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[37.188.180.89]) by smtp.gmail.com with ESMTPSA id n2sm1696410wro.25.2020.03.18.06.54.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Mar 2020 06:54:10 -0700 (PDT) Date: Wed, 18 Mar 2020 14:54:08 +0100 From: Michal Hocko To: Baoquan He Cc: David Hildenbrand , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-hyperv@vger.kernel.org, Vitaly Kuznetsov , Yumei Huang , Igor Mammedov , Eduardo Habkost , Milan Zamazal , Andrew Morton , Benjamin Herrenschmidt , Greg Kroah-Hartman , Haiyang Zhang , "K. Y. Srinivasan" , Michael Ellerman , Oscar Salvador , Paul Mackerras , "Rafael J. Wysocki" , Stephen Hemminger , Wei Liu , Wei Yang Subject: Re: [PATCH v2 0/8] mm/memory_hotplug: allow to specify a default online_type Message-ID: <20200318135408.GP21362@dhcp22.suse.cz> References: <20200317104942.11178-1-david@redhat.com> <20200318130517.GC30899@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200318130517.GC30899@MiWiFi-R3L-srv> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 18-03-20 21:05:17, Baoquan He wrote: > On 03/17/20 at 11:49am, David Hildenbrand wrote: > > Distributions nowadays use udev rules ([1] [2]) to specify if and > > how to online hotplugged memory. The rules seem to get more complex with > > many special cases. Due to the various special cases, > > CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE cannot be used. All memory hotplug > > is handled via udev rules. > > > > Everytime we hotplug memory, the udev rule will come to the same > > conclusion. Especially Hyper-V (but also soon virtio-mem) add a lot of > > memory in separate memory blocks and wait for memory to get onlined by user > > space before continuing to add more memory blocks (to not add memory faster > > than it is getting onlined). This of course slows down the whole memory > > hotplug process. > > > > To make the job of distributions easier and to avoid udev rules that get > > more and more complicated, let's extend the mechanism provided by > > - /sys/devices/system/memory/auto_online_blocks > > - "memhp_default_state=" on the kernel cmdline > > to be able to specify also "online_movable" as well as "online_kernel" > > This patch series looks good, thanks. Since Andrew has merged it to -mm again, > I won't add my Reviewed-by to bother. JFYI, Andrew usually adds R-b or A-b tags as they are posted. -- Michal Hocko SUSE Labs