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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 34364C432BE for ; Tue, 10 Aug 2021 09:37:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1CC8661076 for ; Tue, 10 Aug 2021 09:37:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239208AbhHJJhr (ORCPT ); Tue, 10 Aug 2021 05:37:47 -0400 Received: from frasgout.his.huawei.com ([185.176.79.56]:3621 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238140AbhHJJhq (ORCPT ); Tue, 10 Aug 2021 05:37:46 -0400 Received: from fraeml740-chm.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4GkSX12Jrkz6C9JD; Tue, 10 Aug 2021 17:36:49 +0800 (CST) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by fraeml740-chm.china.huawei.com (10.206.15.221) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.8; Tue, 10 Aug 2021 11:37:22 +0200 Received: from [10.47.80.4] (10.47.80.4) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Tue, 10 Aug 2021 10:37:21 +0100 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: <9c929985-4fcb-e65d-0265-34c820b770ea@huawei.com> <0adbe03b-ce26-e4d3-3425-d967bc436ef5@arm.com> <6ceab844-465f-3bf3-1809-5df1f1dbbc5c@huawei.com> From: John Garry Message-ID: Date: Tue, 10 Aug 2021 10:36:47 +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: [10.47.80.4] X-ClientProxiedBy: lhreml712-chm.china.huawei.com (10.201.108.63) 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 16:17, Ming Lei wrote: >>>> 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. > https://lore.kernel.org/lkml/YOhbc5C47IzC893B@T590/ Hi Ming, Out of curiosity, did you investigate this topic any further? And you also asked about my results earlier: On 22/07/2021 16:54, Ming Lei wrote: >> [ 52.035895] nvme 0000:81:00.0: Adding to iommu group 5 >> [ 52.047732] nvme nvme0: pci function 0000:81:00.0 >> [ 52.067216] nvme nvme0: 22/0/2 default/read/poll queues >> [ 52.087318] nvme0n1: p1 >> >> So I get these results: >> cpu0 335K >> cpu32 346K >> cpu64 300K >> cpu96 300K >> >> So still not massive changes. > In your last email, the results are the following with irq mode io_uring: > > cpu0 497K > cpu4 307K > cpu32 566K > cpu64 488K > cpu96 508K > > So looks you get much worse result with real io_polling? > Would the expectation be that at least I get the same performance with io_polling here? Anything else to try which you can suggest to investigate this lower performance? Thanks, John