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=-2.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,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 AD297C3A5A1 for ; Wed, 28 Aug 2019 09:04:19 +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 836AF214DA for ; Wed, 28 Aug 2019 09:04:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="fNfWYExT" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 836AF214DA 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=4B8d3PgCrWNHvp8cReWhCloXxGkgwO1Co1zPqGF7um4=; b=fNfWYExTKGxKGr RnmQ4q99X9J968m8aH3WbiVv9+IoWRHGacNKbtTn+fXHVPquxqcSEBgCRN3anl9oIRyVPCGvt5Ce8 bHwq1kLSuQveJjpqt83utdLj+ueI0U8LoUzKlWWLjuy3Tggx2HD5KXu6aJZC9kDTzygTxJfcaB+7Z zSy306JP/9cDxAbHHbddkPpHcvDuGpCPfIwJgm8HItdlr1GvigC06+NLC/52m4xO5QObyIVetvXGK gLy5ccuZZUlpwO53/HO43sDVfyFrpeMJH2KvB1j3rhGwE+2uRFxYIrNqUE690jpVIuRxWWj664xq/ 6iZ1w9GJputmiy71WScA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1i2tsF-0006w1-LV; Wed, 28 Aug 2019 09:04:15 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1i2tsD-0006ve-GW for linux-arm-kernel@lists.infradead.org; Wed, 28 Aug 2019 09:04:14 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id BD018337; Wed, 28 Aug 2019 02:04:12 -0700 (PDT) Received: from localhost (unknown [10.37.6.20]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3E41E3F59C; Wed, 28 Aug 2019 02:04:12 -0700 (PDT) Date: Wed, 28 Aug 2019 10:04:10 +0100 From: Andrew Murray To: Will Deacon Subject: Re: [PATCH v3 0/5] arm64: avoid out-of-line ll/sc atomics Message-ID: <20190828090410.GS14582@e119886-lin.cambridge.arm.com> References: <20190812143625.42745-1-andrew.murray@arm.com> <20190827164944.qxk32uas7hx5pjgz@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190827164944.qxk32uas7hx5pjgz@willie-the-truck> User-Agent: Mutt/1.10.1+81 (426a6c1) (2018-08-26) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190828_020413_595249_DE6420B9 X-CRM114-Status: GOOD ( 18.34 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Peter Zijlstra , Catalin Marinas , Boqun Feng , Will Deacon , Ard.Biesheuvel@arm.com, linux-arm-kernel@lists.infradead.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 Tue, Aug 27, 2019 at 05:49:45PM +0100, Will Deacon wrote: > Hi Andrew, > > On Mon, Aug 12, 2019 at 03:36:20PM +0100, Andrew Murray wrote: > > When building for LSE atomics (CONFIG_ARM64_LSE_ATOMICS), if the hardware > > or toolchain doesn't support it the existing code will fallback to ll/sc > > atomics. It achieves this by branching from inline assembly to a function > > that is built with specical compile flags. Further this results in the > > clobbering of registers even when the fallback isn't used increasing > > register pressure. > > > > Let's improve this by providing inline implementatins of both LSE and > > ll/sc and use a static key to select between them. This allows for the > > compiler to generate better atomics code. > > > > Whilst it may be difficult to understand the performance impact, we gain > > improved code readability, ability to use Clang, and improved backtrace > > reliability. > > > > Build and boot tested, along with atomic_64_test. > > I think this series is really close now and I was hoping to get something > queued for 5.4. Would you be able to respin, addressing Mark's comments > please? It would be a shame for this to miss another release. Sure, I'm working on this now. Thanks, Andrew Murray > > Thanks, > > Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel