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 0E4DEC433F5 for ; Fri, 27 May 2022 12:38:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348488AbiE0MiZ (ORCPT ); Fri, 27 May 2022 08:38:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54164 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244530AbiE0MiD (ORCPT ); Fri, 27 May 2022 08:38:03 -0400 Received: from mail-pl1-x62d.google.com (mail-pl1-x62d.google.com [IPv6:2607:f8b0:4864:20::62d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E5D3F1A8E21; Fri, 27 May 2022 05:20:59 -0700 (PDT) Received: by mail-pl1-x62d.google.com with SMTP id s14so3995785plk.8; Fri, 27 May 2022 05:20:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:date:mime-version:user-agent:reply-to:subject :content-language:to:cc:references:from:organization:in-reply-to :content-transfer-encoding; bh=iJRtC6FZ8/ulUwIgZS39WaHh+o9Ilrp1wW7JFepItc0=; b=qSLrw/xH/l+UVkirRAZz/8FZ0ZZjL5uSuxHX7LIvFmTyb2UbiCPcMLJ7FPei3UtAUG /ngnpOH2XTctk2kEZnq1GlxnsaUo07pYEaINTbsCgqrOHFJQt24gZQ+ILHVpJtEzyjME 4UrYxkBjVTiElekXp+gzuW+XAGU6/RtkFdOXe+8dCI4p/cXb8vCquU8DfILasd9urWSo KHl1WoMhA+RFZrgD0SzbVWJBhfTAXtdoOWgI9FuBo/sPpuLmHrpwM/ULSW9MXKoel/hj SOkK23tv+gEHbYe80ZKZG6/zw7Y4B7GfXZTNIaeke82Up93gcA/IDSi6cSpXHo/eaf+S 8+fw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:reply-to :subject:content-language:to:cc:references:from:organization :in-reply-to:content-transfer-encoding; bh=iJRtC6FZ8/ulUwIgZS39WaHh+o9Ilrp1wW7JFepItc0=; b=IadmFGgIBN5MiOuyC90KPCx7/qMyYhSEPcE7+u2jVfyPyYS3b32xJ/DtgLYnpqyBhL YOJwsGcQ+bi/pT3hptDW7HCRdS52SeM1J0OKI4NCDz7JZhfrCXauGqmE0c7Qy3ksG3g5 GcdGTfPUq4gsfxpVpDo+9tMyZVzvZ6bH6EhZgplvV/B/mH1l+Cg1Q5pGA+ClevVacl4b r1Ap/vD7Csw9kKsst8U40kOlYOZb59ciTEQr+ra5KeR6o7z1CQvPhBrCChKwQE51FvvW fHeKk3tj+vI/+rqzKs68c4fE0w/zSO3+SlYJanBCYbmXgRNcgE316MUpfqJutsVvNmlJ rruA== X-Gm-Message-State: AOAM532neNjBGPbbwBT1Tn4oVcnf/E6ynMWF14+VNqBovPIrVPA1xMJA 5rFc8Jz7F82eoREgWNfbnpU= X-Google-Smtp-Source: ABdhPJyhM4+yaDnivdy5jmDUaKkUnBpSnlKSW9KCRZAyRvH55Ju8bIw6KCyC4TQtzI1iKBxbIA25WA== X-Received: by 2002:a17:903:2305:b0:163:64c7:f9ff with SMTP id d5-20020a170903230500b0016364c7f9ffmr11636415plh.46.1653654059447; Fri, 27 May 2022 05:20:59 -0700 (PDT) Received: from ?IPV6:2404:f801:0:5:8000::597? ([2404:f801:9000:18:efec::597]) by smtp.gmail.com with ESMTPSA id c11-20020a170902d48b00b0015ea8b4b8f3sm3463974plg.263.2022.05.27.05.20.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 27 May 2022 05:20:58 -0700 (PDT) Message-ID: <56243d2b-d7f6-9e45-d5fd-3af7767d52e3@gmail.com> Date: Fri, 27 May 2022 20:20:50 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 Reply-To: tiala@microsoft.com Subject: Re: [RFC PATCH V3 2/2] net: netvsc: Allocate per-device swiotlb bounce buffer for netvsc Content-Language: en-US To: Dexuan Cui , KY Srinivasan , Haiyang Zhang , Stephen Hemminger , "wei.liu@kernel.org" , "davem@davemloft.net" , "kuba@kernel.org" , "pabeni@redhat.com" , "hch@infradead.org" , "m.szyprowski@samsung.com" , "robin.murphy@arm.com" , "Michael Kelley (LINUX)" Cc: Tianyu Lan , "iommu@lists.linux-foundation.org" , "linux-hyperv@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "netdev@vger.kernel.org" , vkuznets , "konrad.wilk@oracle.com" , "hch@lst.de" , "parri.andrea@gmail.com" , "thomas.lendacky@amd.com" , "andi.kleen@intel.com" , "kirill.shutemov" References: <20220526120113.971512-1-ltykernel@gmail.com> <20220526120113.971512-3-ltykernel@gmail.com> From: Tianyu Lan Organization: Microsft In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 5/27/2022 2:43 AM, Dexuan Cui wrote: >> From: Tianyu Lan >> Sent: Thursday, May 26, 2022 5:01 AM >> ... >> @@ -119,6 +124,10 @@ static void netvsc_subchan_work(struct work_struct >> *w) >> nvdev->max_chn = 1; >> nvdev->num_chn = 1; >> } >> + >> + /* Allocate boucne buffer.*/ >> + swiotlb_device_allocate(&hdev->device, nvdev->num_chn, >> + 10 * IO_TLB_BLOCK_UNIT); >> } > > Looks like swiotlb_device_allocate() is not called if the netvsc device > has only 1 primary channel and no sub-schannel, e.g. in the case of > single-vCPU VM? When there is only sinlgeļ¼Œthere seems not to be much performance penalty. But you are right, we should keep the same behavior when single CPU and multi CPU. Will update in the next version. Thanks.