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Date: Sat, 28 Apr 2001 10:54:17 -0700 (PDT)
From: Linus Torvalds <torvalds@transmeta.com>
To: Peter Osterlund <peter.osterlund@mailbox.swipnet.se>
cc: linux-kernel@vger.kernel.org
Subject: Re: 2.4.4 sluggish under fork load
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On Sat, 28 Apr 2001, Peter Osterlund wrote:
> 
> For example, when running the gcc configure script, the X mouse pointer is
> very jerky. The configure script itself runs approximately as fast as in
> 2.4.3.

Ok. Fair enough. The new "run the child first" approach has advantages,
but it is entirely possible that the advantages unfairly prioritize things
that do a lot of forking.

> Another thing is that the bash loop "while true ; do /bin/true ; done" is
> not possible to interrupt with ctrl-c.

This, however, is a bash bug, not a kernel issue. Bash does something
strange with the terminal and ignores ^C at times, and basically only
react correctly to the ^C under the right circumstances. Changing the
child to run first probably makes the pre-existing bug much easier to see.

> Reverting the fork patch makes all these problems go away on my machine.

Reverting it outright may be an acceptable approach. I'll think about
it: the arguments _for_ the patch are true and real, and it shows up as
real improvements on some things..

An alternative approach might be to not give the child the _whole_
timeslice, but give it more than half. Partition it out 66% - 33% or
something.

		Linus


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