From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rik van Riel Subject: Re: Preemptable Ticket Spinlock Date: Mon, 22 Apr 2013 16:49:59 -0400 Message-ID: <5175A277.5080208@redhat.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Peter Zijlstra , 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 To: Jiannan Ouyang Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 04/22/2013 04:46 PM, Jiannan Ouyang wrote: > 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. Given the fairly high cost of rescheduling a VCPU (which is likely to include an IPI), versus the short hold time of most spinlocks, I have the strong suspicion that your approach would win. The fairness is only compromised in a limited way and in certain circumstances, so I am not too worried about that. -- All rights reversed