From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933170Ab1JaKRX (ORCPT ); Mon, 31 Oct 2011 06:17:23 -0400 Received: from home.kolivas.org ([59.167.196.135]:55304 "EHLO mine.kolivas.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932508Ab1JaKRW (ORCPT ); Mon, 31 Oct 2011 06:17:22 -0400 X-Greylist: delayed 613 seconds by postgrey-1.27 at vger.kernel.org; Mon, 31 Oct 2011 06:17:22 EDT From: Con Kolivas To: "Artem S. Tashkinov" Cc: linux-kernel@vger.kernel.org Subject: Re: HT (Hyper Threading) aware process scheduling doesn't work as it should Date: Mon, 31 Oct 2011 21:06:29 +1100 Message-ID: <1479015.f2tEjKr9vR@quad> User-Agent: KMail/4.7.2 (Linux/2.6.38.4-ck1; KDE/4.7.2; x86_64; ; ) In-Reply-To: <269467866.49093.1320004632156.JavaMail.mail@webmail17> References: <269467866.49093.1320004632156.JavaMail.mail@webmail17> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Regards, Con Kolivas -- -ck