From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx107.postini.com [74.125.245.107]) by kanga.kvack.org (Postfix) with SMTP id 975C06B002C for ; Sun, 5 Feb 2012 07:17:05 -0500 (EST) Message-ID: <4F2E7311.8060808@redhat.com> Date: Sun, 05 Feb 2012 14:16:17 +0200 From: Avi Kivity MIME-Version: 1.0 Subject: Re: [v7 0/8] Reduce cross CPU IPI interference References: <1328117722.2446.262.camel@twins> <20120201184045.GG2382@linux.vnet.ibm.com> <20120201201336.GI2382@linux.vnet.ibm.com> <4F2A58A1.90800@redhat.com> <20120202153437.GD2518@linux.vnet.ibm.com> <4F2AB66C.2030309@redhat.com> <20120202170134.GM2518@linux.vnet.ibm.com> <4F2AC69B.7000704@redhat.com> <20120202175155.GV2518@linux.vnet.ibm.com> In-Reply-To: <20120202175155.GV2518@linux.vnet.ibm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: paulmck@linux.vnet.ibm.com Cc: Christoph Lameter , Peter Zijlstra , Gilad Ben-Yossef , linux-kernel@vger.kernel.org, Chris Metcalf , Frederic Weisbecker , linux-mm@kvack.org, Pekka Enberg , Matt Mackall , Sasha Levin , Rik van Riel , Andi Kleen , Mel Gorman , Andrew Morton , Alexander Viro , Michal Nazarewicz , Kosaki Motohiro , Milton Miller On 02/02/2012 07:51 PM, Paul E. McKenney wrote: > On Thu, Feb 02, 2012 at 07:23:39PM +0200, Avi Kivity wrote: > > On 02/02/2012 07:01 PM, Paul E. McKenney wrote: > > > > > > > > It's not called (since the cpu is not idle). Instead we call > > > > rcu_virt_note_context_switch(). > > > > > > Frederic's work checks to see if there is only one runnable user task > > > on a given CPU. If there is only one, then the scheduling-clock interrupt > > > is turned off for that CPU, and RCU is told to ignore it while it is > > > executing in user space. Not sure whether this covers KVM guests. > > > > Conceptually it's the same. Maybe it needs adjustments, since kvm > > enters a guest in a different way than the kernel exits to userspace. > > > > > In any case, this is not yet in mainline. > > > > Let me know when it's in, and I'll have a look. > > Could you please touch base with Frederic Weisbecker to make sure that > what he is doing works for you? > Looks like there are new rcu_user_enter() and rcu_user_exit() APIs which we can use. Hopefully they subsume rcu_virt_note_context_switch() so we only need one set of APIs. -- error compiling committee.c: too many arguments to function -- 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