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,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 CC654C43381 for ; Mon, 18 Feb 2019 14:59:02 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 994F92173C for ; Mon, 18 Feb 2019 14:59:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="eIaRTiiO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 994F92173C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=negFrzDjy4ZQsWiKPOuCMwPecotOEs5Rz3kaZDZvIC0=; b=eIaRTiiOdIG6GN Mk6p/wYouX/6b++wMMj/KMSvgJ6Zje7dqYsow3d76wMQ4EimALWy7tcMySG5PKVweN5kulYILMRyG MaUzb9zrjwAEk1Y1sL2zYZful7N0EmhKcEYN9pBBidgQc6G6lNC/4zP6tONRYGPFWTVTMjMagHMy2 jgMIM+9AV9rTSIQ53rZgZwz3lB/oyzEUP71r+8eOnByXoKYm8L0LhfgjCUV+ap36jRrwS4QTHC0XU tRSa2WSSTEuOBN9jdioJ0aj0bzACwNKxF/1cxpeQAKIjs8+xChqGcNMT8E0Rwti7m+E0nxsdEShql VyF0l/UEWw7UHTp5fHAw==; 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 1gvkNl-0001Qp-Au; Mon, 18 Feb 2019 14:58:57 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gvkNR-0001PN-PJ; Mon, 18 Feb 2019 14:58:53 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 7B193A78; Mon, 18 Feb 2019 06:58:30 -0800 (PST) Received: from fuggles.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7F1D53F675; Mon, 18 Feb 2019 06:58:25 -0800 (PST) Date: Mon, 18 Feb 2019 14:58:20 +0000 From: Will Deacon To: Waiman Long Subject: Re: [PATCH v4 0/3] locking/rwsem: Rwsem rearchitecture part 0 Message-ID: <20190218145820.GA16091@fuggles.cambridge.arm.com> References: <1550095217-12047-1-git-send-email-longman@redhat.com> <20190214103715.GI32494@hirez.programming.kicks-ass.net> <20190215184056.GC15084@fuggles.cambridge.arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.1+86 (6f28e57d73f2) () X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190218_065852_087956_15D3FE5C X-CRM114-Status: GOOD ( 19.98 ) 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: linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Peter Zijlstra , linux-mips@vger.kernel.org, "H. Peter Anvin" , sparclinux@vger.kernel.org, linux-riscv@lists.infradead.org, linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, Davidlohr Bueso , linux-c6x-dev@linux-c6x.org, linux-hexagon@vger.kernel.org, x86@kernel.org, Ingo Molnar , uclinux-h8-devel@lists.sourceforge.jp, linux-xtensa@linux-xtensa.org, Arnd Bergmann , linux-um@lists.infradead.org, linux-m68k@lists.linux-m68k.org, openrisc@lists.librecores.org, Borislav Petkov , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Tim Chen , linux-parisc@vger.kernel.org, Linus Torvalds , linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, nios2-dev@lists.rocketboards.org, Andrew Morton , linuxppc-dev@lists.ozlabs.org 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 Fri, Feb 15, 2019 at 01:58:34PM -0500, Waiman Long wrote: > On 02/15/2019 01:40 PM, Will Deacon wrote: > > On Thu, Feb 14, 2019 at 11:37:15AM +0100, Peter Zijlstra wrote: > >> On Wed, Feb 13, 2019 at 05:00:14PM -0500, Waiman Long wrote: > >>> v4: > >>> - Remove rwsem-spinlock.c and make all archs use rwsem-xadd.c. > >>> > >>> v3: > >>> - Optimize __down_read_trylock() for the uncontended case as suggested > >>> by Linus. > >>> > >>> v2: > >>> - Add patch 2 to optimize __down_read_trylock() as suggested by PeterZ. > >>> - Update performance test data in patch 1. > >>> > >>> The goal of this patchset is to remove the architecture specific files > >>> for rwsem-xadd to make it easer to add enhancements in the later rwsem > >>> patches. It also removes the legacy rwsem-spinlock.c file and make all > >>> the architectures use one single implementation of rwsem - rwsem-xadd.c. > >>> > >>> Waiman Long (3): > >>> locking/rwsem: Remove arch specific rwsem files > >>> locking/rwsem: Remove rwsem-spinlock.c & use rwsem-xadd.c for all > >>> archs > >>> locking/rwsem: Optimize down_read_trylock() > >> Acked-by: Peter Zijlstra (Intel) > >> > >> with the caveat that I'm happy to exchange patch 3 back to my earlier > >> suggestion in case Will expesses concerns wrt the ARM64 performance of > >> Linus' suggestion. > > Right, the current proposal doesn't work well for us, unfortunately. Which > > was your earlier suggestion? > > > > Will > > In my posting yesterday, I showed that most of the trylocks done were > actually uncontended. Assuming that pattern hold for the most of the > workloads, it will not that bad after all. That's fair enough; if you're going to sit in a tight trylock() loop like the benchmark does, then you're much better off just calling lock() if you care at all about scalability. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel