[RC5] Re: [PATCH] small scheduling optimization

Kurt Garloff K.Garloff at ping.de
Mon Apr 12 09:33:35 EDT 1999


On Sun, Apr 11, 1999 at 07:36:08PM +0200, Rik van Riel wrote:
> This second patch is just a small optimization to the code calling
> the scheduling code.  With a program like rc5des running (nice +19)
> in the background and NOTHING in the foreground Linux still goes
> through the scheduler 50 times a second!
> 
> This small patch solves that problem by simply not rescheduling
> if there's nothing else to be run.  A quite similar change has
> increased someone's rc5des keyrate by 3%, but it's probably
> somewhat less on modern systems.  The effect is too small to
> really care about the change, but IMHO it's the Right Thing(tm)!

Thanks for your patch. It looks correct to me, but:

It might be that your patch is not fully correct or that you uncovered
another incorrectness, but I started to get problems with my modem tools
(mgetty+sendfax+voice): vm play -s file.rmd plays files half-way only.

I'm back to an unpatched kernel, but I can inspect further, if you want me
to. 

-- 
Dipl.Phys. Kurt Garloff <kurt at garloff.de>               [Wuppertal, FRG]
Plasma physics, high perf. computing              [Linux-ix86,-axp, DUX]
PGP key: see mailheader / key servers         [Linux SCSI driver: DC390]
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