Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753980Ab0KSOeK (ORCPT ); Fri, 19 Nov 2010 09:34:10 -0500 Received: from mail1-relais-roc.national.inria.fr ([192.134.164.82]:15860 "EHLO mail1-relais-roc.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752754Ab0KSOeI (ORCPT ); Fri, 19 Nov 2010 09:34:08 -0500 X-Greylist: delayed 587 seconds by postgrey-1.27 at vger.kernel.org; Fri, 19 Nov 2010 09:34:07 EST X-IronPort-AV: E=Sophos;i="4.59,223,1288566000"; d="scan'208";a="88743548" Date: Fri, 19 Nov 2010 15:24:18 +0100 From: Samuel Thibault To: Peter Zijlstra Cc: Linus Torvalds , Mike Galbraith , Hans-Peter Jansen , linux-kernel@vger.kernel.org, Lennart Poettering , david@lang.hm, Dhaval Giani , Vivek Goyal , Oleg Nesterov , Markus Trippelsdorf , Mathieu Desnoyers , Ingo Molnar , Balbir Singh Subject: Re: [RFC/RFT PATCH v3] sched: automated per tty task groups Message-ID: <20101119142418.GN6554@const.bordeaux.inria.fr> Mail-Followup-To: Samuel Thibault , Peter Zijlstra , Linus Torvalds , Mike Galbraith , Hans-Peter Jansen , linux-kernel@vger.kernel.org, Lennart Poettering , david@lang.hm, Dhaval Giani , Vivek Goyal , Oleg Nesterov , Markus Trippelsdorf , Mathieu Desnoyers , Ingo Molnar , Balbir Singh References: <20101116211431.GA15211@tango.0pointer.de> <201011182333.48281.hpj@urpla.net> <20101118231218.GX6024@const.famille.thibault.fr> <1290123351.18039.49.camel@maggy.simson.net> <20101118234339.GA6024@const.famille.thibault.fr> <20101119000204.GE6024@const.famille.thibault.fr> <20101119000720.GF6024@const.famille.thibault.fr> <1290167844.2109.1560.camel@laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1290167844.2109.1560.camel@laptop> User-Agent: Mutt/1.5.12-2006-07-14 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1421 Lines: 32 Peter Zijlstra, le Fri 19 Nov 2010 12:57:24 +0100, a ?crit : > On Fri, 2010-11-19 at 01:07 +0100, Samuel Thibault wrote: > > Also note that having a hierarchical process structure should permit to > > make things globally more efficient: avoid putting e.g. your cpp, cc1, > > and asm processes at three corners of your 4-socket NUMA machine :) > > And no, using that to load-balance between CPUs doesn't necessarily help > with the NUMA case, It doesn't _necessarily_ help, but it should help in quite a few cases. > load-balancing is an impossible job (equivalent to > page-replacement -- you simply don't know the future), applications > simply do wildly weird stuff. Sure. Not a reason not to get the low-hanging fruits :) > From a process hierarchy there's absolutely no difference between a > cc1/cpp/asm and some MPI jobs, both can be parent-child relations with > pipes between, some just run short and have data affinity, others run > long and don't have any. MPI jobs typically communicate with each other. Keeping them on the same socket permits to keep shared-memory MPI drivers to mostly remain in e.g. the L3 cache. That typically gives benefits. Samuel -- 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/