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 Received: from smtp1.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 smtp.lore.kernel.org (Postfix) with ESMTPS id D9FC4C43334 for ; Thu, 9 Jun 2022 08:00:59 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 7F94983F7D; Thu, 9 Jun 2022 08:00:59 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 9oYZWoalzYTX; Thu, 9 Jun 2022 08:00:58 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp1.osuosl.org (Postfix) with ESMTPS id 6958E83E93; Thu, 9 Jun 2022 08:00:58 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 44121C0032; Thu, 9 Jun 2022 08:00:58 +0000 (UTC) Received: from smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id 4BD44C002D for ; Thu, 9 Jun 2022 08:00:57 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id 2CDCD41B8C for ; Thu, 9 Jun 2022 08:00:57 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id sWqUKubl6JZW for ; Thu, 9 Jun 2022 08:00:56 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by smtp4.osuosl.org (Postfix) with ESMTPS id CABCF41B72 for ; Thu, 9 Jun 2022 08:00:55 +0000 (UTC) Received: from fraeml743-chm.china.huawei.com (unknown [172.18.147.207]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4LJbxw3Jf7z6881w; Thu, 9 Jun 2022 15:56:04 +0800 (CST) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by fraeml743-chm.china.huawei.com (10.206.15.224) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 9 Jun 2022 10:00:52 +0200 Received: from [10.47.88.201] (10.47.88.201) 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 15.1.2375.24; Thu, 9 Jun 2022 09:00:51 +0100 Message-ID: <5b214e95-dd95-551a-496e-a2139a74e8eb@huawei.com> Date: Thu, 9 Jun 2022 09:00:50 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.6.1 Subject: Re: [PATCH v3 3/4] scsi: core: Cap shost max_sectors according to DMA optimum mapping limits To: Bart Van Assche , , , , , , , , References: <1654507822-168026-1-git-send-email-john.garry@huawei.com> <1654507822-168026-4-git-send-email-john.garry@huawei.com> <31417477-953d-283e-808e-cf8701e820a8@huawei.com> In-Reply-To: X-Originating-IP: [10.47.88.201] X-ClientProxiedBy: lhreml727-chm.china.huawei.com (10.201.108.78) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Cc: linux-scsi@vger.kernel.org, linux-doc@vger.kernel.org, liyihang6@hisilicon.com, linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org, iommu@lists.linux-foundation.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: , From: John Garry via iommu Reply-To: John Garry Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On 08/06/2022 22:07, Bart Van Assche wrote: > On 6/8/22 10:50, John Garry wrote: >> Please note that this limit only applies if we have an IOMMU enabled >> for the scsi host dma device. Otherwise we are limited by dma direct >> or swiotlb max mapping size, as before. > > SCSI host bus adapters that support 64-bit DMA may support much larger > transfer sizes than 128 KiB. Indeed, and that is my problem today, as my storage controller is generating DMA mapping lengths which exceeds 128K and they slow everything down. If you say that SRP enjoys best peformance with larger transfers then can you please test this with an IOMMU enabled (iommu group type DMA or DMA-FQ)? Thanks, John _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu