Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755524Ab3DVUqY (ORCPT ); Mon, 22 Apr 2013 16:46:24 -0400 Received: from mb1i1mx.ns.pitt.edu ([136.142.11.141]:42468 "EHLO mb1i1.ns.pitt.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755250Ab3DVUqW (ORCPT ); Mon, 22 Apr 2013 16:46:22 -0400 Date: Mon, 22 Apr 2013 16:46:19 -0400 From: Jiannan Ouyang Subject: Re: Preemptable Ticket Spinlock In-reply-to: <1366661294.6454.18.camel@laptop> To: Peter Zijlstra Cc: Rik van Riel , LKML , Raghavendra K T , Avi Kivity , Gleb Natapov , Ingo Molnar , Marcelo Tosatti , Srikar , "H. Peter Anvin" , "Nikunj A. Dadhania" , KVM , Thomas Gleixner , Chegu Vinod , "Andrew M. Theurer" , Srivatsa Vaddagiri , Andrew Jones , Karen Noel Message-id: MIME-version: 1.0 Content-type: text/plain; charset=ISO-8859-1 References: <51745650.9050204@redhat.com> <1366631460.4443.3.camel@laptop> <51753289.70406@redhat.com> <1366660147.6454.6.camel@laptop> <517595FA.800@redhat.com> <1366661294.6454.18.camel@laptop> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1403 Lines: 34 On Mon, Apr 22, 2013 at 4:08 PM, Peter Zijlstra wrote: > > I much prefer the entire series from Jeremy since it maintains the > ticket semantics and doesn't degrade the lock to unfair under > contention. > > Now I suppose there's a reason its not been merged yet and I suspect > its !paravirt hotpath impact which wasn't rightly justified or somesuch > so maybe someone can work on that or so.. dunno. > > In my paper, I comparable preemptable-lock and pv_lock on KVM from Raghu and Jeremy. Results show that: - preemptable-lock improves performance significantly without paravirt support - preemptable-lock can also be paravirtualized, which outperforms pv_lock, especially when overcommited by 3 or more - pv-preemptable-lock has much less performance variance compare to pv_lock, because it adapts to preemption within VM, other than using rescheduling that increase VM interference It would still be very interesting to conduct more experiments to compare these two, to see if the fairness enforced by pv_lock is mandatory, and if preemptable-lock outperforms pv_lock in most cases, and how do they work with PLE. --Jiannan -- 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/