From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB4D2C2D0DB for ; Sun, 26 Jan 2020 22:42:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 96A4420720 for ; Sun, 26 Jan 2020 22:42:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580078568; bh=XMfKPd5GXkrw5+jrBxAKJBcVLbkHH3KxZoDRS8H0/tw=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:List-ID: From; b=ranzkNCpzfEoNorjzc5vt/oBGVZ/qykB1Trk+MZENDgY5k0tRhL9SLoXTfuRTZduM wW9BafDPiq4TgzIxPbsP6WocYzwbpunAvDsOC9fuUw/PNTTI+bvwwdoIHEAacNJ8MR yrbswTWDR7mJ3J0JPucj1gH41fGF4CTkoKBaswsw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727349AbgAZWmr (ORCPT ); Sun, 26 Jan 2020 17:42:47 -0500 Received: from mail.kernel.org ([198.145.29.99]:45326 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726144AbgAZWmq (ORCPT ); Sun, 26 Jan 2020 17:42:46 -0500 Received: from paulmck-ThinkPad-P72.home (199-192-87-166.static.wiline.com [199.192.87.166]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C32F72070A; Sun, 26 Jan 2020 22:42:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580078565; bh=XMfKPd5GXkrw5+jrBxAKJBcVLbkHH3KxZoDRS8H0/tw=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=CQ+uBEyqUEqPKxMMfVbp1UPlZHy3zTK2tzOYzmjoi24+o9VX43u31KuQulWQn+e2R dRgBtsQ5HmolUh73G53VIe9B0DJIW37DKT0i+hdb8ZSnztGtS18uYqAAvG6CM7lXoR 0KeVbFop5BtjEUoT0qH93fdmEAp+PFbdRyNkWtL8= Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id 3CC5B352279E; Sun, 26 Jan 2020 14:42:45 -0800 (PST) Date: Sun, 26 Jan 2020 14:42:45 -0800 From: "Paul E. McKenney" 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 Subject: Re: [PATCH v9 0/5] Add NUMA-awareness to qspinlock Message-ID: <20200126224245.GA22901@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> <20200125045844.GC2935@paulmck-ThinkPad-P72> <967f99ee-b781-43f4-d8ba-af83786c429c@redhat.com> <20200126153535.GL2935@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200126153535.GL2935@paulmck-ThinkPad-P72> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jan 26, 2020 at 07:35:35AM -0800, Paul E. McKenney wrote: > 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"... And after fixing that, plus adding the other three Kconfig options required to enable this, I really do see "Enabling CNA spinlock" in the console log. Yay! At the end of the 30-minute locktorture exclusive-lock run, I see this: Writes: Total: 572176565 Max/Min: 54167704/10878216 ??? Fail: 0 This is about a five-to-one ratio. Is this expected behavior, given a single NUMA node on a single-socket system with 12 hardware threads? I will try reader-writer lock next. Again, should I be using qemu's -numa command-line option to create nodes? If so, what would be a sane configuration given 12 CPUs and 512MB of memory for the VM? If not, what is a good way to exercise CNA's NUMA capabilities within a guest OS? Thanx, Paul