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: Sun, 26 Jan 2020 07:35:36 -0800 Message-ID: <20200126153535.GL2935@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> <20200125045844.GC2935@paulmck-ThinkPad-P72> <967f99ee-b781-43f4-d8ba-af83786c429c@redhat.com> Reply-To: paulmck@kernel.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail.kernel.org ([198.145.29.99]:57562 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725908AbgAZPfg (ORCPT ); Sun, 26 Jan 2020 10:35:36 -0500 Content-Disposition: inline In-Reply-To: <967f99ee-b781-43f4-d8ba-af83786c429c@redhat.com> 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 On Sat, Jan 25, 2020 at 02:41:39PM -0500, Waiman Long wrote: > 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. Hmmm... Here is my kernel command line taken from the console log: console=ttyS0 locktorture.onoff_interval=0 numa_spinlock=on locktorture.stat_interval=15 locktorture.shutdown_secs=1800 locktorture.verbose=1 Yet the string "Enabling CNA spinlock" does not appear. Ah, idiot here needs to enable CONFIG_NUMA_AWARE_SPINLOCKS in his build. Trying again with "--kconfig "CONFIG_NUMA_AWARE_SPINLOCKS=y"... Thanx, Paul