Re: 2.4.4 sluggish under fork load

From: Peter Osterlund (
Date: Mon Apr 30 2001 - 16:45:53 EST

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 Österlund   
Sköndalsvägen 35  
S-128 66 Sköndal            +46 8 942647

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