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[91.219.240.2]) by smtp.gmail.com with ESMTPSA id x13sm4631033wmj.5.2020.03.18.08.00.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Mar 2020 08:00:17 -0700 (PDT) From: Vitaly Kuznetsov To: Baoquan He Subject: Re: [PATCH v2 0/8] mm/memory_hotplug: allow to specify a default online_type In-Reply-To: <20200318144119.GD30899@MiWiFi-R3L-srv> References: <20200317104942.11178-1-david@redhat.com> <20200318130517.GC30899@MiWiFi-R3L-srv> <87d0993gto.fsf@vitty.brq.redhat.com> <20200318144119.GD30899@MiWiFi-R3L-srv> Date: Wed, 18 Mar 2020 16:00:15 +0100 Message-ID: <874kul3dz4.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain Content-Transfer-Encoding: quoted-printable X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Yumei Huang , linux-hyperv@vger.kernel.org, Michal Hocko , David Hildenbrand , Michal Hocko , linux-mm@kvack.org, Paul Mackerras , "K. Y. Srinivasan" , Wei Liu , Stephen Hemminger , "Rafael J. Wysocki" , Eduardo Habkost , Haiyang Zhang , Wei Yang , Oscar Salvador , Milan Zamazal , linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Igor Mammedov , Andrew Morton , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Baoquan He writes: > Is there a reason hyperV need boot with small memory, then enlarge it > with huge memory? Since it's a real case in hyperV, I guess there must > be reason, I am just curious. > It doesn't really *need* to but this can be utilized in e.g. 'hot standby' schemes I believe. Also, it may be enough if the administrator is just trying to e.g. double the size of RAM but the VM is already under memory pressure. I wouldn't say that these cases are common but afair bugs like 'I tried adding more memory to my VM and it just OOMed' were reported in the past. --=20 Vitaly