From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx105.postini.com [74.125.245.105]) by kanga.kvack.org (Postfix) with SMTP id 982306B005D for ; Tue, 29 May 2012 14:15:39 -0400 (EDT) Date: Tue, 29 May 2012 20:15:02 +0200 From: Andrea Arcangeli Subject: Re: [PATCH 08/35] autonuma: introduce kthread_bind_node() Message-ID: <20120529181502.GM21339@redhat.com> References: <1337965359-29725-1-git-send-email-aarcange@redhat.com> <1337965359-29725-9-git-send-email-aarcange@redhat.com> <1338295753.26856.60.camel@twins> <20120529161157.GE21339@redhat.com> <1338311091.26856.146.camel@twins> <20120529174423.GK21339@redhat.com> <1338313686.26856.164.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1338313686.26856.164.camel@twins> Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Hillf Danton , Dan Smith , Linus Torvalds , Andrew Morton , Thomas Gleixner , Ingo Molnar , Paul Turner , Suresh Siddha , Mike Galbraith , "Paul E. McKenney" , Lai Jiangshan , Bharata B Rao , Lee Schermerhorn , Rik van Riel , Johannes Weiner , Srivatsa Vaddagiri , Christoph Lameter On Tue, May 29, 2012 at 07:48:06PM +0200, Peter Zijlstra wrote: > On Tue, 2012-05-29 at 19:44 +0200, Andrea Arcangeli wrote: > > > > But it'd be totally bad not to do the hard bindings to the cpu_s_ of > > the node, and not using PF_THREAD_BOUND would just allow userland to > > shoot itself in the foot. I mean if PF_THREAD_BOUND wouldn't exist > > already I wouldn't add it, but considering somebody bothered to > > implement it for the sake to make userland root user "safer", it'd be > > really silly not to take advantage of that for knuma_migrated too > > (even if it binds to more than 1 CPU). > > No, I'm absolutely ok with the user shooting himself in the foot. The > thing exists because you can crash stuff if you get it wrong with > per-cpu. > > Crashing is not good, worse performance is his own damn fault. Some people don't like root to write to /dev/mem or rm -r / either. I'm not in that camp, but if you're not in that camp, then you should _never_ care to set PF_THREAD_BOUND, no matter if it's about crashing or just slowing down the kernel. If such a thing exists, well using it to avoid the user either to crash or to screw with the system performance, can only be a bonus. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org