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=-6.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 F29D1C07E9A for ; Wed, 14 Jul 2021 14:24:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BEB6D6117A for ; Wed, 14 Jul 2021 14:24:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232268AbhGNO12 (ORCPT ); Wed, 14 Jul 2021 10:27:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:52870 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231977AbhGNO11 (ORCPT ); Wed, 14 Jul 2021 10:27:27 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 57CFD61154; Wed, 14 Jul 2021 14:24:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1626272675; bh=uGr4g/Ee6pV+EYvldgWLzrmg2C688Tc8vlJSlq63pk8=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=cET9p+pZsUlfkwOTPAtB5/mDe7yDJsg4FzfZffrQRnOVuD0rYqFVb6ZeVscmNktjM bNA7IV3qJNt14ok7rAS5FJ3LfAXGNCKyl42bXGsyuyHfNyQIkBZURhjTYhGVDqTBSH TxgYKIosOSty1JV9snDp7ZdJ2NYRoq/gkKi0nMNIZMI7NA/frs3I90G5cVnZT1Cid6 WIvbWsHG0zjCrPhEFXqGGcASjc9YI16y+p/Xh8ELeyNyhOoZo7e9/786yUHZUa6oAg Do/lYC41xrtfNZS757OeycCgPNWOg2pYEI3fjwaTGVfKxUaSRe6HSlXOboC0wLIOdF XC0EsUYXlRjdg== Subject: Re: [PATCH v7 00/15] Optimizing iommu_[map/unmap] performance To: Georgi Djakov , will@kernel.org, robin.murphy@arm.com Cc: joro@8bytes.org, isaacm@codeaurora.org, baolu.lu@linux.intel.com, pratikp@codeaurora.org, iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <1623850736-389584-1-git-send-email-quic_c_gdjako@quicinc.com> From: Georgi Djakov Message-ID: Date: Wed, 14 Jul 2021 17:24:29 +0300 MIME-Version: 1.0 In-Reply-To: <1623850736-389584-1-git-send-email-quic_c_gdjako@quicinc.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16.06.21 16:38, Georgi Djakov wrote: > When unmapping a buffer from an IOMMU domain, the IOMMU framework unmaps > the buffer at a granule of the largest page size that is supported by > the IOMMU hardware and fits within the buffer. For every block that > is unmapped, the IOMMU framework will call into the IOMMU driver, and > then the io-pgtable framework to walk the page tables to find the entry > that corresponds to the IOVA, and then unmaps the entry. > > This can be suboptimal in scenarios where a buffer or a piece of a > buffer can be split into several contiguous page blocks of the same size. > For example, consider an IOMMU that supports 4 KB page blocks, 2 MB page > blocks, and 1 GB page blocks, and a buffer that is 4 MB in size is being > unmapped at IOVA 0. The current call-flow will result in 4 indirect calls, > and 2 page table walks, to unmap 2 entries that are next to each other in > the page-tables, when both entries could have been unmapped in one shot > by clearing both page table entries in the same call. > > The same optimization is applicable to mapping buffers as well, so > these patches implement a set of callbacks called unmap_pages and > map_pages to the io-pgtable code and IOMMU drivers which unmaps or maps > an IOVA range that consists of a number of pages of the same > page size that is supported by the IOMMU hardware, and allows for > manipulating multiple page table entries in the same set of indirect > calls. The reason for introducing these callbacks is to give other IOMMU > drivers/io-pgtable formats time to change to using the new callbacks, so > that the transition to using this approach can be done piecemeal. Hi Will, Did you get a chance to look at this patchset? Most patches are already acked/reviewed and all still applies clean on rc1. Thanks, Georgi