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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 45EDDC433EF for ; Thu, 28 Apr 2022 14:56:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348626AbiD1O7v (ORCPT ); Thu, 28 Apr 2022 10:59:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48098 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347213AbiD1O7s (ORCPT ); Thu, 28 Apr 2022 10:59:48 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 218664833E; Thu, 28 Apr 2022 07:56:34 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id CC8C61474; Thu, 28 Apr 2022 07:56:33 -0700 (PDT) Received: from [10.57.80.98] (unknown [10.57.80.98]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B923C3F774; Thu, 28 Apr 2022 07:56:29 -0700 (PDT) Message-ID: Date: Thu, 28 Apr 2022 15:56:24 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: [RFC PATCH 1/2] swiotlb: Split up single swiotlb lock Content-Language: en-GB To: Christoph Hellwig Cc: Tianyu Lan , m.szyprowski@samsung.com, michael.h.kelley@microsoft.com, kys@microsoft.com, parri.andrea@gmail.com, thomas.lendacky@amd.com, wei.liu@kernel.org, Andi Kleen , Tianyu Lan , linux-hyperv@vger.kernel.org, konrad.wilk@oracle.com, linux-kernel@vger.kernel.org, kirill.shutemov@intel.com, iommu@lists.linux-foundation.org, andi.kleen@intel.com, brijesh.singh@amd.com, vkuznets@redhat.com, hch@lst.de References: <20220428141429.1637028-1-ltykernel@gmail.com> <20220428141429.1637028-2-ltykernel@gmail.com> From: Robin Murphy In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022-04-28 15:45, Christoph Hellwig wrote: > On Thu, Apr 28, 2022 at 03:44:36PM +0100, Robin Murphy wrote: >> Rather than introduce this extra level of allocator complexity, how about >> just dividing up the initial SWIOTLB allocation into multiple io_tlb_mem >> instances? > > Yeah. We're almost done removing all knowledge of swiotlb from drivers, > so the very last thing I want is an interface that allows a driver to > allocate a per-device buffer. FWIW I'd already started thinking about having a distinct io_tlb_mem for non-coherent devices where vaddr is made non-cacheable to avoid the hassle of keeping the arch_dma_sync_* calls lined up, so I'm certainly in favour of bringing in a bit more flexibility at this level :) Robin.