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 A71D2C433F5 for ; Mon, 30 May 2022 07:41:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233686AbiE3Hlf (ORCPT ); Mon, 30 May 2022 03:41:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48474 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232453AbiE3Hla (ORCPT ); Mon, 30 May 2022 03:41:30 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 33CDB12ABF for ; Mon, 30 May 2022 00:41:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1653896488; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Ioljxq6PuUu4lxQDlH2MK2dNxIoWh+YwDSpERyNHcYc=; b=XvvzWp4Bbvuec6SPEujVI3QqJPEREweV2vgK9bMN7ZdrA/6fg0c0ScUCSZ/UJ66eM1qfe0 oEuRc3xxI5fz59GitkUNXgL1VptzUcrZJF6ra3reUqGGTSvQLeTS4gmLV1TkOLNL2o9xjv WeZZLpCR/JOyxrjO9KkWV/i7bIPo5fc= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-637-lLl-GGQbPY2Mcr6iJ0B-TA-1; Mon, 30 May 2022 03:41:25 -0400 X-MC-Unique: lLl-GGQbPY2Mcr6iJ0B-TA-1 Received: by mail-wm1-f69.google.com with SMTP id j40-20020a05600c1c2800b003972dbb1066so9286045wms.4 for ; Mon, 30 May 2022 00:41:24 -0700 (PDT) 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 :content-language:to:cc:references:from:organization:subject :in-reply-to:content-transfer-encoding; bh=Ioljxq6PuUu4lxQDlH2MK2dNxIoWh+YwDSpERyNHcYc=; b=vONZ4LKHwLYZIVy8TnHcCu47rvkVLXtui2mZ+HCqxmZRys23WLWLIXg8HPlar1OsRz l1B1EpyvMFuqrgSjrcNEA/S84FLVkq6hcJitCtqmuZ7QN48av9bryeGQ3qjeb08q39CU Izxwpaxhp/fYt2sRw2d9PjajChe1RgoKih0SzvBrbWKCA4HAlURZ5b+PDb43M9N9Tyaq QBXRb3J1ne8P55Ev5XnNNGxi9RYB404E5C5vgLL9r27tenW8iqX5ldtuj3nVdYduh764 l+KTOvehq3WkySYlKz8c6pqOg6DyDl1kdqkFSgr7lE3SL47K+PxBts719tWCrtIbwXqA JD/A== X-Gm-Message-State: AOAM5312sxGIKrAGvA/Ye/wzytWhNy4CMrZQLaUo6lC1hd3S9zAU1eOy KDqXsrKl9SYGfjJk/LzCJZ5E2a+TYMAZuRhn+PK5ciXKMDLR9U90gc0HiT/OX78qYVKBjl0jAVW Z2aURjkW5SAua/l5hcikZt5hP X-Received: by 2002:a05:6000:144f:b0:20f:d6e8:a54 with SMTP id v15-20020a056000144f00b0020fd6e80a54mr30927446wrx.482.1653896483860; Mon, 30 May 2022 00:41:23 -0700 (PDT) X-Google-Smtp-Source: ABdhPJygmIHMNmIMibGNEd206s8mAH/2ItntHqoVW3Fp9CPDeipNv0CP+C+hoSkZ/LeN5Ih++u+6aA== X-Received: by 2002:a05:6000:144f:b0:20f:d6e8:a54 with SMTP id v15-20020a056000144f00b0020fd6e80a54mr30927434wrx.482.1653896483573; Mon, 30 May 2022 00:41:23 -0700 (PDT) Received: from ?IPV6:2003:cb:c704:7c00:aaa9:2ce5:5aa0:f736? (p200300cbc7047c00aaa92ce55aa0f736.dip0.t-ipconnect.de. [2003:cb:c704:7c00:aaa9:2ce5:5aa0:f736]) by smtp.gmail.com with ESMTPSA id h9-20020a7bc929000000b003974a3af623sm9688836wml.17.2022.05.30.00.41.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 30 May 2022 00:41:23 -0700 (PDT) Message-ID: <0d266c61-605d-ce0c-4274-b0c7e10f845a@redhat.com> Date: Mon, 30 May 2022 09:41:22 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 Content-Language: en-US To: zhenwei pi , Peter Xu , Jue Wang Cc: Andrew Morton , jasowang@redhat.com, LKML , Linux MM , mst@redhat.com, =?UTF-8?B?SE9SSUdVQ0hJIE5BT1lBKOWggOWPoyDnm7TkuZ8p?= , Paolo Bonzini , qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org References: <24a95dea-9ea6-a904-7c0b-197961afa1d1@bytedance.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH 0/3] recover hardware corrupted page by virtio balloon In-Reply-To: <24a95dea-9ea6-a904-7c0b-197961afa1d1@bytedance.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27.05.22 08:32, zhenwei pi wrote: > On 5/27/22 02:37, Peter Xu wrote: >> On Wed, May 25, 2022 at 01:16:34PM -0700, Jue Wang wrote: >>> The hypervisor _must_ emulate poisons identified in guest physical >>> address space (could be transported from the source VM), this is to >>> prevent silent data corruption in the guest. With a paravirtual >>> approach like this patch series, the hypervisor can clear some of the >>> poisoned HVAs knowing for certain that the guest OS has isolated the >>> poisoned page. I wonder how much value it provides to the guest if the >>> guest and workload are _not_ in a pressing need for the extra KB/MB >>> worth of memory. >> >> I'm curious the same on how unpoisoning could help here. The reasoning >> behind would be great material to be mentioned in the next cover letter. >> >> Shouldn't we consider migrating serious workloads off the