From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Subject: Re: [PATCH RFC] virtio_balloon: conservative balloon page shrinking Date: Thu, 6 Feb 2020 10:49:22 +0100 Message-ID: <1f350e9f-e19d-8ef7-b63c-86bb4f52acc5@redhat.com> References: <1580976107-16013-1-git-send-email-wei.w.wang@intel.com> <6ccbfeea-de66-20d7-0e08-a5834a3c3d3f@redhat.com> <286AC319A985734F985F78AFA26841F73E4238BA@shsmsx102.ccr.corp.intel.com> <80f975c9-5f18-a613-6412-292dafd34dfe@redhat.com> <286AC319A985734F985F78AFA26841F73E42397C@shsmsx102.ccr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <286AC319A985734F985F78AFA26841F73E42397C@shsmsx102.ccr.corp.intel.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: "Wang, Wei W" , "linux-kernel@vger.kernel.org" , "virtualization@lists.linux-foundation.org" Cc: "tysand@google.com" , "mst@redhat.com" , "alexander.h.duyck@linux.intel.com" , "rientjes@google.com" , "mhocko@kernel.org" , "namit@vmware.com" , "penguin-kernel@I-love.SAKURA.ne.jp" List-Id: virtualization@lists.linuxfoundation.org On 06.02.20 10:44, Wang, Wei W wrote: > On Thursday, February 6, 2020 5:32 PM, David Hildenbrand wrote: >> >> If the page cache is empty, a drop_slab() will deflate the whole balloon if I >> am not wrong. >> >> Especially, a echo 3 > /proc/sys/vm/drop_caches >> >> will first drop the page cache and then drop_slab() > > Then that's the problem of "echo 3 > /proc/sys/vm/drop_cache" itself. It invokes other shrinkers as well (if considered an issue), need to be tweaked in the mm. In short, I don't like this approach as long as a drop_slab() can deflate the whole balloon and don't think this is the right approach then. -- Thanks, David / dhildenb