Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756192AbZFEJv1 (ORCPT ); Fri, 5 Jun 2009 05:51:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754335AbZFEJvV (ORCPT ); Fri, 5 Jun 2009 05:51:21 -0400 Received: from smtp-out.google.com ([216.239.33.17]:4178 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753330AbZFEJvU (ORCPT ); Fri, 5 Jun 2009 05:51:20 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=mime-version:in-reply-to:references:date:message-id:subject:from:to: cc:content-type:content-transfer-encoding:x-system-of-record; b=iV6oHeTgECpp8/9fQBiuPspoOyPExQYsEfZabjPUs4eNf8yKgQVW9Ztz3+SFGZkdK 1+Wgivh/2590AnkJIjzTQ== MIME-Version: 1.0 In-Reply-To: <20090605094811.GD4601@linux.vnet.ibm.com> References: <20090604053649.GA3701@in.ibm.com> <6599ad830906050153i1afd104fqe70f681317349142@mail.gmail.com> <20090605092733.GA27486@in.ibm.com> <6599ad830906050232n11aa30d8xfcda0a279a482f32@mail.gmail.com> <20090605094811.GD4601@linux.vnet.ibm.com> Date: Fri, 5 Jun 2009 02:51:18 -0700 Message-ID: <6599ad830906050251h18f4e037h182f61aa80a5b046@mail.gmail.com> Subject: Re: [RFC] CPU hard limits From: Paul Menage To: Dhaval Giani Cc: bharata@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, Balbir Singh , Vaidyanathan Srinivasan , Gautham R Shenoy , Srivatsa Vaddagiri , Ingo Molnar , Peter Zijlstra , Pavel Emelyanov , Avi Kivity , kvm@vger.kernel.org, Linux Containers , Herbert Poetzl Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1458 Lines: 33 On Fri, Jun 5, 2009 at 2:48 AM, Dhaval Giani wrote: >> > Now if 11th group with same shares comes in, then each group will now >> > get 9% of CPU and that 10% guarantee breaks. >> >> So you're trying to guarantee 11 cgroups that they can each get 10% of >> the CPU? That's called over-committing, and while there's nothing >> wrong with doing that if you're confident that they'll not all need >> their 10% at the same time, there's no way to *guarantee* them all >> 10%. You can guarantee them all 9% and hope the extra 1% is spare for >> those that need it (over-committing), or you can guarantee 10 of them >> 10% and give the last one 0 shares. >> >> How would you propose to guarantee 11 cgroups each 10% of the CPU >> using hard limits? >> > > You cannot guarantee 10% to 11 groups on any system (unless I am missing > something). The sum of guarantees cannot exceed 100%. That's exactly my point. I was trying to counter Bharata's statement, which was: > > Now if 11th group with same shares comes in, then each group will now > > get 9% of CPU and that 10% guarantee breaks. which seemed to be implying that this was a drawback of using shares to implement guarantees. Paul -- 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/