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 4FC59C6FA8F for ; Wed, 30 Aug 2023 18:59:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234118AbjH3S7I (ORCPT ); Wed, 30 Aug 2023 14:59:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40190 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343647AbjH3QbW (ORCPT ); Wed, 30 Aug 2023 12:31:22 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B448D107 for ; Wed, 30 Aug 2023 09:30:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1693413031; 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=aFrAeIckcxwdM3BGhgwY2df5vNbcEm/5Om84XOIOQVA=; b=iK7Zgf5Mz4uWuBMecbkL36Ivz1lK1rOmSV01hCiqRJdyMBNuMgAoUMhwX1pIuozEVbAnD7 zREkdzexEukpCGzBzQDIwKh/i+8IY9H8CcnrLQyKdFzw6SJ3+noOLoY7cbU2zr8yj1JEBX /7M5EetXlQw2+2kMmiudWkQyUqApExo= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-642-qqolbJ30Mw6xBe-koD_wGw-1; Wed, 30 Aug 2023 12:30:29 -0400 X-MC-Unique: qqolbJ30Mw6xBe-koD_wGw-1 Received: by mail-wr1-f70.google.com with SMTP id ffacd0b85a97d-31c5c55fd70so474471f8f.1 for ; Wed, 30 Aug 2023 09:30:29 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1693413028; x=1694017828; h=content-transfer-encoding:in-reply-to:organization:from:references :cc:to:content-language:subject:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=aFrAeIckcxwdM3BGhgwY2df5vNbcEm/5Om84XOIOQVA=; b=LapNM8o7GbO55IEIZH9RBBdbiJ5mzW4gvuESBPhWqyHlKjp8PMyl0/FGQRE9W8gKqN KslUk/jDKVVD7RT4gXlPMO36pZNbcmifS4wK7jatd12cNwqD0vDo1v4Q3afUgx8lWXZc i0Mj86k0hhmJjlsJ+jkw4vgqU+lKQxbgHgSfQ+X2envZe09ck8JD8wftFtgTvI3vh9ed X4bhs+2sp7q0KVtpKmb0shIiswyl/od4UIw3LSQsAMzq04vZdyE0aSSQkEalLXif1wmN mkMKPxeXiYHEsMANMpMsqmpVVNmB7VBKh8m4Dr5RDdrAWW4+ELmJ140dnUJeCTf31C2R ap1Q== X-Gm-Message-State: AOJu0YwrOfoFSfMS6wluSJGXv4W3fcHftOGyhYejgvL7BD44rq3eq7F9 FAK2Os1igMaUUi9nzIp33YypOsigB+imq9JloMYYV3ievFmBqu+DoDtMCq/Tnzah4Ut4zIn37hz UR58gzd6yoeQDNz382fnzOXP0 X-Received: by 2002:a5d:4a8d:0:b0:30e:56b3:60fe with SMTP id o13-20020a5d4a8d000000b0030e56b360femr131950wrq.4.1693413028098; Wed, 30 Aug 2023 09:30:28 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHXOzXnjzkCatETTts+G6EKS/KJiIlbcSxMP9jMzfgkBY6L4zKkYcXK5LkfkYMzCGwc/dBzyQ== X-Received: by 2002:a5d:4a8d:0:b0:30e:56b3:60fe with SMTP id o13-20020a5d4a8d000000b0030e56b360femr131931wrq.4.1693413027716; Wed, 30 Aug 2023 09:30:27 -0700 (PDT) Received: from [10.59.19.200] (pd956a06e.dip0.t-ipconnect.de. [217.86.160.110]) by smtp.gmail.com with ESMTPSA id w12-20020a5d4b4c000000b0031416362e23sm17169032wrs.3.2023.08.30.09.30.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 30 Aug 2023 09:30:27 -0700 (PDT) Message-ID: Date: Wed, 30 Aug 2023 18:30:25 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH] virtio_balloon: Fix endless deflation and inflation on arm64 Content-Language: en-US To: Gavin Shan , virtualization@lists.linux-foundation.org Cc: linux-kernel@vger.kernel.org, jasowang@redhat.com, mst@redhat.com, xuanzhuo@linux.alibaba.com, shan.gavin@gmail.com References: <20230829015421.920511-1-gshan@redhat.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230829015421.920511-1-gshan@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 29.08.23 03:54, Gavin Shan wrote: > The deflation request to the target, which isn't unaligned to the > guest page size causes endless deflation and inflation actions. For > example, we receive the flooding QMP events for the changes on memory > balloon's size after a deflation request to the unaligned target is > sent for the ARM64 guest, where we have 64KB base page size. > > /home/gavin/sandbox/qemu.main/build/qemu-system-aarch64 \ > -accel kvm -machine virt,gic-version=host -cpu host \ > -smp maxcpus=8,cpus=8,sockets=2,clusters=2,cores=2,threads=1 \ > -m 1024M,slots=16,maxmem=64G \ > -object