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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 BC63EC433DF for ; Wed, 8 Jul 2020 13:04:22 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 86F5620658 for ; Wed, 8 Jul 2020 13:04:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="g8SItGxu" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 86F5620658 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+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=merlin.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:References: To:Subject:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=cH26LBldLYo0pmoVY6G6cwhC4M5GbOVSpbNcco+w1Hs=; b=g8SItGxuJX2wPMC5RDHj7lOaA tgkcSnla3zRabRrehIG5rvNrAwX4G9a9X4MxOdDDjbqsAFaB50GVGiq4yzrLHamgfJxG0Hnp5+Bf/ ewnmcB4dO4wXA7TkcumNTHoAx32N3g4ef+mmqLb2bWBzqKbHctaDD+Kgeqr3TPwSnuUbuQE0NwFtK S26OoAcWXxcwBdkiDg6Us17V9v8QjoNqav86vk/e47hyEZbcMlsKIYmZF2w9BhrVHk9QFfpenlbRc kQoNWzqj93xUcfITt4jRICfNtpPXWkJOW0FmdGxR9SQWovZLJP9bjchbf+htU0d8ExnzAAWAOD6ol qGSp0pcZg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jt9is-00045t-TO; Wed, 08 Jul 2020 13:02:50 +0000 Received: from lhrrgout.huawei.com ([185.176.76.210] helo=huawei.com) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jt9iq-00043s-QG for linux-arm-kernel@lists.infradead.org; Wed, 08 Jul 2020 13:02:49 +0000 Received: from lhreml724-chm.china.huawei.com (unknown [172.18.7.106]) by Forcepoint Email with ESMTP id 6303BD8543793A5CD515; Wed, 8 Jul 2020 14:02:36 +0100 (IST) Received: from [127.0.0.1] (10.210.171.111) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.1913.5; Wed, 8 Jul 2020 14:02:35 +0100 From: John Garry Subject: Re: [PATCH 0/4] iommu/arm-smmu-v3: Improve cmdq lock efficiency To: , References: <1592846920-45338-1-git-send-email-john.garry@huawei.com> Message-ID: Date: Wed, 8 Jul 2020 14:00:54 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: <1592846920-45338-1-git-send-email-john.garry@huawei.com> Content-Language: en-US X-Originating-IP: [10.210.171.111] X-ClientProxiedBy: lhreml709-chm.china.huawei.com (10.201.108.58) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200708_090248_972290_5A47741A X-CRM114-Status: GOOD ( 14.67 ) 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: trivial@kernel.org, maz@kernel.org, joro@8bytes.org, linuxarm@huawei.com, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 22/06/2020 18:28, John Garry wrote: Hi, Can you guys let me know if this is on the radar at all? I have been talking about this performance issue since Jan, and not getting anything really. thanks > As mentioned in [0], the CPU may consume many cycles processing > arm_smmu_cmdq_issue_cmdlist(). One issue we find is the cmpxchg() loop to > get space on the queue takes approx 25% of the cycles for this function. > > This series removes that cmpxchg(). > > For my NVMe test with 3x NVMe SSDs, I'm getting a ~24% throughput > increase: > Before: 1310 IOPs > After: 1630 IOPs > > I also have a test harness to check the rate of DMA map+unmaps we can > achieve: > > CPU count 32 64 128 > Before: 63187 19418 10169 > After: 93287 44789 15862 > > (unit is map+unmaps per CPU per second) > > [0] https://lore.kernel.org/linux-iommu/B926444035E5E2439431908E3842AFD24B86DB@DGGEMI525-MBS.china.huawei.com/T/#ma02e301c38c3e94b7725e685757c27e39c7cbde3 > > John Garry (4): > iommu/arm-smmu-v3: Fix trivial typo > iommu/arm-smmu-v3: Calculate bits for prod and owner > iommu/arm-smmu-v3: Always issue a CMD_SYNC per batch > iommu/arm-smmu-v3: Remove cmpxchg() in arm_smmu_cmdq_issue_cmdlist() > > drivers/iommu/arm-smmu-v3.c | 233 +++++++++++++++++++++++------------- > 1 file changed, 151 insertions(+), 82 deletions(-) > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel