From patchwork Mon Jun 27 15:25:20 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Garry X-Patchwork-Id: 12896790 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 60177CCA481 for ; Mon, 27 Jun 2022 15:33:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235355AbiF0PdD (ORCPT ); Mon, 27 Jun 2022 11:33:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52396 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236506AbiF0PcH (ORCPT ); Mon, 27 Jun 2022 11:32:07 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2BD201A06B; Mon, 27 Jun 2022 08:31:49 -0700 (PDT) Received: from fraeml741-chm.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4LWs6q2Lcmz6H8F0; Mon, 27 Jun 2022 23:27:47 +0800 (CST) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by fraeml741-chm.china.huawei.com (10.206.15.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Mon, 27 Jun 2022 17:31:47 +0200 Received: from localhost.localdomain (10.69.192.58) 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; Mon, 27 Jun 2022 16:31:43 +0100 From: John Garry To: , , , , , , , CC: , , , , , , , John Garry Subject: [PATCH v4 4/5] scsi: scsi_transport_sas: Cap shost max_sectors according to DMA optimal mapping limit Date: Mon, 27 Jun 2022 23:25:20 +0800 Message-ID: <1656343521-62897-5-git-send-email-john.garry@huawei.com> X-Mailer: git-send-email 2.8.1 In-Reply-To: <1656343521-62897-1-git-send-email-john.garry@huawei.com> References: <1656343521-62897-1-git-send-email-john.garry@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.69.192.58] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org Streaming DMA mappings may be considerably slower when mappings go through an IOMMU and the total mapping length is somewhat long. This is because the IOMMU IOVA code allocates and free an IOVA for each mapping, which may affect performance. For performance reasons set the request queue max_sectors from dma_opt_mapping_size(), which knows this mapping limit. Signed-off-by: John Garry --- drivers/scsi/scsi_transport_sas.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/scsi/scsi_transport_sas.c b/drivers/scsi/scsi_transport_sas.c index 12bff64dade6..1b45248748e0 100644 --- a/drivers/scsi/scsi_transport_sas.c +++ b/drivers/scsi/scsi_transport_sas.c @@ -225,6 +225,7 @@ static int sas_host_setup(struct transport_container *tc, struct device *dev, { struct Scsi_Host *shost = dev_to_shost(dev); struct sas_host_attrs *sas_host = to_sas_host_attrs(shost); + struct device *dma_dev = shost->dma_dev; INIT_LIST_HEAD(&sas_host->rphy_list); mutex_init(&sas_host->lock); @@ -236,6 +237,11 @@ static int sas_host_setup(struct transport_container *tc, struct device *dev, dev_printk(KERN_ERR, dev, "fail to a bsg device %d\n", shost->host_no); + if (dma_dev) { + shost->max_sectors = min_t(unsigned int, shost->max_sectors, + dma_opt_mapping_size(dma_dev) >> SECTOR_SHIFT); + } + return 0; }