Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752191AbZCIN3z (ORCPT ); Mon, 9 Mar 2009 09:29:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752793AbZCIN2F (ORCPT ); Mon, 9 Mar 2009 09:28:05 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:36711 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752622AbZCIN2C (ORCPT ); Mon, 9 Mar 2009 09:28:02 -0400 Subject: Re: [patch] Re: scheduler oddity [bug?] From: Peter Zijlstra To: Mike Galbraith Cc: Ingo Molnar , Balazs Scheidler , linux-kernel@vger.kernel.org, Willy Tarreau In-Reply-To: <1236604563.6027.8.camel@marge.simson.net> References: <1236448069.16726.21.camel@bzorp.balabit> <1236505323.6281.57.camel@marge.simson.net> <1236506309.6972.8.camel@marge.simson.net> <20090308153956.GB19658@elte.hu> <1236529200.7110.16.camel@marge.simson.net> <20090308175255.GA22802@elte.hu> <1236585731.6118.24.camel@marge.simson.net> <20090309080714.GB24904@elte.hu> <1236596664.8389.331.camel@laptop> <1236604563.6027.8.camel@marge.simson.net> Content-Type: text/plain Date: Mon, 09 Mar 2009 14:27:47 +0100 Message-Id: <1236605267.8389.490.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.25.92 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1206 Lines: 32 On Mon, 2009-03-09 at 14:16 +0100, Mike Galbraith wrote: > On Mon, 2009-03-09 at 12:04 +0100, Peter Zijlstra wrote: > > > OK, talked a bit with Ingo, the reason you're doing is that avg_overlap > > can easily grow stale.. I can see that happen indeed. > > > > So the 'perfect' thing would be a task-runtime decay, barring that the > > preemption thing seems a sane enough hart-beat of a task. > > > > How does the below look to you? > > Other than the fact that the test for sync reject is currently > avg_overlap > sysctl_sched_migration_cost, looks fine to me. Having it > capped at the boundary is probably the better way to go. Ah, yes, and looking at update_avg() we'll also discard the lower 3 bits, so we'll never actually reach. So I guess it should read something like: update_avg(&prev->se.avg_overlap, 2*sysctl_sched_migration_cost); or somesuch. Does it actually solve the reported problem? I've only thought about the issue so far :-) -- 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/