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,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 E7BEEC433E0 for ; Fri, 19 Mar 2021 13:40:55 +0000 (UTC) Received: from smtp3.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 40C036023B for ; Fri, 19 Mar 2021 13:40:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 40C036023B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id EA78960714; Fri, 19 Mar 2021 13:40:54 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id pgt-dJY-sAw6; Fri, 19 Mar 2021 13:40:54 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp3.osuosl.org (Postfix) with ESMTP id DFC05605D1; Fri, 19 Mar 2021 13:40:53 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id C683DC000A; Fri, 19 Mar 2021 13:40:53 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [IPv6:2605:bc80:3010::138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 1685FC0001 for ; Fri, 19 Mar 2021 13:40:52 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 04A8B8350D for ; Fri, 19 Mar 2021 13:40:52 +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 LsReVYvwOXub for ; Fri, 19 Mar 2021 13:40:50 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.8.0 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by smtp1.osuosl.org (Postfix) with ESMTPS id C487D83508 for ; Fri, 19 Mar 2021 13:40:50 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 6A6C368BFE; Fri, 19 Mar 2021 14:40:47 +0100 (CET) Date: Fri, 19 Mar 2021 14:40:47 +0100 From: Christoph Hellwig To: John Garry Subject: Re: [PATCH 0/6] dma mapping/iommu: Allow IOMMU IOVA rcache range to be configured Message-ID: <20210319134047.GA5729@lst.de> References: <1616160348-29451-1-git-send-email-john.garry@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1616160348-29451-1-git-send-email-john.garry@huawei.com> User-Agent: Mutt/1.5.17 (2007-11-01) Cc: linux-scsi@vger.kernel.org, martin.petersen@oracle.com, robin.murphy@arm.com, linuxarm@huawei.com, linux-kernel@vger.kernel.org, hch@lst.de, iommu@lists.linux-foundation.org, will@kernel.org, jejb@linux.ibm.com 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Fri, Mar 19, 2021 at 09:25:42PM +0800, John Garry wrote: > For streaming DMA mappings involving an IOMMU and whose IOVA len regularly > exceeds the IOVA rcache upper limit (meaning that they are not cached), > performance can be reduced. > > This is much more pronounced from commit 4e89dce72521 ("iommu/iova: Retry > from last rb tree node if iova search fails"), as discussed at [0]. > > IOVAs which cannot be cached are highly involved in the IOVA aging issue, > as discussed at [1]. I'm confused. If this a limit in the IOVA allocator, dma-iommu should be able to just not grow the allocation so larger without help from the driver. If contrary to the above description it is device-specific, the driver could simply use dma_get_max_seg_size(). _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu