Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755021Ab3DWE7z (ORCPT ); Tue, 23 Apr 2013 00:59:55 -0400 Received: from e23smtp08.au.ibm.com ([202.81.31.141]:41797 "EHLO e23smtp08.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754482Ab3DWE7y (ORCPT ); Tue, 23 Apr 2013 00:59:54 -0400 Message-ID: <51761604.6080103@linux.vnet.ibm.com> Date: Tue, 23 Apr 2013 10:33:00 +0530 From: Raghavendra K T Organization: IBM User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121029 Thunderbird/16.0.2 MIME-Version: 1.0 To: Peter Zijlstra CC: Rik van Riel , Jiannan Ouyang , LKML , 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 Subject: Re: Preemptable Ticket Spinlock 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> <5175A277.5080208@redhat.com> <1366664518.8337.21.camel@laptop> In-Reply-To: <1366664518.8337.21.camel@laptop> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13042304-5140-0000-0000-00000313EB91 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 972 Lines: 22 On 04/23/2013 02:31 AM, Peter Zijlstra wrote: > On Mon, 2013-04-22 at 16:49 -0400, Rik van Riel wrote: >> 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. > > https://lkml.org/lkml/2012/5/2/101 > > If you schedule too often your SPIN_THRESHOLD is far too low. > > Anyway.. performance can't be that bad, otherwise Jeremey would have > spend as much time on it as he did. When I experimented last time ideal SPIN_THRESHOLD for PLE machine, was around 4k, 8k. Jeremy's experiment was on a non-PLE machine AFAIK, which complemented PLE feature in a nice way with 2k threshold. -- 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/