host already >> where there's a sign of more severe hardware issues, instead? >> >> Thanks, >> > > I'm maintaining 1000,000+ virtual machines, from my experience: > UE is quite unusual and occurs randomly, and I did not hit UE storm case > in the past years. The memory also has no obvious performance drop after > hitting UE. > > I hit several CE storm case, the performance memory drops a lot. But I > can't find obvious relationship between UE and CE. > > So from the point of my view, to fix the corrupted page for VM seems > good enough. And yes, unpoisoning several pages does not help > significantly, but it is still a chance to make the virtualization better. > I'm curious why we should care about resurrecting a handful of poisoned pages in a VM. The cover letter doesn't touch on that. IOW, I'm missing the motivation why we should add additional code+complexity to unpoison pages at all. If we're talking about individual 4k pages, it's certainly sub-optimal, but does it matter in practice? I could understand if we're losing megabytes of memory. But then, I assume the workload might be seriously harmed either way already? I assume when talking about "the performance memory drops a lot", you imply that this patch set can mitigate that performance drop? But why do you see a performance drop? Because we might lose some possible THP candidates (in the host or the guest) and you want to plug does holes? I assume you'll see a performance drop simply because poisoning memory is expensive, including migrating pages around on CE. If you have some numbers to share, especially before/after this change, that would be great. -- Thanks, David / dhildenb 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 smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (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 F3F90C433EF for ; Mon, 30 May 2022 07:41:33 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id 8B5C641940; Mon, 30 May 2022 07:41:33 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id C_z25EEwzvU3; Mon, 30 May 2022 07:41:32 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp4.osuosl.org (Postfix) with ESMTPS id A4A4D418D1; Mon, 30 May 2022 07:41:31 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 7DD68C0032; Mon, 30 May 2022 07:41:31 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 2F722C002D for ; Mon, 30 May 2022 07:41:30 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id F368B408F1 for ; Mon, 30 May 2022 07:41:29 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Authentication-Results: smtp2.osuosl.org (amavisd-new); dkim=pass (1024-bit key) header.d=redhat.com Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Y5H2F1aF0e6h for ; Mon, 30 May 2022 07:41:28 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by smtp2.osuosl.org (Postfix) with ESMTPS id A999F400A8 for ; Mon, 30 May 2022 07:41:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1653896487; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Ioljxq6PuUu4lxQDlH2MK2dNxIoWh+YwDSpERyNHcYc=; b=LRGXoVwAREXrPCfx90D0BjgX77Xc/RNMGPEAME4LCi0Pduhf9UFW8fiy2ITPVsx+R+ltpM bPkKa5av2hxSRrl5mrjgK6FHv3skKsyayI8ygpSCO1Xe/vfS6U0t0jb9hRBqTOJnPhKR0z 63E25nNqQqb1UEmQAmqCpGK7lbwtC7w= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-264-fN5Ms56iOf6popZmvLSfFQ-1; Mon, 30 May 2022 03:41:25 -0400 X-MC-Unique: fN5Ms56iOf6popZmvLSfFQ-1 Received: by mail-wm1-f70.google.com with SMTP id r6-20020a05600c35c600b0039740f3d32dso9230079wmq.9 for ; Mon, 30 May 2022 00:41:24 -0700 (PDT) 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 :content-language:to:cc:references:from:organization:subject :in-reply-to:content-transfer-encoding; bh=Ioljxq6PuUu4lxQDlH2MK2dNxIoWh+YwDSpERyNHcYc=; b=8Aqk+TSRuIC/unsg7QrzKik3Ak8twOHNxYuOyhzByHENr2aImnbxTU8KF9zjd4Udw3 tUHTgqGSqAIAI2lZDk2garR+FDqzKaLyW10j+DyRYCr30ojHMyo1ywJLaa9FAJwEucE7 785fySa4TuGQMrK3+kf1ESFnw7JdXottKMZXVwqIqFRB1ZoaAzLqig8fehyPX0lgL0zC 01qW1p3s0lpQQNGDN/9e4JX3bneZl3r73korxEJa69+toS3hV/ihN49HU5R1hfkFgiHe ohjkQ61pGc97GFKGSUsWORf6Y2wZqfwWxbxS115P8Xcr0odQEnoEdNupEje1+yPx4sSA BsnQ== X-Gm-Message-State: AOAM531ZJnJzkCwyEneATHA99SsSMlQAkFToj9qdcpK7JWhy4kKZx6yw MYd8feVZDllITe++JVhU1j14Rc5+0o6Q2TmF8UQepESX35XODlHDdE1sdY6080rn7dUsFMjupML 90lvcrAx7Ytv4D9xvwsmlNORHjYN2xcku9EzYZwzLog== X-Received: by 2002:a05:6000:144f:b0:20f:d6e8:a54 with SMTP id v15-20020a056000144f00b0020fd6e80a54mr30927451wrx.482.1653896483862; Mon, 30 May 2022 00:41:23 -0700 (PDT) X-Google-Smtp-Source: ABdhPJygmIHMNmIMibGNEd206s8mAH/2ItntHqoVW3Fp9CPDeipNv0CP+C+hoSkZ/LeN5Ih++u+6aA== X-Received: by 2002:a05:6000:144f:b0:20f:d6e8:a54 with SMTP id v15-20020a056000144f00b0020fd6e80a54mr30927434wrx.482.1653896483573; Mon, 30 May 2022 00:41:23 -0700 (PDT) Received: from ?IPV6:2003:cb:c704:7c00:aaa9:2ce5:5aa0:f736? 