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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 4116BC4338F for ; Wed, 28 Jul 2021 10:38:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2AC3A60F9B for ; Wed, 28 Jul 2021 10:38:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234186AbhG1Kiu (ORCPT ); Wed, 28 Jul 2021 06:38:50 -0400 Received: from frasgout.his.huawei.com ([185.176.79.56]:3510 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236027AbhG1Kio (ORCPT ); Wed, 28 Jul 2021 06:38:44 -0400 Received: from fraeml702-chm.china.huawei.com (unknown [172.18.147.200]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4GZVFj46N2z6L9kY; Wed, 28 Jul 2021 18:26:49 +0800 (CST) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by fraeml702-chm.china.huawei.com (10.206.15.51) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Wed, 28 Jul 2021 12:38:41 +0200 Received: from [10.47.27.80] (10.47.27.80) 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 15.1.2176.2; Wed, 28 Jul 2021 11:38:41 +0100 From: John Garry Subject: Re: [bug report] iommu_dma_unmap_sg() is very slow then running IO from remote numa node To: Ming Lei CC: Robin Murphy , , , , "Will Deacon" , References: <74537f9c-af5f-cd84-60ab-49ca6220310e@huawei.com> <9c929985-4fcb-e65d-0265-34c820b770ea@huawei.com> <0adbe03b-ce26-e4d3-3425-d967bc436ef5@arm.com> <6ceab844-465f-3bf3-1809-5df1f1dbbc5c@huawei.com> Message-ID: Date: Wed, 28 Jul 2021 11:38:18 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.47.27.80] X-ClientProxiedBy: lhreml706-chm.china.huawei.com (10.201.108.55) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 28/07/2021 02:32, Ming Lei wrote: > On Mon, Jul 26, 2021 at 3:51 PM John Garry wrote: >> On 23/07/2021 11:21, Ming Lei wrote: >>>> Thanks, I was also going to suggest the latter, since it's what >>>> arm_smmu_cmdq_issue_cmdlist() does with IRQs masked that should be most >>>> indicative of where the slowness most likely stems from. >>> The improvement from 'iommu.strict=0' is very small: >>> >> Have you tried turning off the IOMMU to ensure that this is really just >> an IOMMU problem? >> >> You can try setting CONFIG_ARM_SMMU_V3=n in the defconfig or passing >> cmdline param iommu.passthrough=1 to bypass the the SMMU (equivalent to >> disabling for kernel drivers). > Bypassing SMMU via iommu.passthrough=1 basically doesn't make a difference > on this issue. A ~90% throughput drop still seems to me to be too high to be a software issue. More so since I don't see similar on my system. And that throughput drop does not lead to a total CPU usage drop, from the fio log. Do you know if anyone has run memory benchmark tests on this board to find out NUMA effect? I think lmbench or stream could be used for this. Testing network performance in an equivalent fashion to storage could also be an idea. Thanks, John > > And from fio log, submission latency is good, but completion latency > is pretty bad, > and maybe it is something that writing to PCI memory isn't committed to HW in > time?