Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964808AbWH1LEU (ORCPT ); Mon, 28 Aug 2006 07:04:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964813AbWH1LEU (ORCPT ); Mon, 28 Aug 2006 07:04:20 -0400 Received: from e35.co.us.ibm.com ([32.97.110.153]:24995 "EHLO e35.co.us.ibm.com") by vger.kernel.org with ESMTP id S964808AbWH1LES (ORCPT ); Mon, 28 Aug 2006 07:04:18 -0400 Date: Mon, 28 Aug 2006 16:33:30 +0530 From: Srivatsa Vaddagiri To: Kirill Korotaev Cc: Ingo Molnar , Nick Piggin , Sam Vilain , linux-kernel@vger.kernel.org, Kirill Korotaev , Mike Galbraith , Balbir Singh , sekharan@us.ibm.com, Andrew Morton , nagar@watson.ibm.com, matthltc@us.ibm.com, dipankar@in.ibm.com Subject: Re: [PATCH 1/7] CPU controller V1 - split runqueue Message-ID: <20060828110330.GA30090@in.ibm.com> Reply-To: vatsa@in.ibm.com References: <20060820174015.GA13917@in.ibm.com> <20060820174147.GB13917@in.ibm.com> <44EEEF28.4080707@sw.ru> <20060828033331.GA25119@in.ibm.com> <44F2A62C.9090609@sw.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <44F2A62C.9090609@sw.ru> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2565 Lines: 54 On Mon, Aug 28, 2006 at 12:15:40PM +0400, Kirill Korotaev wrote: > >How do you see the relation between load-balance done thr sched-domain > >heirarchy today and what will be done thr' virtal runqueues? > sorry, can't get your question. Currently, sched-domain heirarchies exist to facilitate load-balance at different levels (SMT, MC, CPU and finally Node). They have been so setup to do frequent load-balance across groups at lower levels (like SMT/CPU) than across groups across higher levels (ex: node). Also the domain defines what physical cpus you can actually balance across (which can be modified by something like exclusive cpusets). And some domains support balance-on-exec/fork while others needn't support it. The scheduler currently also relies on the load-balance done thr' this mechanism to keep each physical CPU busy with work. When CPUs are left idle because of this mechanism, it may be on purpose (for example the recent HT/MC optimizations, where we strive to keep each package busy rather than each CPU - achieved thr' i think active_load_balance). My question was: when you wanted to exploit the physical vs virtual runqueue separation on each CPU for load-balance purpose, how would that play with the above mentioned sched-domain based load-balance mechanisms? For example: we need to preserve the HT/MC optimizations handled in sched-domains code currently. > When I talked with Nick Piggin on summit he was quite optimistic > with such an approach. And again, this invasiveness is very simple > so I do not forsee much objections. Ingo/Nick, what do you think? If we decide that is a usefull thing to try, I can see how these mechanisms will be usefull for general SMP systems too (w/o depending on resource management). > >I will however let the maintainers > >decide on that. Sending some patches also probably will help measure this > >"invasiveness/acceptability". > I propose to work on this together helping each other. > This makes part of your patches simlper and ours as well. > And what is good allows different approaches with different properties to > be used. Are you advocating that we should be able to switch between approaches at run-time? Linux (for some good reasons perhaps) has avoided going that route so far (ex: pluggable schedulers). -- Regards, vatsa - 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/