Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751966AbaJDJWN (ORCPT ); Sat, 4 Oct 2014 05:22:13 -0400 Received: from webbox4.loswebos.de ([213.187.93.205]:44529 "EHLO webbox4.loswebos.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750923AbaJDJWL (ORCPT ); Sat, 4 Oct 2014 05:22:11 -0400 Date: Sat, 4 Oct 2014 11:22:05 +0200 From: Marc Burkhardt To: "Steinar H. Gunderson" Cc: Marc Burkhardt , linux-kernel@vger.kernel.org Subject: Re: Slowdown due to threads bouncing between HT cores Message-ID: <20141004092205.GA12973@localhost> References: <20141003194428.GA27084@sesse.net> <20141003211152.GB3889@localhost> <20141003211417.GA17326@sesse.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141003211417.GA17326@sesse.net> X-PGP-Fingerprint: D514 7DC1 B5F5 8989 083E 38C9 5ECF E5BD 3430 ABF5 X-PGP-Key: http://marc.ngoe.de/pubkey.asc X-Operating-System: Linux marc 3.10.55-desper User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Steinar H. Gunderson [2014-10-03 23:14:17 +0200]: > On Fri, Oct 03, 2014 at 11:11:52PM +0200, Marc Burkhardt wrote: > > As I understand your mail, you problem is quite similar, isn't it? > > I guess it depends on how often your process migrates. If it happens, like, > every second, it's not a big problem (and probably is expected). > If it happens all the time, it might be; it depends a bit on a number of > factors. Hi Steinar, you say the behavior is probably expected, but I still don't get the point why this could be normal or even wanted. There's a cost for migrating the process to another CPU. In case my machine has 4 cores, 3 of them 'idle' and that 1 running process that keeps being migrated ... where's the benefit of migrating it? Do you have any source/docs where I could read about this? Thanks, Marc > > /* Steinar */ > -- > Homepage: http://www.sesse.net/ > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- Marc Burkhardt -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/