From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tetsuo Handa Subject: Re: [PATCH v2 2/2] virtio_balloon: replace oom notifier with shrinker Date: Thu, 2 Aug 2018 20:00:32 +0900 Message-ID: <87d7ae45-79cb-e294-7397-0e45e2af49cd__11941.8864058845$1533209922$gmane$org@I-love.SAKURA.ne.jp> 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> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5B62DDCC.3030100@intel.com> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Wei Wang , Michal Hocko Cc: virtio-dev@lists.oasis-open.org, mst@redhat.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-mm@kvack.org, akpm@linux-foundation.org List-Id: virtualization@lists.linuxfoundation.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.