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[2003:cb:c704:7c00:aaa9:2ce5:5aa0:f736]) by smtp.gmail.com with ESMTPSA id h9-20020a7bc929000000b003974a3af623sm9688836wml.17.2022.05.30.00.41.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 30 May 2022 00:41:23 -0700 (PDT) Message-ID: <0d266c61-605d-ce0c-4274-b0c7e10f845a@redhat.com> Date: Mon, 30 May 2022 09:41:22 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 To: zhenwei pi , Peter Xu , Jue Wang References: <24a95dea-9ea6-a904-7c0b-197961afa1d1@bytedance.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH 0/3] recover hardware corrupted page by virtio balloon In-Reply-To: <24a95dea-9ea6-a904-7c0b-197961afa1d1@bytedance.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Cc: mst@redhat.com, =?UTF-8?B?SE9SSUdVQ0hJIE5BT1lBKOWggOWPoyDnm7TkuZ8p?= , LKML , qemu-devel@nongnu.org, Linux MM , Paolo Bonzini , Andrew Morton , virtualization@lists.linux-foundation.org X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" On 27.05.22 08:32, zhenwei pi wrote: > On 5/27/22 02:37, Peter Xu wrote: >> On Wed, May 25, 2022 at 01:16:34PM -0700, Jue Wang wrote: >>> The hypervisor _must_ emulate poisons identified in guest physical >>> address space (could be transported from the source VM), this is to >>> prevent silent data corruption in the guest. With a paravirtual >>> approach like this patch series, the hypervisor can clear some of the >>> poisoned HVAs knowing for certain that the guest OS has isolated the >>> poisoned page. I wonder how much value it provides to the guest if the >>> guest and workload are _not_ in a pressing need for the extra KB/MB >>> worth of memory. >> >> I'm curious the same on how unpoisoning could help here. The reasoning >> behind would be great material to be mentioned in the next cover letter. >> >> Shouldn't we consider migrating serious workloads off the host already >> where there's a sign of more severe hardware issues, instead? >> >> Thanks, >> > > I'm maintaining 1000,000+ virtual machines, from my experience: > UE is quite unusual and occurs randomly, and I did not hit UE storm case > in the past years. The memory also has no obvious performance drop after > hitting UE. > > I hit several CE storm case, the performance memory drops a lot. But I > can't find obvious relationship between UE and CE. > > So from the point of my view, to fix the corrupted page for VM seems > good enough. And yes, unpoisoning several pages does not help > significantly, but it is still a chance to make the virtualization better. > I'm curious why we should care about resurrecting a handful of poisoned pages in a VM. The cover letter doesn't touch on that. IOW, I'm missing the motivation why we should add additional code+complexity to unpoison pages at all. If we're talking about individual 4k pages, it's certainly sub-optimal, but does it matter in practice? I could understand if we're losing megabytes of memory. But then, I assume the workload might be seriously harmed either way already? I assume when talking about "the performance memory drops a lot", you imply that this patch set can mitigate that performance drop? But why do you see a performance drop? Because we might lose some possible THP candidates (in the host or the guest) and you want to plug does holes? I assume you'll see a performance drop simply because poisoning memory is expensive, including migrating pages around on CE. If you have some numbers to share, especially before/after this change, that would be great. -- Thanks, David / dhildenb _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization