Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759144Ab1CDJbC (ORCPT ); Fri, 4 Mar 2011 04:31:02 -0500 Received: from mail-yw0-f46.google.com ([209.85.213.46]:34935 "EHLO mail-yw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751713Ab1CDJa7 convert rfc822-to-8bit (ORCPT ); Fri, 4 Mar 2011 04:30:59 -0500 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=gkROMLGIDJ5hMexSwGgn5QDayq6B1C2MbwQzdEIf0S5g1GKmxrUxDLxIvHwz1vTVMD 5g19qa0S1abfe3IeUXlgPrAnhz0qc+tWOqN0SlPHRKhS75oNQEp1YcbE78+7yc4oJ67m tbmNPF7YBgnQx3T5zWas/gZLIjgSFqn2rSVfM= MIME-Version: 1.0 In-Reply-To: References: <20110303113435.GA2868@balbir.in.ibm.com> <20110303140551.GA20677@zhy> <20110304072517.GC2868@balbir.in.ibm.com> Date: Fri, 4 Mar 2011 17:30:58 +0800 Message-ID: Subject: Re: [BUGFIX][PATCH] Fix sched rt group scheduling when hierachy is enabled From: Yong Zhang To: Balbir Singh Cc: "linux-kernel@vger.kernel.org" , Ingo Molnar , Peter Zijlstra , Srivatsa Vaddagiri , Bharata B Rao 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 Content-Length: 1569 Lines: 52 On Fri, Mar 4, 2011 at 4:59 PM, Balbir Singh wrote: >>>>  deactivate_task(b); /* A.throttled == 1 && A.rt_nr_running == 0 */ >>>>    do_sched_rt_period_timer(); /* A.run_time == 0 && A.throttled == 0*/ >>> >>> Note at some point rt_time becomes 0 and if enqueue is not set, the >> >> If the group should be add back, it will be at the first >> do_sched_rt_period_timer() which decreases run_time; >> > > As long as idle is 0, the period will continue to run, if it has > rt_nr_running or rt_time, the timer will run. Yep. Should be the first do_sched_rt_period_timer() which meets rt_rq->rt_time < runtime :) > >>> next do_sched_rt_period_timer() is a NOP and does not enqueue back the >>> group >> >> Otherwise it will be added back when a task is attching to it. >> >> I still can't see how a unthrottled group which has task attched stay >> unqueued. > > The other way of looking at the first change is > > Can we have rt_time as 0, rt_nr_running >=1, rt_throttled !=0 and > still not have the rt_rq enqueued? Yeah, the same question. How could we reach that? IMHO, rt_time == 0 and rt_throttled !=0 can't coexist. > > If this is not the case, we don't lose much, a quick check for > rt_nr_running and on_rt_q I don't get what you mean here. Thanks, Yong -- Only stand for myself -- 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/