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=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 D721BC433E0 for ; Wed, 8 Jul 2020 13:02:45 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (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 A20FF20658 for ; Wed, 8 Jul 2020 13:02:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A20FF20658 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id 5AA2387799; Wed, 8 Jul 2020 13:02:45 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 3icwMjy3mUch; Wed, 8 Jul 2020 13:02:43 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by whitealder.osuosl.org (Postfix) with ESMTP id 86E318766A; Wed, 8 Jul 2020 13:02:43 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 6EFCCC077B; Wed, 8 Jul 2020 13:02:43 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 9A748C016F for ; Wed, 8 Jul 2020 13:02:41 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 967A78948F for ; Wed, 8 Jul 2020 13:02:41 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id bsgi2g6LNFKy for ; Wed, 8 Jul 2020 13:02:40 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from huawei.com (lhrrgout.huawei.com [185.176.76.210]) by hemlock.osuosl.org (Postfix) with ESMTPS id 883F68946D for ; Wed, 8 Jul 2020 13:02:40 +0000 (UTC) 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 Cc: trivial@kernel.org, maz@kernel.org, linuxarm@huawei.com, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" 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(-) > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu