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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 4F52DC433ED for ; Wed, 7 Apr 2021 15:10:46 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D0CB961382 for ; Wed, 7 Apr 2021 15:10:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D0CB961382 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 004446B007D; Wed, 7 Apr 2021 11:10:45 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EF4926B007E; Wed, 7 Apr 2021 11:10:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DE34A6B0080; Wed, 7 Apr 2021 11:10:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0018.hostedemail.com [216.40.44.18]) by kanga.kvack.org (Postfix) with ESMTP id C44336B007D for ; Wed, 7 Apr 2021 11:10:44 -0400 (EDT) Received: from smtpin34.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 6B02212CD for ; Wed, 7 Apr 2021 15:10:44 +0000 (UTC) X-FDA: 78005908008.34.27DE749 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by imf07.hostedemail.com (Postfix) with ESMTP id 775EAA00038D for ; Wed, 7 Apr 2021 15:10:42 +0000 (UTC) IronPort-SDR: 2DWC3lEX5ROzyjgi8JaKnxHAcWrpnNS+SwVV6hxFS2MYD41JWPLwLMsz2J5GnatwOp1GpJmEA0 O1sTCUD9f5Uw== X-IronPort-AV: E=McAfee;i="6000,8403,9947"; a="190124406" X-IronPort-AV: E=Sophos;i="5.82,203,1613462400"; d="scan'208";a="190124406" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Apr 2021 08:10:40 -0700 IronPort-SDR: Nh2sXErIvHnCufsdheEBQ6UWLhutJYLYv3s41okOLzye7V6PJUrqWrrsYr6rigFmkyppdLuIet kqmSSIH5M6BA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.82,203,1613462400"; d="scan'208";a="530238532" Received: from tassilo.jf.intel.com (HELO tassilo.localdomain) ([10.54.74.11]) by orsmga004.jf.intel.com with ESMTP; 07 Apr 2021 08:10:40 -0700 Received: by tassilo.localdomain (Postfix, from userid 1000) id 0F76030027C; Wed, 7 Apr 2021 08:10:40 -0700 (PDT) From: Andi Kleen To: David Hildenbrand Cc: "Kirill A. Shutemov" , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Sean Christopherson , Jim Mattson , David Rientjes , "Edgecombe\, Rick P" , "Kleen\, Andi" , "Yamahata\, Isaku" , x86@kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" , Oscar Salvador , Naoya Horiguchi Subject: Re: [RFCv1 7/7] KVM: unmap guest memory using poisoned pages References: <20210402152645.26680-1-kirill.shutemov@linux.intel.com> <20210402152645.26680-8-kirill.shutemov@linux.intel.com> <5e934d94-414c-90de-c58e-34456e4ab1cf@redhat.com> Date: Wed, 07 Apr 2021 08:10:40 -0700 In-Reply-To: <5e934d94-414c-90de-c58e-34456e4ab1cf@redhat.com> (David Hildenbrand's message of "Wed, 7 Apr 2021 16:55:54 +0200") Message-ID: <87v98yuo3z.fsf@linux.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 775EAA00038D X-Stat-Signature: 9mq7xpy7oiuo8imo3588h4kpxwopxd4a Received-SPF: none (linux.intel.com>: No applicable sender policy available) receiver=imf07; identity=mailfrom; envelope-from=""; helo=mga11.intel.com; client-ip=192.55.52.93 X-HE-DKIM-Result: none/none X-HE-Tag: 1617808242-746035 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: David Hildenbrand writes: > I have no idea how expensive would be bouncing writes (and reads?) > through the kernel. Did you ever experiment with that/evaluate that? I would expect it to be quite expensive, as in virtio IO performance tanking. -Andi