Re: Terrible interactivity with 2.6.0-t9-mm3

From: Nick Piggin
Date: Sun Nov 16 2003 - 23:20:55 EST




Gene Heskett wrote:

On Sunday 16 November 2003 21:49, Andrew Morton wrote:

Gawain Lynch <gawain@xxxxxxxxxxxxxxxxxxx> wrote:

On Mon, 2003-11-17 at 08:42, Andrew Morton wrote:

Two things to try, please:

a) Is the problem from Linus's tree? Try 2.6.0-test9 plus
ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2
.6.0-test9/2.6.0-test9-mm3/broken-out/linus.patch

b) The only significant scheduler change in mm3 was
ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2
.6.0-test9/2.6.0-test9-mm3/broken-out/context-switch-accounting-f
ix.patch

So please try -mm3 with the above patch reverted with

patch -R -p1 < context-switch-accounting-fix.patch

Hi Andrew,

This is also easily reproducible here with just a kernel compile.

I have tried both a) and b) with b) not changing anything, but a)
seems to work... Anything more to try?

Your report has totally confused me. Are you saying that the
jerkiness is caused by linus.patch? Or not? Pleas try again ;)


In defense of this code, I ran -mm3 with the deadline elevator for about 3 days and was very happy with the interactivity. Now I've been running with the elevator=cfq for most of the day, and it also seems to be pretty responsive. The default as wasn't, at least for -mm2, and I haven't tried it yet for -mm3. Should I, and report back in a day or so so that you've got reports from an otherwise identical system to compare?


I think you might have confused Andrew a bit more ;)

To start with, you are talking about IO schedulers, while the thread
is about CPU interactivity.

The problem here looks like something that is caused by something in mm3,
not in mm2, not linus.patch, and not context-switch-accounting-fix.patch.


Off topic: it would be good if you could try the as disk scheduler in mm3.
I recall you had some problems with it earlier, but they should be fixed in
mm3. Thanks.


We need a test suite for this :)


Subjective reports from our base of beta testers has proven to be the
best thing.


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