From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934410Ab1JaLmd (ORCPT ); Mon, 31 Oct 2011 07:42:33 -0400 Received: from mailout-de.gmx.net ([213.165.64.22]:39349 "HELO mailout-de.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S933982Ab1JaLmb (ORCPT ); Mon, 31 Oct 2011 07:42:31 -0400 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX18Rp/INiKURK/ueFqweRxYrdbFzYmt293BCmvYBsK oz/R6NVYSrZLbX Subject: Re: HT (Hyper Threading) aware process scheduling doesn't work as it should From: Mike Galbraith To: Con Kolivas Cc: "Artem S. Tashkinov" , linux-kernel@vger.kernel.org In-Reply-To: <1479015.f2tEjKr9vR@quad> References: <269467866.49093.1320004632156.JavaMail.mail@webmail17> <1479015.f2tEjKr9vR@quad> Content-Type: text/plain; charset="UTF-8" Date: Mon, 31 Oct 2011 12:42:28 +0100 Message-ID: <1320061348.6389.18.camel@marge.simson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.32.1 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2011-10-31 at 21:06 +1100, Con Kolivas wrote: > On Sun, 30 Oct 2011 07:57:12 PM Artem S. Tashkinov wrote: > > I've found out that even on Linux 3.0.8 the process scheduler doesn't > > correctly distributes the load amongst virtual CPUs. E.g. on a 4-core > > system (8 total virtual CPUs) the process scheduler often run some > > instances of four different tasks on the same physical CPU. > > > Any thoughts? comments? I think this is quite a serious problem. > > Intense cache locality logic, power saving concepts, cpu frequency governor > behaviour and separate runqueues per CPU within the current CPU process > scheduler in the current mainline linux kernel will ocasionally do this. Some > workloads will be better, while others will be worse. Feel free to try my BFS > cpu scheduler if you wish a CPU process scheduler that spreads work more > evenly across CPUs. > > Alas the last version I synced up with will not apply cleanly past about 3.0.6 > I believe: > > http://ck.kolivas.org/patches/bfs/3.0.0/3.0-sched-bfs-413.patch Yeah, it handles independent tasks well, but cache misses can be excruciatingly painful for the others. Q6600 box, configs as identical as possible, tbench 8 3.0.6-bfs413 728.6 MB/sec 3.0.8 1146.7 MB/sec -Mike