Date: Tue, 9 Mar 2004 11:41:12 -0500 (EST) From: Robert Watson <rwatson@freebsd.org> To: Bin Ren <br260@cam.ac.uk> Cc: freebsd-current@freebsd.org Subject: Re: a serious error in sched_ule.c? Message-ID: <Pine.NEB.3.96L.1040309113959.26895J-100000@fledge.watson.org> In-Reply-To: <E1B0gU0-0004ly-9M.--1c41a3d54c4fc50bd9d924e41c4ca767a2f5dfd9@maroon.csi.cam.ac.uk>
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On 9 Mar 2004, Bin Ren wrote:
> Hi, all:
>
> I've been reading sched_ule.c and seem to find a serious error:
>
> in 'sched_slice()':
>
> * Rationale:
> * KSEs in interactive ksegs get the minimum slice so that we
> * quickly notice if it abuses its advantage.
>
> Then, there is:
>
> if (!SCHED_INTERACTIVE(kg)) {
> .....
> .....
> } else
> ke->ke_slice = SCHED_SLICE_INTERACTIVE;
>
> Then, at the beginning of the file, there is:
>
> #define SCHED_SLICE_INTERACTIVE (slice_max)
>
>
> (slice_max) for interactive KSEs???? Either this is a serious mistake or
> I'm seriously missing sth here.
I believe this is a synchronization error in the comment and the code.
The code was changed to provide a maximum slice to interactive
applications because non-CPU intensive X11 applications will be marked as
interactive, but redraws get interrupted in a short slice. When the
change went in to increase the time slice I saw an observable improvement
in the redraws of X11 apps under load.
Robert N M Watson FreeBSD Core Team, TrustedBSD Projects
robert@fledge.watson.org Senior Research Scientist, McAfee Research
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