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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 67F20C388F7 for ; Tue, 10 Nov 2020 09:41:32 +0000 (UTC) Received: from silver.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 9059820781 for ; Tue, 10 Nov 2020 09:41:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9059820781 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 silver.osuosl.org (Postfix) with ESMTP id F03B020C92; Tue, 10 Nov 2020 09:41:30 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id JcgzdOdCrYoh; Tue, 10 Nov 2020 09:41:30 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by silver.osuosl.org (Postfix) with ESMTP id 59404204BE; Tue, 10 Nov 2020 09:41:30 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 4D1B1C088B; Tue, 10 Nov 2020 09:41:30 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id EAF3BC016F for ; Tue, 10 Nov 2020 09:41:28 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id D7B812050D for ; Tue, 10 Nov 2020 09:41:28 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id xyD0qGfXU4gB for ; Tue, 10 Nov 2020 09:41:27 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by silver.osuosl.org (Postfix) with ESMTPS id 91CF8204BE for ; Tue, 10 Nov 2020 09:41:27 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 9BE796736F; Tue, 10 Nov 2020 10:41:23 +0100 (CET) Date: Tue, 10 Nov 2020 10:41:23 +0100 From: Christoph Hellwig To: Ricardo Ribalda Subject: Re: [PATCH 8/8] WIP: add a dma_alloc_contiguous API Message-ID: <20201110094123.GA25672@lst.de> References: <20200930160917.1234225-1-hch@lst.de> <20200930160917.1234225-9-hch@lst.de> <20201110092506.GA24469@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Cc: Linux Media Mailing List , Linux Doc Mailing List , Linux Kernel Mailing List , "list@263.net:IOMMU DRIVERS , Joerg Roedel , " , Mauro Carvalho Chehab , Robin Murphy , Christoph Hellwig 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 Tue, Nov 10, 2020 at 10:33:05AM +0100, Ricardo Ribalda wrote: > Also FYI, I managed to boot an ARM device with that tree. But I could > not test the uvc driver (it was a remote device with no usb device > attached) > > Hopefully I will be able to test it for real this week. > > Any suggestions for how to measure performance difference? I have to admit I don't know at all how uvc works. But the main problem with dma_alloc_coherent is that all access is uncached. So anything that does larger and/or many data transfers to and from it will be glacially slow. With the dma streaming API we still have to pay for cache flushes, but only before and after the transfers, and in many cases in a somewhat optimized fashion. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu