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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29BF2C433FE for ; Tue, 8 Nov 2022 10:03:38 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 968EE6B0071; Tue, 8 Nov 2022 05:03:37 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 916C06B0073; Tue, 8 Nov 2022 05:03:37 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 805846B0074; Tue, 8 Nov 2022 05:03:37 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 7187B6B0071 for ; Tue, 8 Nov 2022 05:03:37 -0500 (EST) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 47BE41C6A62 for ; Tue, 8 Nov 2022 10:03:37 +0000 (UTC) X-FDA: 80109838074.19.A6CF629 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by imf30.hostedemail.com (Postfix) with ESMTP id 5800F80008 for ; Tue, 8 Nov 2022 10:03:36 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 473A268AFE; Tue, 8 Nov 2022 11:03:31 +0100 (CET) Date: Tue, 8 Nov 2022 11:03:31 +0100 From: Christoph Hellwig To: Catalin Marinas Cc: Robin Murphy , Linus Torvalds , Arnd Bergmann , Christoph Hellwig , Greg Kroah-Hartman , Will Deacon , Marc Zyngier , Andrew Morton , Herbert Xu , Ard Biesheuvel , Isaac Manjarres , Saravana Kannan , Alasdair Kergon , Daniel Vetter , Joerg Roedel , Mark Brown , Mike Snitzer , "Rafael J. Wysocki" , linux-mm@kvack.org, iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org, agraf@csgraf.de Subject: Re: [PATCH v3 13/13] dma: arm64: Add CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC and enable it for arm64 Message-ID: <20221108100331.GA31944@lst.de> References: <20221106220143.2129263-1-catalin.marinas@arm.com> <20221106220143.2129263-14-catalin.marinas@arm.com> <6e846f75-b330-9523-4356-41d5f9e48f12@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=none; spf=none (imf30.hostedemail.com: domain of hch@lst.de has no SPF policy when checking 213.95.11.211) smtp.mailfrom=hch@lst.de; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667901816; a=rsa-sha256; cv=none; b=TkEbljf1o9wy9/SlrpJUjzfuet96pTkGRz2gwFQS1nzxlQmxEIDFPfoc8qaTS7AhdGBJou cjJc0MbcjNNdBYTCfRSMHgB5qVydJgDdmOUDp9dADh3yPP8Bg+6z+1qRio4+tFRKvRhwM1 Yh/7VdmGJRFur8DwJv4YD+mytmPT8hs= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667901816; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=S4xjc/nQwJ6GnzpcV0nK0PWouPoszJ/ytdll+u4cDTE=; b=x/7nzlKDqln2H08tKylQhzq8i8uFYw3kzupqD2t3q+SVrwUfKWtu1Wrh7d+IT+9+uViQi2 9f514wHHjPSHun6nYopXo8AUruTE6qLP38WJK5mRMViQAJrtUrLncg3pCHUCgRD8IDiNp2 Iz22VL0qJ7HK28l/h/7+xPWJMXt9hRs= X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 5800F80008 Authentication-Results: imf30.hostedemail.com; dkim=none; spf=none (imf30.hostedemail.com: domain of hch@lst.de has no SPF policy when checking 213.95.11.211) smtp.mailfrom=hch@lst.de; dmarc=none X-Stat-Signature: copbt16ou8u5sqhwpimtkco8yyfdhu3c X-Rspam-User: X-HE-Tag: 1667901816-843830 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Nov 08, 2022 at 09:52:15AM +0000, Catalin Marinas wrote: > Since it's hard to guess the optimal swiotlb buffer for such platforms, > I think a follow-up step would be to use the DMA coherent pool for > bouncing if no swiotlb buffer is available. At least the pool can grow > dynamically. Yet another option would be to increase the swiotlb buffer > at run-time but it has an overhead for is_swiotlb_buffer(). Alex said he wanted to look into growing the swiotlb buffer on demand for other reason, so adding him to Cc to check if there has been any progress on that.