From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Gunthorpe Subject: Re: [ofa-general] Re: [GIT PULL] please pull ummunotify Date: Mon, 12 Oct 2009 13:30:48 -0600 Message-ID: <20091012193048.GA20313@obsidianresearch.com> References: <1253187028.8439.2.camel@twins> <1253198976.14935.27.camel@laptop> <20090929171332.GD14405@elf.ucw.cz> <20090930094456.GD24621@elte.hu> <20090930160232.GZ22310@obsidianresearch.com> <20091012181944.GF17138@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20091012181944.GF17138-X9Un+BFzKDI@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Ingo Molnar Cc: Pavel Machek , Roland Dreier , Peter Zijlstra , linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Paul Mackerras , Anton Blanchard , general-ZwoEplunGu1OwGhvXhtEPSCwEArCW2h5@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, Jeff Squyres List-Id: linux-rdma@vger.kernel.org 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. It has the same problem as perf - you either bound the number/size of filters, or let user space allocate filters until the box OOMs. perf has the additonal problem that even with filters you can still loose events if the event ring overflows. Jason -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757998AbZJLTbo (ORCPT ); Mon, 12 Oct 2009 15:31:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757917AbZJLTbn (ORCPT ); Mon, 12 Oct 2009 15:31:43 -0400 Received: from 139-142-54-143.atc.vaillant.ca ([139.142.54.143]:35542 "EHLO quartz.edm.orcorp.ca" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1757657AbZJLTbn (ORCPT ); Mon, 12 Oct 2009 15:31:43 -0400 Date: Mon, 12 Oct 2009 13:30:48 -0600 From: Jason Gunthorpe To: Ingo Molnar Cc: 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 Message-ID: <20091012193048.GA20313@obsidianresearch.com> References: <1253187028.8439.2.camel@twins> <1253198976.14935.27.camel@laptop> <20090929171332.GD14405@elf.ucw.cz> <20090930094456.GD24621@elte.hu> <20090930160232.GZ22310@obsidianresearch.com> <20091012181944.GF17138@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091012181944.GF17138@elte.hu> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. It has the same problem as perf - you either bound the number/size of filters, or let user space allocate filters until the box OOMs. perf has the additonal problem that even with filters you can still loose events if the event ring overflows. Jason