From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [ofa-general] Re: [GIT PULL] please pull ummunotify Date: Tue, 29 Sep 2009 19:13:32 +0200 Message-ID: <20090929171332.GD14405@elf.ucw.cz> References: <1253187028.8439.2.camel@twins> <1253198976.14935.27.camel@laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Roland Dreier Cc: 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, Ingo Molnar List-Id: linux-rdma@vger.kernel.org On Thu 2009-09-17 08:45:29, Roland Dreier wrote: > > > > > Hmm, or are you saying you can only get 1 event per registered range and > > > > allocate the thing on registration? That'd need some registration limit > > > > to avoid DoS scenarios. > > > > > > Yes, that's what I do. You're right, I should add a limit... although > > > their are lots of ways for userspace to consume arbitrary amounts of > > > kernel resources already. > > > > I'd be good to work at reducing that number, not adding to it ;-) > > Yes, definitely. I'll add a quick ummunotify module parameter that > limits the number of registrations per process. > > > But yeah, I currently don't see a very nice match to perf counters. > > OK. It would be nice to tie into something more general, but I think I > agree -- perf counters are missing the filtering and the "no lost > events" that ummunotify does have. And I'm not sure it's worth messing > up the perf counters design just to jam one more not totally related > thing in. I believe that extending perf counters to do what you want is better than adding one more, very strange, user<->kernel interface. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- 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 S1753487AbZI2RNk (ORCPT ); Tue, 29 Sep 2009 13:13:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753453AbZI2RNj (ORCPT ); Tue, 29 Sep 2009 13:13:39 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:42376 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753449AbZI2RNi (ORCPT ); Tue, 29 Sep 2009 13:13:38 -0400 Date: Tue, 29 Sep 2009 19:13:32 +0200 From: Pavel Machek To: Roland Dreier Cc: 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, Ingo Molnar Subject: Re: [ofa-general] Re: [GIT PULL] please pull ummunotify Message-ID: <20090929171332.GD14405@elf.ucw.cz> References: <1253187028.8439.2.camel@twins> <1253198976.14935.27.camel@laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 2009-09-17 08:45:29, Roland Dreier wrote: > > > > > Hmm, or are you saying you can only get 1 event per registered range and > > > > allocate the thing on registration? That'd need some registration limit > > > > to avoid DoS scenarios. > > > > > > Yes, that's what I do. You're right, I should add a limit... although > > > their are lots of ways for userspace to consume arbitrary amounts of > > > kernel resources already. > > > > I'd be good to work at reducing that number, not adding to it ;-) > > Yes, definitely. I'll add a quick ummunotify module parameter that > limits the number of registrations per process. > > > But yeah, I currently don't see a very nice match to perf counters. > > OK. It would be nice to tie into something more general, but I think I > agree -- perf counters are missing the filtering and the "no lost > events" that ummunotify does have. And I'm not sure it's worth messing > up the perf counters design just to jam one more not totally related > thing in. I believe that extending perf counters to do what you want is better than adding one more, very strange, user<->kernel interface. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html