Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754100Ab1C1NSq (ORCPT ); Mon, 28 Mar 2011 09:18:46 -0400 Received: from casper.infradead.org ([85.118.1.10]:53687 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753229Ab1C1NSo convert rfc822-to-8bit (ORCPT ); Mon, 28 Mar 2011 09:18:44 -0400 Subject: Re: [PATCH 2/5] Revert "oom: give the dying task a higher priority" From: Peter Zijlstra To: "Luis Claudio R. Goncalves" Cc: Minchan Kim , 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 In-Reply-To: <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> <20110328131029.GN19007@uudg.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Mon, 28 Mar 2011 15:18:13 +0200 Message-ID: <1301318293.4859.19.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1577 Lines: 39 On Mon, 2011-03-28 at 10:10 -0300, Luis Claudio R. Goncalves wrote: > | 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 CFS has never used rt.time_slice, that's always been a pure SCHED_RR thing. > Peter, would that be effective to boost the priority of the dying task? The thing you're currently doing, making it SCHED_FIFO ? > I mean, in the context of SCHED_OTHER tasks would it really help the dying > task to be scheduled sooner to release its resources? That very much depends on how all this stuff works, I guess if everybody serializes on OOM and only the first will actually kill a task and all the waiting tasks will try to allocate a page again before also doing the OOM thing, and the pending tasks are woken after the OOM target task has completed dying.. then I don't see much point in boosting things, since everybody interested in memory will block and eventually only the dying task will be left running. Its been a very long while since I stared at the OOM code.. > If so, as we remove > the code in commit 93b43fa5508 we should re-add that old code. It doesn't make any sense to fiddle with rt.time_slice afaict. -- 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/