerky?
> 
> You're own metric will kill you here.  You're while true; loop is
> running in the shell, which is interactive (it has accepted user in put
> in the past) and can therefore easily starve anything else.  You need a
> an easy way to make an interactive process non-interactive, and that's
> what these threads are all about, making interactive threads
> non-interactive (and the other way around) in a fashion that maximises
> the user experience.  A history of user input is not necessarily a good
> metric, as many non-interactive CPU hogs start out life as interactive
> threads (like your loop above).

OK, replace "while true; ..." with a parallel kernel compile, for
example, and the effect, on a 700Mhz laptop, is nearly the same: you can
easily starve XMMS, and X11 feels jerky. Changing between virtual
desktops in KDE produces the same effect, also.

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