From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from fg-out-1718.google.com (fg-out-1718.google.com [72.14.220.154]) by ozlabs.org (Postfix) with ESMTP id 6B881DDD0C for ; Wed, 23 Jan 2008 01:56:32 +1100 (EST) Received: by fg-out-1718.google.com with SMTP id 16so1807018fgg.39 for ; Tue, 22 Jan 2008 06:56:30 -0800 (PST) Subject: Re: ppc32: Weird process scheduling behaviour with 2.6.24-rc From: Michel =?ISO-8859-1?Q?D=E4nzer?= To: linuxppc-dev@ozlabs.org In-Reply-To: <1200659696.23161.81.camel@thor.sulgenrain.local> References: <1200659696.23161.81.camel@thor.sulgenrain.local> Content-Type: text/plain; charset=UTF-8 Date: Tue, 22 Jan 2008 15:56:26 +0100 Message-Id: <1201013786.4726.28.camel@thor.sulgenrain.local> Mime-Version: 1.0 Cc: Ingo Molnar List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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