From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: [PATCH v9 0/5] Add NUMA-awareness to qspinlock Date: Fri, 24 Jan 2020 20:58:45 -0800 Message-ID: <20200125045844.GC2935@paulmck-ThinkPad-P72> 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> Reply-To: paulmck@kernel.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Waiman Long 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 List-Id: linux-arch.vger.kernel.org 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:56164 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725821AbgAYE6p (ORCPT ); Fri, 24 Jan 2020 23:58:45 -0500 Date: Fri, 24 Jan 2020 20:58:45 -0800 From: "Paul E. McKenney" Subject: Re: [PATCH v9 0/5] Add NUMA-awareness to qspinlock Message-ID: <20200125045844.GC2935@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-arch-owner@vger.kernel.org List-ID: To: Waiman Long 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 Message-ID: <20200125045845.rUzdzr_RfayrZWouEJCERoFOgOd_1gfCgTJ4ZbNr8_Q@z> 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