On Fri, 2008-01-18 at 13:34 +0100, Michel Dänzer wrote:

This is on a PowerBook5,8.

In a nutshell, things seem more sluggish in general than with 2.6.23.
But in particular, processes running at nice levels >0 can get most of
the CPU cycles available, slowing down processes running at nice level
0.

The canonical test case I've come up with is to run an infinite loop
with

sudo -u nobody nice -n 19 sh -c 'while true; do true; done'

This makes my X session (X server running at nice level -1, clients at
0) unusably sluggish (it can even take several seconds to process ctrl-c
to interrupt the infinite loop) with 2.6.24-rc but works as expected
with 2.6.23.

Anybody else seeing this?

I've seen this since .24-rc5 (the first .24-rc I tried), and it's still
there with -rc8. I'd be surprised if this kind of behaviour remained
unfixed for that long if it affected x86, so  I presume it's powerpc
specific.

Or maybe not... I've bisected this down to the scheduler changes between
df3d80f5a5c74168be42788364d13cf6c83c7b9c/23fd50450a34f2558070ceabb0bfebc1c9604af5 and b5869ce7f68b233ceb81465a7644be0d9a5f3dbb . I'll try and bisect it further, but this is my main work machine, so I can't reboot it too often. I'm CC'ing Ingo in case he has any ideas offhand.


-- 
Earthling Michel Dänzer           |          http://tungstengraphics.com
Libre software enthusiast         |          Debian, X and DRI developer