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 1B62DC433F5 for ; Tue, 1 Mar 2022 11:53:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234638AbiCALy1 (ORCPT ); Tue, 1 Mar 2022 06:54:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49888 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232139AbiCALy0 (ORCPT ); Tue, 1 Mar 2022 06:54:26 -0500 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B51908AE74; Tue, 1 Mar 2022 03:53:45 -0800 (PST) Received: by verein.lst.de (Postfix, from userid 2407) id BD48368AFE; Tue, 1 Mar 2022 12:53:40 +0100 (CET) Date: Tue, 1 Mar 2022 12:53:40 +0100 From: Christoph Hellwig To: Tianyu Lan Cc: kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, m.szyprowski@samsung.com, robin.murphy@arm.com, michael.h.kelley@microsoft.com, Tianyu Lan , iommu@lists.linux-foundation.org, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, vkuznets@redhat.com, brijesh.singh@amd.com, konrad.wilk@oracle.com, parri.andrea@gmail.com, thomas.lendacky@amd.com, "krish.sadhukhan@oracle.com" , "kirill.shutemov@linux.intel.com" Subject: Re: [PATCH V2 1/2] Swiotlb: Add swiotlb_alloc_from_low_pages switch Message-ID: <20220301115340.GA3077@lst.de> References: <20220214081919.GA18337@lst.de> <4f433f07-05be-f81f-43e8-55c3f1af23b3@gmail.com> <20220214135834.GA30150@lst.de> <8d052867-ccff-f00f-7c89-cc26a4bfa347@gmail.com> <23f4a64d-5977-1816-8faa-fe7691ace2ff@gmail.com> <20220222080543.GA5412@lst.de> <00112505-4999-ac41-877e-49c4cc45312e@gmail.com> <20220222160039.GA13380@lst.de> <40f91949-58fa-4be2-5b01-ea34dda58670@gmail.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) Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org On Fri, Feb 25, 2022 at 10:28:54PM +0800, Tianyu Lan wrote: > One more perspective is that one device may have multiple queues and > each queues should have independent swiotlb bounce buffer to avoid spin > lock overhead. The number of queues is only available in the device > driver. This means new API needs to be called in the device driver > according to queue number. Well, given how hell bent people are on bounce buffering we might need some scalability work there anyway.