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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 6FB04C43142 for ; Thu, 2 Aug 2018 11:00:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0DD15214DC for ; Thu, 2 Aug 2018 11:00:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0DD15214DC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=I-love.SAKURA.ne.jp Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732033AbeHBMvT (ORCPT ); Thu, 2 Aug 2018 08:51:19 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:56484 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727223AbeHBMvT (ORCPT ); Thu, 2 Aug 2018 08:51:19 -0400 Received: from fsav405.sakura.ne.jp (fsav405.sakura.ne.jp [133.242.250.104]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id w72B0eve075443; Thu, 2 Aug 2018 20:00:40 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav405.sakura.ne.jp (F-Secure/fsigk_smtp/530/fsav405.sakura.ne.jp); Thu, 02 Aug 2018 20:00:40 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/530/fsav405.sakura.ne.jp) Received: from [192.168.1.8] (softbank126074194044.bbtec.net [126.74.194.44]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id w72B0ZCo075430 (version=TLSv1.2 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 2 Aug 2018 20:00:40 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Subject: Re: [PATCH v2 2/2] virtio_balloon: replace oom notifier with shrinker To: Wei Wang , Michal Hocko Cc: virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-mm@kvack.org, mst@redhat.com, akpm@linux-foundation.org References: <1532683495-31974-1-git-send-email-wei.w.wang@intel.com> <1532683495-31974-3-git-send-email-wei.w.wang@intel.com> <20180730090041.GC24267@dhcp22.suse.cz> <5B619599.1000307@intel.com> <20180801113444.GK16767@dhcp22.suse.cz> <5B62DDCC.3030100@intel.com> From: Tetsuo Handa Message-ID: <87d7ae45-79cb-e294-7397-0e45e2af49cd@I-love.SAKURA.ne.jp> Date: Thu, 2 Aug 2018 20:00:32 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <5B62DDCC.3030100@intel.com> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018/08/02 19:32, Wei Wang wrote: > On 08/01/2018 07:34 PM, Michal Hocko wrote: >> Do you have any numbers for how does this work in practice? > > It works in this way: for example, we can set the parameter, balloon_pages_to_shrink, > to shrink 1GB memory once shrink scan is called. Now, we have a 8GB guest, and we balloon > out 7GB. When shrink scan is called, the balloon driver will get back 1GB memory and give > them back to mm, then the ballooned memory becomes 6GB. Since shrinker might be called concurrently (am I correct?), the balloon might deflate far more than needed if it releases such much memory. If shrinker is used, releasing 256 pages might be sufficient.