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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham 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 EDA8CC43381 for ; Mon, 1 Apr 2019 14:36:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BB38020856 for ; Mon, 1 Apr 2019 14:36:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728554AbfDAOgY convert rfc822-to-8bit (ORCPT ); Mon, 1 Apr 2019 10:36:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53452 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726514AbfDAOgX (ORCPT ); Mon, 1 Apr 2019 10:36:23 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5BF8D882F0; Mon, 1 Apr 2019 14:36:22 +0000 (UTC) Received: from llong.remote.csb (dhcp-17-19.bos.redhat.com [10.18.17.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4E9FA19C7C; Mon, 1 Apr 2019 14:36:20 +0000 (UTC) Subject: Re: [PATCH v2 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock To: Alex Kogan , linux@armlinux.org.uk, peterz@infradead.org, mingo@redhat.com, will.deacon@arm.com, arnd@arndb.de, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, bp@alien8.de, hpa@zytor.com, x86@kernel.org Cc: steven.sistare@oracle.com, daniel.m.jordan@oracle.com, dave.dice@oracle.com, rahul.x.yadav@oracle.com References: <20190329152006.110370-1-alex.kogan@oracle.com> <20190329152006.110370-4-alex.kogan@oracle.com> From: Waiman Long Openpgp: preference=signencrypt Autocrypt: addr=longman@redhat.com; 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Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20190329152006.110370-4-alex.kogan@oracle.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Mon, 01 Apr 2019 14:36:22 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/29/2019 11:20 AM, Alex Kogan wrote: > In CNA, spinning threads are organized in two queues, a main queue for > threads running on the same node as the current lock holder, and a > secondary queue for threads running on other nodes. At the unlock time, > the lock holder scans the main queue looking for a thread running on > the same node. If found (call it thread T), all threads in the main queue > between the current lock holder and T are moved to the end of the > secondary queue, and the lock is passed to T. If such T is not found, the > lock is passed to the first node in the secondary queue. Finally, if the > secondary queue is empty, the lock is passed to the next thread in the > main queue. For more details, see https://arxiv.org/abs/1810.05600. > > Note that this variant of CNA may introduce starvation by continuously > passing the lock to threads running on the same node. This issue > will be addressed later in the series. > > Enabling CNA is controlled via a new configuration option > (NUMA_AWARE_SPINLOCKS), which is enabled by default if NUMA is enabled. > > Signed-off-by: Alex Kogan > Reviewed-by: Steve Sistare > --- > arch/x86/Kconfig | 14 +++ > include/asm-generic/qspinlock_types.h | 13 +++ > kernel/locking/mcs_spinlock.h | 10 ++ > kernel/locking/qspinlock.c | 29 +++++- > kernel/locking/qspinlock_cna.h | 173 ++++++++++++++++++++++++++++++++++ > 5 files changed, 236 insertions(+), 3 deletions(-) > create mode 100644 kernel/locking/qspinlock_cna.h > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 68261430fe6e..e70c39a901f2 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -1554,6 +1554,20 @@ config NUMA > > Otherwise, you should say N. > > +config NUMA_AWARE_SPINLOCKS > + bool "Numa-aware spinlocks" > + depends on NUMA > + default y > + help > + Introduce NUMA (Non Uniform Memory Access) awareness into > + the slow path of spinlocks. > + > + The kernel will try to keep the lock on the same node, > + thus reducing the number of remote cache misses, while > + trading some of the short term fairness for better performance. > + > + Say N if you want absolute first come first serve fairness. > + The patch that I am looking for is to have a separate numa_queued_spinlock_slowpath() that coexists with native_queued_spinlock_slowpath() and paravirt_queued_spinlock_slowpath(). At boot time, we select the most appropriate one for the system at hand. If you are going for the configuration option route, keep in mind that we optimize for the most common cases which are single-socket systems. Please default to "n" unless you can prove that your change won't regress performance for single-socket systems. 