Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753996Ab1C1NKo (ORCPT ); Mon, 28 Mar 2011 09:10:44 -0400 Received: from mail-ew0-f46.google.com ([209.85.215.46]:37916 "EHLO mail-ew0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752923Ab1C1NKm (ORCPT ); Mon, 28 Mar 2011 09:10:42 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=nXigBwjKYZpRskK/wiff8leeeHlZXv8XDvoO8EwYPR3djrMqx8S3ceafV2ihMdYlq3 fFGxuEuN23wHnNDdwo6fKvpmi7AZuWDSzLXsiqOQkbA1dlXeMh56+4c1m73iDs5XVjiJ 2U9qCBFLfcdXC4g4GS13u/a/riKzh05xKxPVc= Date: Mon, 28 Mar 2011 10:10:29 -0300 From: "Luis Claudio R. Goncalves" To: Minchan Kim Cc: Peter Zijlstra , KOSAKI Motohiro , linux-kernel@vger.kernel.org, Andrew Morton , David Rientjes , Linus Torvalds , Rik van Riel , Oleg Nesterov , linux-mm , Andrey Vagin , Hugh Dickins , KAMEZAWA Hiroyuki Subject: Re: [PATCH 2/5] Revert "oom: give the dying task a higher priority" Message-ID: <20110328131029.GN19007@uudg.org> References: <20110315153801.3526.A69D9226@jp.fujitsu.com> <20110322194721.B05E.A69D9226@jp.fujitsu.com> <20110322200657.B064.A69D9226@jp.fujitsu.com> <20110324152757.GC1938@barrios-desktop> <1301305896.4859.8.camel@twins> <20110328122125.GA1892@barrios-desktop> <1301315307.4859.13.camel@twins> <20110328124025.GC1892@barrios-desktop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110328124025.GC1892@barrios-desktop> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2623 Lines: 60 On Mon, Mar 28, 2011 at 09:40:25PM +0900, Minchan Kim wrote: | On Mon, Mar 28, 2011 at 02:28:27PM +0200, Peter Zijlstra wrote: | > On Mon, 2011-03-28 at 21:21 +0900, Minchan Kim wrote: | > > Hi Peter, | > > | > > On Mon, Mar 28, 2011 at 11:51:36AM +0200, Peter Zijlstra wrote: | > > > On Fri, 2011-03-25 at 00:27 +0900, Minchan Kim wrote: | > > > > | > > > > At that time, I thought that routine is meaningless in non-RT scheduler. | > > > > So I Cced Peter but don't get the answer. | > > > > I just want to confirm it. | > > > | > > > Probably lost somewhere in the mess that is my inbox :/, what is the | > > > full question? | > > | > > The question is we had a routine which change rt.time_slice with HZ to | > > accelarate task exit. But when we applied 93b43fa5508, we found it isn't effective | > > any more about normal task. So we removed it. Is it right? | > | > rt.time_slice is only relevant to SCHED_RR, since you seem to use | > SCHED_FIFO (which runs for as long as the task is runnable), its | > completely irrelevant. | > | > > And Kosaki is about to revert 93b43fa5508 to find out the problem of this thread | > > and Luis said he has a another solution to replace 93b43fa5508. | > > If rt.time_slice handleing is effective, we should restore it until Luis's patch | > > will be merged. | > | > Right, so only SCHED_RR is affected by time_slice, it will be | > decremented on tick (so anything that avoids ticks will also avoid the | > decrement) and once it reaches 0 the task will be queued at the tail of | > its static priority and reset the slice. If there is no other task on | > that same priority we'll again schedule that task. | > | > In short, don't use SCHED_RR and don't worry about time_slice. | | There was meaningless code in there. I guess it was in there from CFS. | Thanks for the explanation, Peter. Yes, it was CFS related: p = find_lock_task_mm(p); ... p->rt.time_slice = HZ; <<---- THIS Peter, would that be effective to boost the priority of the dying task? I mean, in the context of SCHED_OTHER tasks would it really help the dying task to be scheduled sooner to release its resources? If so, as we remove the code in commit 93b43fa5508 we should re-add that old code. Luis -- [ Luis Claudio R. Goncalves Red Hat - Realtime Team ] [ Fingerprint: 4FDD B8C4 3C59 34BD 8BE9 2696 7203 D980 A448 C8F8 ] -- 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/