Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932730AbZJMFpO (ORCPT ); Tue, 13 Oct 2009 01:45:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756274AbZJMFpN (ORCPT ); Tue, 13 Oct 2009 01:45:13 -0400 Received: from mail4-relais-sop.national.inria.fr ([192.134.164.105]:45639 "EHLO mail4-relais-sop.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755594AbZJMFpM (ORCPT ); Tue, 13 Oct 2009 01:45:12 -0400 X-IronPort-AV: E=Sophos;i="4.44,550,1249250400"; d="scan'208";a="48484298" Message-ID: <4AD41373.8010108@inria.fr> Date: Tue, 13 Oct 2009 07:43:15 +0200 From: Brice Goglin User-Agent: Mozilla-Thunderbird 2.0.0.22 (X11/20090706) MIME-Version: 1.0 To: Ingo Molnar CC: Jason Gunthorpe , Pavel Machek , Roland Dreier , Peter Zijlstra , linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, Paul Mackerras , Anton Blanchard , general@lists.openfabrics.org, akpm@linux-foundation.org, torvalds@linux-foundation.org, Jeff Squyres Subject: Re: [ofa-general] Re: [GIT PULL] please pull ummunotify References: <1253198976.14935.27.camel@laptop> <20090929171332.GD14405@elf.ucw.cz> <20090930094456.GD24621@elte.hu> <20090930160232.GZ22310@obsidianresearch.com> <20091012181944.GF17138@elte.hu> <20091012193048.GA20313@obsidianresearch.com> <20091012202046.GA7648@elte.hu> In-Reply-To: <20091012202046.GA7648@elte.hu> X-Enigmail-Version: 0.95.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1358 Lines: 35 Ingo Molnar wrote: > * Jason Gunthorpe wrote: > > >> On Mon, Oct 12, 2009 at 08:19:44PM +0200, Ingo Molnar wrote: >> >> >>>> After that point the scheme is perfectly lossless. >>>> >>> Well if it can OOM it's not lossless, obviously. You just define >>> "event loss" to be equivalent to "Destruction of the universe." ;-) >>> >> It can't OOM once the ummunotify registration is done - when an event >> occurs it doesn't allocate any memory and it doesn't loose events. >> > > Well, it has built-in event loss via the UMMUNOTIFY_FLAG_HINT mechanism: > any double events on the same range will cause an imprecise event to be > recorded and cause the loss of information. > The target (MPI) application doesn't care about how many events are coming here. It just needs to know whether something has been invalidated in the range. If so, it destroy the whole RDMA window anyway. So it's actually _good_ that multiple events are merged into a single one: the application only has to process a single event per partially-invalidated range. Brice -- 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/