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=-5.7 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 19F69C43216 for ; Fri, 27 Aug 2021 08:59:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 044B960FDC for ; Fri, 27 Aug 2021 08:59:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244685AbhH0JAH (ORCPT ); Fri, 27 Aug 2021 05:00:07 -0400 Received: from frasgout.his.huawei.com ([185.176.79.56]:3694 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232757AbhH0JAG (ORCPT ); Fri, 27 Aug 2021 05:00:06 -0400 Received: from fraeml711-chm.china.huawei.com (unknown [172.18.147.200]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4GwtsC5YsXz67RyC; Fri, 27 Aug 2021 16:57:51 +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 15.1.2308.8; Fri, 27 Aug 2021 10:59:16 +0200 Received: from [10.47.92.37] (10.47.92.37) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.8; Fri, 27 Aug 2021 09:59:14 +0100 Subject: Re: [PATCH v11 01/12] iova: Export alloc_iova_fast() and free_iova_fast() To: Yongji Xie CC: Will Deacon , "Michael S. Tsirkin" , kvm , Jason Wang , virtualization , Christian Brauner , Jonathan Corbet , "Matthew Wilcox" , Christoph Hellwig , "Dan Carpenter" , Stefano Garzarella , Liu Xiaodong , , Al Viro , "Stefan Hajnoczi" , , Jens Axboe , He Zhe , Greg KH , Randy Dunlap , linux-kernel , , , , Joe Perches , Robin Murphy , =?UTF-8?Q?Mika_Penttil=c3=a4?= References: <20210818120642.165-1-xieyongji@bytedance.com> <20210818120642.165-2-xieyongji@bytedance.com> <20210824140758-mutt-send-email-mst@kernel.org> <20210825095540.GA24546@willie-the-truck> <5f4eadda-5500-9bac-4368-48cfca6d0a4d@huawei.com> From: John Garry Message-ID: Date: Fri, 27 Aug 2021 10:03:03 +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: [10.47.92.37] X-ClientProxiedBy: lhreml706-chm.china.huawei.com (10.201.108.55) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 25/08/2021 13:17, Yongji Xie wrote: >> JFYI, There was a preliminary discussion to move the iova rcache code >> (which the iova fast alloc and free functions are based on) out of the >> iova code and maybe into dma-iommu (being the only user). There was >> other motivation. >> > Would it be better to move the code into ./lib as a general library? For a start we/I think that the rcache could be removed from the IOVA code, but prob should stay in drivers/iommu. I had another IOVA issue to solve, which complicates things. No solid plans. Need to talk to Robin more. > >> https://lore.kernel.org/linux-iommu/83de3911-145d-77c8-17c1-981e4ff825d3@arm.com/ >> >> Having more users complicates that... >> > Do we have some plan for this work? From our test [1], > iova_alloc_fast() is much better than iova_alloc(). So I'd like to use > it as much as possible > > [1]https://lore.kernel.org/kvm/CACycT3steXFeg7NRbWpo2J59dpYcumzcvM2zcPJAVe40-EvvEg@mail.gmail.com/ Well if you're alloc'ing and free'ing IOVAs a lot then I can imagine it is. Thanks, John