From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759015Ab1FBIFC (ORCPT ); Thu, 2 Jun 2011 04:05:02 -0400 Received: from mail-yx0-f174.google.com ([209.85.213.174]:42283 "EHLO mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753021Ab1FBIEz convert rfc822-to-8bit (ORCPT ); Thu, 2 Jun 2011 04:04:55 -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:content-transfer-encoding; b=i1AaMgNPwXDCCxKAkgQEHkZlLo3xL/kIubcxIJWGj3zavRmAtxue4xlHvQSBpkxDLi Dz2s36RvMoJ3x/92sBAD8E3IJTiwEsxuE8sG+KjJ8gc74hbq5b6tBotkrTb94SGtG34O tZev0UhkmpYKW+x5fU0XCeh1MlaLKaGUMaGKg= MIME-Version: 1.0 In-Reply-To: References: Date: Thu, 2 Jun 2011 16:04:53 +0800 Message-ID: Subject: Re: [PATCH] sched: remove resetting exec_start in put_prev_task_rt() From: Yong Zhang To: Hillf Danton Cc: LKML , Steven Rostedt , Mike Galbraith , Peter Zijlstra , Ingo Molnar Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 1, 2011 at 10:03 PM, Hillf Danton wrote: > Resetting exec_start, after updated in update_curr_rt(), could open window for > messing up the subsequent computations of delta_exec of the given task. I can't see how could this happen. what kind of 'subsequent computations' do you mean? But because exec_start will be reset by _pick_next_task_rt()/set_curr_task_rt(), you patch is ok. IMHO it is not critical, it's just cleanup instead. Thanks, Yong > > Signed-off-by: Hillf Danton > --- >  kernel/sched_rt.c |    1 - >  1 files changed, 0 insertions(+), 1 deletions(-) > > diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c > index 88725c9..0f0cfce 100644 > --- a/kernel/sched_rt.c > +++ b/kernel/sched_rt.c > @@ -1166,7 +1166,6 @@ static struct task_struct > *pick_next_task_rt(struct rq *rq) >  static void put_prev_task_rt(struct rq *rq, struct task_struct *p) >  { >        update_curr_rt(rq); > -       p->se.exec_start = 0; > >        /* >         * The previous task needs to be made eligible for pushing > -- Only stand for myself