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Date: Mon, 30 Apr 2001 23:45:53 +0200 (CEST)
From: Peter Osterlund <peter.osterlund@mailbox.swipnet.se>
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To: Andrea Arcangeli <andrea@suse.de>
cc: Linus Torvalds <torvalds@transmeta.com>,
        Mark Hahn <hahn@coffee.psychology.mcmaster.ca>,
        "Adam J. Richter" <adam@yggdrasil.com>, <linux-kernel@vger.kernel.org>
Subject: Re: 2.4.4 sluggish under fork load
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On Mon, 30 Apr 2001, Andrea Arcangeli wrote:

> please try to reproduce the bad behaviour with 2.4.4aa2. There's a bug
> in the parent-timeslice patch in 2.4 that I fixed while backporting it
> to 2.2aa and that I now forward ported the fix to 2.4aa. The fact
> 2.4.4 gives the whole timeslice to the child just gives more light to
> such bug. Unfortunately the fix doesn't apply cleanly to 2.4.4 (it's
> incremental with the numa-scheduler patch) and I need to finish a few
> more things before I can backport it myself.

I applied the 10_parent-timeslice-5 patch to 2.4.4 and tested. (If I
understood correctly, the idea of that patch is to give the remaining
child time-slice back to the parent when the child exits, but only if
there have been no time-slice recalculation since the child was created.)

It is somewhat better than plain 2.4.4, but not much. I still see
scheduling delays in the range 30-120ms when running "./fork 0.4". (fork
is a program that starts a child, the child busy waits some time (0.4s)
and then exits. The parent then immediately respawns another child, etc.
See one of my previous messages.)

-- 
Peter ?sterlund             peter.osterlund@mailbox.swipnet.se
Sk?ndalsv?gen 35            http://home1.swipnet.se/~w-15919
S-128 66 Sk?ndal            +46 8 942647
Sweden


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