memory-backend-ram,id=mem0,size=512M \ > -object memory-backend-ram,id=mem1,size=512M \ > -numa node,nodeid=0,memdev=mem0,cpus=0-3 \ > -numa node,nodeid=1,memdev=mem1,cpus=4-7 \ > : \ > -device virtio-balloon-pci,id=balloon0,bus=pcie.10 > > { "execute" : "balloon", "arguments": { "value" : 1073672192 } } > {"return": {}} > {"timestamp": {"seconds": 1693272173, "microseconds": 88667}, \ > "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}} > {"timestamp": {"seconds": 1693272174, "microseconds": 89704}, \ > "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}} > {"timestamp": {"seconds": 1693272175, "microseconds": 90819}, \ > "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}} > {"timestamp": {"seconds": 1693272176, "microseconds": 91961}, \ > "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}} > {"timestamp": {"seconds": 1693272177, "microseconds": 93040}, \ > "event": "BALLOON_CHANGE", "data": {"actual": 1073676288}} > {"timestamp": {"seconds": 1693272178, "microseconds": 94117}, \ > "event": "BALLOON_CHANGE", "data": {"actual": 1073676288}} > {"timestamp": {"seconds": 1693272179, "microseconds": 95337}, \ > "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}} > {"timestamp": {"seconds": 1693272180, "microseconds": 96615}, \ > "event": "BALLOON_CHANGE", "data": {"actual": 1073676288}} > {"timestamp": {"seconds": 1693272181, "microseconds": 97626}, \ > "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}} > {"timestamp": {"seconds": 1693272182, "microseconds": 98693}, \ > "event": "BALLOON_CHANGE", "data": {"actual": 1073676288}} > {"timestamp": {"seconds": 1693272183, "microseconds": 99698}, \ > "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}} > {"timestamp": {"seconds": 1693272184, "microseconds": 100727}, \ > "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}} > {"timestamp": {"seconds": 1693272185, "microseconds": 90430}, \ > "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}} > {"timestamp": {"seconds": 1693272186, "microseconds": 102999}, \ > "event": "BALLOON_CHANGE", "data": {"actual": 1073676288}} > : > > > Fix it by having the target aligned to the guest page size, 64KB > in this specific case. With this applied, no flooding QMP event > is observed and the memory balloon's size can be stablizied to > 0x3ffe0000 soon after the deflation request is sent. > > { "execute" : "balloon", "arguments": { "value" : 1073672192 } } > {"return": {}} > {"timestamp": {"seconds": 1693273328, "microseconds": 793075}, \ > "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}} > { "execute" : "query-balloon" } > {"return": {"actual": 1073610752}} > > Signed-off-by: Gavin Shan > --- > drivers/virtio/virtio_balloon.c | 13 ++++++++++++- > 1 file changed, 12 insertions(+), 1 deletion(-) > > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > index 5b15936a5214..625caac35264 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/virtio/virtio_balloon.c > @@ -386,6 +386,17 @@ static void stats_handle_request(struct virtio_balloon *vb) > virtqueue_kick(vq); > } > > +static inline s64 align_pages_up(s64 diff) > +{ > + if (diff == 0) > + return diff; > + > + if (diff > 0) > + return ALIGN(diff, VIRTIO_BALLOON_PAGES_PER_PAGE); > + > + return -ALIGN(-diff, VIRTIO_BALLOON_PAGES_PER_PAGE); > +} > + > static inline s64 towards_target(struct virtio_balloon *vb) > { > s64 target; > @@ -396,7 +407,7 @@ static inline s64 towards_target(struct virtio_balloon *vb) > &num_pages); > > target = num_pages; > - return target - vb->num_pages; We know that vb->num_pages is always multiples of VIRTIO_BALLOON_PAGES_PER_PAGE. Why not simply align target down? target = ALIGN(num_pages, VIRTIO_BALLOON_PAGES_PER_PAGE); return target - vb->num_pages; -- Cheers, David / dhildenb