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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hAy30-0004AS-UK; Mon, 01 Apr 2019 14:36:26 +0000 Received: from mx1.redhat.com ([209.132.183.28]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1hAy2x-00049z-NL for linux-arm-kernel@lists.infradead.org; Mon, 01 Apr 2019 14:36:25 +0000 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5BF8D882F0; Mon, 1 Apr 2019 14:36:22 +0000 (UTC) Received: from llong.remote.csb (dhcp-17-19.bos.redhat.com [10.18.17.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4E9FA19C7C; Mon, 1 Apr 2019 14:36:20 +0000 (UTC) Subject: Re: [PATCH v2 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock To: Alex Kogan , linux@armlinux.org.uk, peterz@infradead.org, mingo@redhat.com, will.deacon@arm.com, arnd@arndb.de, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, bp@alien8.de, hpa@zytor.com, x86@kernel.org References: <20190329152006.110370-1-alex.kogan@oracle.com> <20190329152006.110370-4-alex.kogan@oracle.com> From: Waiman Long Openpgp: preference=signencrypt Autocrypt: addr=longman@redhat.com; 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Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20190329152006.110370-4-alex.kogan@oracle.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Mon, 01 Apr 2019 14:36:22 +0000 (UTC) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190401_073623_797359_9E573A0B X-CRM114-Status: GOOD ( 26.77 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: rahul.x.yadav@oracle.com, dave.dice@oracle.com, steven.sistare@oracle.com, daniel.m.jordan@oracle.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 03/29/2019 11:20 AM, Alex Kogan wrote: > In CNA, spinning threads are organized in two queues, a main queue for > threads running on the same node as the current lock holder, and a > secondary queue for threads running on other nodes. At the unlock time, > the lock holder scans the main queue looking for a thread running on > the same node. If found (call it thread T), all threads in the main queue > between the current lock holder and T are moved to the end of the > secondary queue, and the lock is passed to T. If such T is not found, the > lock is passed to the first node in the secondary queue. Finally, if the > secondary queue is empty, the lock is passed to the next thread in the > main queue. For more details, see https://arxiv.org/abs/1810.05600. > > Note that this variant of CNA may introduce starvation by continuously > passing the lock to threads running on the same node. This issue > will be addressed later in the series. > > Enabling CNA is controlled via a new configuration option > (NUMA_AWARE_SPINLOCKS), which is enabled by default if NUMA is enabled. > > Signed-off-by: Alex Kogan > Reviewed-by: Steve Sistare > --- > arch/x86/Kconfig | 14 +++ > include/asm-generic/qspinlock_types.h | 13 +++ > kernel/locking/mcs_spinlock.h | 10 ++ > kernel/locking/qspinlock.c | 29 +++++- > kernel/locking/qspinlock_cna.h | 173 ++++++++++++++++++++++++++++++++++ > 5 files changed, 236 insertions(+), 3 deletions(-) > create mode 100644 kernel/locking/qspinlock_cna.h > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 68261430fe6e..e70c39a901f2 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -1554,6 +1554,20 @@ config NUMA > > Otherwise, you should say N. > > +config NUMA_AWARE_SPINLOCKS > + bool "Numa-aware spinlocks" > + depends on NUMA > + default y > + help > + Introduce NUMA (Non Uniform Memory Access) awareness into > + the slow path of spinlocks. > + > + The kernel will try to keep the lock on the same node, > + thus reducing the number of remote cache misses, while > + trading some of the short term fairness for better performance. > + > + Say N if you want absolute first come first serve fairness. > + The patch that I am looking for is to have a separate numa_queued_spinlock_slowpath() that coexists with native_queued_spinlock_slowpath() and paravirt_queued_spinlock_slowpath(). At boot time, we select the most appropriate one for the system at hand. If you are going for the configuration option route, keep in mind that we optimize for the most common cases which are single-socket systems. Please default to "n" unless you can prove that your change won't regress performance for single-socket systems. Cheers, Longman _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel