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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 28666C7EE29 for ; Fri, 9 Jun 2023 21:26:59 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1q7jcb-0006zT-2b; Fri, 09 Jun 2023 17:26:13 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1q7jcZ-0006zB-GN for qemu-devel@nongnu.org; Fri, 09 Jun 2023 17:26:11 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1q7jcX-0008VK-5U for qemu-devel@nongnu.org; Fri, 09 Jun 2023 17:26:11 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1686345968; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=5XA0v/Gcxpv6/a9edqzJDfMkpgPv2+sNI4m1jY1HPEU=; b=Wedn2HiP47Qz4fov2t7iiUY3m4+KPsbGIi+JQFacBBjZxK++ozLVdnJZWwChQrp9QxKfLS 3NpbD2MwsGvZaMeQA5TuI11Z41hZhxxLm6omuJJUw/WrhPTl6Kc3cZUUgreOWxk2XBZZ1/ BTYzAeIouBU+pTA6W/R7Q3HPvZzP3b0= Received: from mail-qk1-f200.google.com (mail-qk1-f200.google.com [209.85.222.200]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-112-moi2gjSPPPSQuDc-smQ4AA-1; Fri, 09 Jun 2023 17:26:06 -0400 X-MC-Unique: moi2gjSPPPSQuDc-smQ4AA-1 Received: by mail-qk1-f200.google.com with SMTP id af79cd13be357-75b337f2504so49490585a.0 for ; Fri, 09 Jun 2023 14:26:06 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1686345966; x=1688937966; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=5XA0v/Gcxpv6/a9edqzJDfMkpgPv2+sNI4m1jY1HPEU=; b=PyADoat8uBnEUN1MK3vADP/vkTpBCqpBctsIeMPAe9f3jnZCLz5D/a8uQ30YTrh9nD 5sYabFnd2tdpGf8jfwKHUcbx6ZRngJqj2LIGpdQgOSfdckIN8YeLGJleldNis6pIDiCC /8QQb2zAAQ96WrlnNJVcm+BF1MTu4HQ1cw1UxsoByv5wNJKwV+X3EM9cj/J43USU1kfM erstW9lcmeDKG9MnMvISyOrFVspMGIAzya408dPQ/JY7qCOA1FtJgL9PycixI5cb2SDu Y59QNMTefvMhieyrLyQ2dZEFauA/wkNVMeIR4Tl2JDFKwdoljXj4TuwZsq74gccYaj0g TGow== X-Gm-Message-State: AC+VfDz21P+d8Say8VQXXNvgVxpQrrqowB34OCXmDbus5ZGQlrHGbwQ7 V4v+xuqlp8aRWFLOPeLuLI/oLyXIFXVmw1+/J/F4i9mzNWFqxtySZ1C7wirTLBBtq0GS2zzxk94 +7t7N5Eejnow0JCw= X-Received: by 2002:a05:620a:3705:b0:75c:a2bb:5e10 with SMTP id de5-20020a05620a370500b0075ca2bb5e10mr2767677qkb.0.1686345966238; Fri, 09 Jun 2023 14:26:06 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ4sFhYs+lwc0QlBrpkxUHfCeM3HGIg7AvWexs1kzTwNFhwKJ06nhOeLb2u72cqN/m1DkmCGfw== X-Received: by 2002:a05:620a:3705:b0:75c:a2bb:5e10 with SMTP id de5-20020a05620a370500b0075ca2bb5e10mr2767656qkb.0.1686345965949; Fri, 09 Jun 2023 14:26:05 -0700 (PDT) Received: from x1n (cpe5c7695f3aee0-cm5c7695f3aede.cpe.net.cable.rogers.com. [99.254.144.39]) by smtp.gmail.com with ESMTPSA id c23-20020a05620a135700b0074e0abe59a0sm1279114qkl.78.2023.06.09.14.26.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Jun 2023 14:26:04 -0700 (PDT) Date: Fri, 9 Jun 2023 17:26:03 -0400 From: Peter Xu To: "Duan, Zhenzhong" Cc: Jason Gunthorpe , "Liu, Yi L" , "qemu-devel@nongnu.org" , "mst@redhat.com" , "jasowang@redhat.com" , "pbonzini@redhat.com" , "richard.henderson@linaro.org" , "eduardo@habkost.net" , "marcel.apfelbaum@gmail.com" , "alex.williamson@redhat.com" , "clg@redhat.com" , "david@redhat.com" , "philmd@linaro.org" , "kwankhede@nvidia.com" , "cjia@nvidia.com" , "Peng, Chao P" Subject: Re: [PATCH v3 5/5] intel_iommu: Optimize out some unnecessary UNMAP calls Message-ID: References: <20230608095231.225450-1-zhenzhong.duan@intel.com> <20230608095231.225450-6-zhenzhong.duan@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Received-SPF: pass client-ip=170.10.133.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, Jun 09, 2023 at 05:49:06AM +0000, Duan, Zhenzhong wrote: > Seems vtd_page_walk_one() already works in above way, checking mapping > changes and calling kernel for changed entries? Agreed in most cases, but the path this patch modified is not? E.g. it happens in rare cases where we simply want to unmap everything (e.g. on a system reset, or invalid context entry)? That's also why I'm curious whether perf of this path matters at all (and assuming now we all agree that's the only goal now..), because afaiu it didn't really trigger in common paths. -- Peter Xu