From mboxrd@z Thu Jan 1 00:00:00 1970 From: Waiman Long Subject: Re: [PATCH v9 0/5] Add NUMA-awareness to qspinlock Date: Sat, 25 Jan 2020 14:41:39 -0500 Message-ID: <967f99ee-b781-43f4-d8ba-af83786c429c@redhat.com> References: <20200115035920.54451-1-alex.kogan@oracle.com> <20200124222434.GA7196@paulmck-ThinkPad-P72> <6AAE7FC6-F5DE-4067-8BC4-77F27948CD09@oracle.com> <20200125005713.GZ2935@paulmck-ThinkPad-P72> <02defadb-217d-7803-88a1-ec72a37eda28@redhat.com> <20200125045844.GC2935@paulmck-ThinkPad-P72> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:22794 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726780AbgAYTlw (ORCPT ); Sat, 25 Jan 2020 14:41:52 -0500 In-Reply-To: <20200125045844.GC2935@paulmck-ThinkPad-P72> Content-Language: en-US Sender: linux-arch-owner@vger.kernel.org List-ID: To: paulmck@kernel.org Cc: Alex Kogan , linux@armlinux.org.uk, Peter Zijlstra , Ingo Molnar , Will Deacon , Arnd Bergmann , linux-arch@vger.kernel.org, linux-arm-kernel , linux-kernel@vger.kernel.org, tglx@linutronix.de, bp@alien8.de, hpa@zytor.com, x86@kernel.org, guohanjun@huawei.com, jglauber@marvell.com, dave.dice@oracle.com, steven.sistare@oracle.com, daniel.m.jordan@oracle.com On 1/24/20 11:58 PM, Paul E. McKenney wrote: > On Fri, Jan 24, 2020 at 09:17:05PM -0500, Waiman Long wrote: >> On 1/24/20 8:59 PM, Waiman Long wrote: >>>> You called it! I will play with QEMU's -numa argument to see if I can get >>>> CNA to run for me. Please accept my apologies for the false alarm. >>>> >>>> Thanx, Paul >>>> >>> CNA is not currently supported in a VM guest simply because the numa >>> information is not reliable. You will have to run it on baremetal to >>> test it. Sorry for that. >> Correction. There is a command line option to force CNA lock to be used >> in a VM. Use the "numa_spinlock=on" boot command line parameter. > As I understand it, I need to use a series of -numa arguments to qemu > combined with the numa_spinlock=on (or =1) on the kernel command line. > If the kernel thinks that there is only one NUMA node, it appears to > avoid doing CNA. > > Correct? > > Thanx, Paul > In auto-detection mode (the default), CNA will only be turned on when paravirt qspinlock is not enabled first and there are at least 2 numa nodes. The "numa_spinlock=on" option will force it on even when both of the above conditions are false. Cheers, Longman