Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754089Ab1EKRxx (ORCPT ); Wed, 11 May 2011 13:53:53 -0400 Received: from mail-wy0-f174.google.com ([74.125.82.174]:42081 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753927Ab1EKRxu (ORCPT ); Wed, 11 May 2011 13:53:50 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=QRrC0So7Jwk8gKfEChzx8V3PD28hRD1s7ZZcc5/JpXzxHCQOjWITpza/vBWSc2csh1 OXsFnRXJ1P6+xsZdVn8y2XKySbb6soauI8HDvaOml72p5oN+VuGoOil8pc5fNedXg36f lKjysNep09HVpavRFYTtKJ1VLqkbi0+tKcsi0= MIME-Version: 1.0 In-Reply-To: References: Date: Wed, 11 May 2011 21:44:04 +0800 Message-ID: Subject: Re: [PATCH] sched: correct how RT task is picked From: Hillf Danton To: Yong Zhang Cc: LKML , Ingo Molnar , Peter Zijlstra , Mike Galbraith Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1200 Lines: 29 On Wed, May 11, 2011 at 4:43 PM, Yong Zhang wrote: > On Tue, May 10, 2011 at 9:04 PM, Hillf Danton wrote: >> When picking RT task for given CPU, >> [1] if the cpu is invalid for cpumask test, right result could not be > > 'cpu is invalid' means weather we care it or not, it's not real 'invalid' > If cpu is not cared, how to determine whether it is allowed for task to run? >> reached even by further checking nr_cpus_allowed, >> on the other hand, the input cpu is valid in two cases that >> pick_next_highest_task_rt() is called, thus the invalid input cpu >> looks over-concern. >> [2] if the cpu is valid for cpumask test, further checking >> nr_cpus_allowed looks overwork, since it is computed based on >> cpus_allowed, > > No, cpumask_test_cpu(cpu, &p->cpus_allowed) doesn't mean > p->rt.nr_cpus_allowed > 1. > If cpu is allowed for task to run, then why more cpus are enforced? thanks Hillf -- 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/