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=-6.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,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 5B7BAC4338F for ; Thu, 5 Aug 2021 11:23:02 +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 1AC7460EE5 for ; Thu, 5 Aug 2021 11:23:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 1AC7460EE5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc: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=mIY6viWeM1AtmdKO2jy/BT/M5rG8RN/MRs5FvlnscyA=; b=hOBLh/2f518EWo E2nkZjJtwESqIEanSF8L2Ci0oJQIDnn2M8zMEERPIbRd5/Ck2QSmyrfjOinLFWzBuIRfwkmwtBZc6 bQ1+kSaKMEoHTDIM2ONOTifTMwHlmFek7tOGeRCQRBZr30Ua0nU1077RbBJGGlLzNQIG5V3JlzYJl /1oujyMa9L70teG0uqwL1sJxHBm/aPEMJ8QeG14DVE/Pf7lCfYgk1hh3v0QgqTsQ2iFm0Y+5YVnQq 1sod2EDJOjepWFxvF8x5L6KO92T5DGxR309R0HRql15XqGToKL1sBTLfvPpG33pdPYXAUYmjxLBqJ ob3ACauPg9BjV6U3qXUQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mBbRE-009Fqw-FT; Thu, 05 Aug 2021 11:21:24 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mBbRB-009FqJ-0a for linux-arm-kernel@lists.infradead.org; Thu, 05 Aug 2021 11:21:22 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 514BA60E52; Thu, 5 Aug 2021 11:21:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1628162479; bh=VFjPtC9UhoM5gV86KddMtIiMoUfeT0FE4dm7xQ3W6Cc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MG0aCq2J0TAoC4bp0QExr9x8nHi3ql8ui5whAPq7792IAnLdi7gSysxE6TMaT6Vjc CobHs41s8ZGRZgRFlwEzqxtjqyrimdIFgde5Ir4GX/6KAgLbV1n7YCtfpBU3arbOry Ulq3puR70zHNAwVQXxOMuWh/SBagtDDSid7BOav1SvK54ArCtJvuG4Jx+og+oiYWxb 7vzVlx+cpM+VDVpLidQcgiTTj9lllSlrafW6UJMhB/iaV3il7HMO0esb3c43RLFuhv nIETmcSfEzAJESa4I7JAwy5pe7otuCqY4p5wZDfZ5MezC79T/QSBOOq8IAf4njOP+w qrfPLNDU1J26w== Date: Thu, 5 Aug 2021 12:21:14 +0100 From: Will Deacon To: John Garry Cc: robin.murphy@arm.com, joro@8bytes.org, linux-arm-kernel@lists.infradead.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linuxarm@huawei.com Subject: Re: [PATCH] iommu/arm-smmu-v3: Remove some unneeded init in arm_smmu_cmdq_issue_cmdlist() Message-ID: <20210805112114.GA1029@willie-the-truck> References: <1624293394-202509-1-git-send-email-john.garry@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210805_042121_113637_F60066FD X-CRM114-Status: GOOD ( 14.69 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Aug 05, 2021 at 11:22:15AM +0100, John Garry wrote: > On 21/06/2021 17:36, John Garry wrote: > > Members of struct "llq" will be zero-inited, apart from member max_n_shift. > > But we write llq.val straight after the init, so it was pointless to zero > > init those other members. As such, separately init member max_n_shift > > only. > > > > In addition, struct "head" is initialised to "llq" only so that member > > max_n_shift is set. But that member is never referenced for "head", so > > remove any init there. > > > > Removing these initializations is seen as a small performance optimisation, > > as this code is (very) hot path. > > > > Hi Will, > > Any chance you can pick up this small optimisation? Yup! I've actually queued it locally, but I may end up asking Joerg to take it directly depending on what else I queue for 5.15. So far, most of the SMMU stuff is all part of wider refactorings. Cheers, Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel