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,NICE_REPLY_A,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 9B108C4338F for ; Mon, 2 Aug 2021 17:19:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6BCA061102 for ; Mon, 2 Aug 2021 17:19:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230025AbhHBRT3 (ORCPT ); Mon, 2 Aug 2021 13:19:29 -0400 Received: from frasgout.his.huawei.com ([185.176.79.56]:3565 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229593AbhHBRT1 (ORCPT ); Mon, 2 Aug 2021 13:19:27 -0400 Received: from fraeml711-chm.china.huawei.com (unknown [172.18.147.200]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4Gdl955vfwz6F7yt; Tue, 3 Aug 2021 01:19:05 +0800 (CST) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by fraeml711-chm.china.huawei.com (10.206.15.60) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Mon, 2 Aug 2021 19:19:14 +0200 Received: from [10.47.87.154] (10.47.87.154) 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 15.1.2176.2; Mon, 2 Aug 2021 18:19:13 +0100 Subject: Re: [PATCH v4 5/6] iova: Add iova_len argument to init_iova_domain() From: John Garry To: Robin Murphy , Will Deacon CC: , , , , , , , , , , , , , , References: <1626259003-201303-1-git-send-email-john.garry@huawei.com> <1626259003-201303-6-git-send-email-john.garry@huawei.com> <20210802150644.GD28735@willie-the-truck> <1d06eda1-9961-d023-f5e7-fe87e768f067@arm.com> Message-ID: <099da8be-00dc-09cb-d72c-8e7b4b724f7c@huawei.com> Date: Mon, 2 Aug 2021 18:18:45 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.47.87.154] X-ClientProxiedBy: lhreml713-chm.china.huawei.com (10.201.108.64) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/08/2021 17:40, John Garry wrote: > On 02/08/2021 17:16, Robin Murphy wrote: >> On 2021-08-02 17:06, John Garry wrote: >>> On 02/08/2021 16:06, Will Deacon wrote: >>>> On Wed, Jul 14, 2021 at 06:36:42PM +0800, John Garry wrote: >>>>> Add max opt argument to init_iova_domain(), and use it to set the >>>>> rcaches >>>>> range. >>>>> >>>>> Also fix up all users to set this value (at 0, meaning use default). >>>> Wrap that in init_iova_domain_defaults() to avoid the mysterious 0? >>> >>> Sure, I can do something like that. I actually did have separate >>> along those lines in v3 before I decided to change it. >> >> Y'know, at this point I'm now starting to seriously wonder whether >> moving the rcaches into iommu_dma_cookie wouldn't make a whole lot of >> things simpler... :/ > > As I see, the rcache stuff isn't really specific to IOVA anyway, so it > seems sane. > >> >> Does that sound like crazy talk to you, or an idea worth entertaining? > > If you're going to start moving things, has anyone considered putting > rcache support in lib as a generic solution to "Magazines and Vmem: .." > paper? Having said that, I still think that the rcache code has certain scalability issues, as discussed before. So making more generic and then discarding would be less than ideal. Thanks, john