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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 55242C43334 for ; Wed, 6 Jul 2022 13:40:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232384AbiGFNkx (ORCPT ); Wed, 6 Jul 2022 09:40:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40230 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229757AbiGFNku (ORCPT ); Wed, 6 Jul 2022 09:40:50 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BCE652317C; Wed, 6 Jul 2022 06:40:48 -0700 (PDT) Received: from fraeml735-chm.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4LdLG35gX0z689K5; Wed, 6 Jul 2022 21:38:03 +0800 (CST) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by fraeml735-chm.china.huawei.com (10.206.15.216) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Wed, 6 Jul 2022 15:40:46 +0200 Received: from [10.126.171.66] (10.126.171.66) 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; Wed, 6 Jul 2022 14:40:45 +0100 Message-ID: Date: Wed, 6 Jul 2022 14:40:44 +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 v5 0/5] DMA mapping changes for SCSI core To: , , , , , , , CC: , , , , , , References: <1656590892-42307-1-git-send-email-john.garry@huawei.com> From: John Garry In-Reply-To: <1656590892-42307-1-git-send-email-john.garry@huawei.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.126.171.66] X-ClientProxiedBy: lhreml732-chm.china.huawei.com (10.201.108.83) 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 30/06/2022 13:08, John Garry wrote: Hi Christoph, Can you please consider picking up this series? A few things to note beforehand: - I changed to only apply the mapping limit to SAS hosts in this version. I would need a fresh ack from Martin for those SCSI parts, but wanted to make sure you were ok with it. - Damien had some doubt on updating the shost max_sectors as opposed to the per-request queue default, but I think he's ok with it - see patch 4/5 Thanks, John > As reported in [0], DMA mappings whose size exceeds the IOMMU IOVA caching > limit may see a big performance hit. > > This series introduces a new DMA mapping API, dma_opt_mapping_size(), so > that drivers may know this limit when performance is a factor in the > mapping. > > The SCSI SAS transport code is modified only to use this limit. For now I > did not want to touch other hosts as I have a concern that this change > could cause a performance regression. > > I also added a patch for libata-scsi as it does not currently honour the > shost max_sectors limit. > > [0]https://lore.kernel.org/linux-iommu/20210129092120.1482-1-thunder.leizhen@huawei.com/ > > Changes since v4: > - tweak libata and other patch titles > - Add Robin's tag (thanks!) > - Clarify description of new DMA mapping API