Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758379AbXIXLJM (ORCPT ); Mon, 24 Sep 2007 07:09:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755506AbXIXLI6 (ORCPT ); Mon, 24 Sep 2007 07:08:58 -0400 Received: from viefep18-int.chello.at ([213.46.255.22]:47040 "EHLO viefep32-int.chello.at" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754934AbXIXLI5 (ORCPT ); Mon, 24 Sep 2007 07:08:57 -0400 Date: Mon, 24 Sep 2007 13:08:51 +0200 From: Peter Zijlstra To: Mike Galbraith Cc: Tong Li , Ingo Molnar , dimm , linux-kernel@vger.kernel.org, Srivatsa Vaddagiri Subject: Re: [git] CFS-devel, group scheduler, fixes Message-ID: <20070924130851.201d18ed@twins> In-Reply-To: <1190630535.7406.2.camel@Homer.simpson.net> References: <1190144190.5204.24.camel@earth> <20070918201622.GA1632@elte.hu> <1190183324.9737.7.camel@Homer.simpson.net> <1190188261.9185.21.camel@Homer.simpson.net> <1190191368.8687.5.camel@Homer.simpson.net> <1190264114.6411.4.camel@Homer.simpson.net> <1190272507.27867.20.camel@Homer.simpson.net> <20070920075155.GA31641@elte.hu> <1190275870.9232.6.camel@Homer.simpson.net> <1190455308.7404.19.camel@Homer.simpson.net> <1190531662.11524.15.camel@Homer.simpson.net> <1190628609.6389.14.camel@Homer.simpson.net> <20070924122422.75562c41@twins> <1190630535.7406.2.camel@Homer.simpson.net> X-Mailer: Claws Mail 3.0.0 (GTK+ 2.10.11; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1504 Lines: 43 On Mon, 24 Sep 2007 12:42:15 +0200 Mike Galbraith wrote: > On Mon, 2007-09-24 at 12:24 +0200, Peter Zijlstra wrote: > > > how about something like: > > > > s64 delta = (s64)(vruntime - min_vruntime); > > if (delta > 0) > > min_vruntime += delta; > > > > That would rid us of most of the funny conditionals there. > > That still left me with negative min_vruntimes. The pinned hogs didn't > lock my box up, but I quickly got the below, so hastily killed it. > > se.wait_max : 7.846949 > se.wait_max : 301.951601 > se.wait_max : 7.071359 > Odd, the idea (which I think is clear) is that min_vruntime can wrap around the u64 spectrum. And by using min_vruntime as offset to base the key around, we get a signed but limited range key-space. (because we update min_vruntime to be the leftmost task (in a monotonic fashion)) So I'm having trouble with these patches, that is, both your wrap around condition of: if (likely(new_rq->cfs.min_vruntime)) as well as the last patchlet: if (((s64)vruntime > (s64)min_vruntime) || in that neither of these changes make sense in what its trying to do. Its perfectly valid for min_vruntime to exist in 1ULL << 63. - 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/