Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755399Ab0KMHi0 (ORCPT ); Sat, 13 Nov 2010 02:38:26 -0500 Received: from mga14.intel.com ([143.182.124.37]:54488 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753837Ab0KMHiZ (ORCPT ); Sat, 13 Nov 2010 02:38:25 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.59,191,1288594800"; d="scan'208";a="348236826" Date: Sat, 13 Nov 2010 14:17:21 +0800 From: Shaohui Zheng To: linux-kernel@vger.kernel.org Subject: [v2,8/8] NUMA Hotplug emulator Message-ID: <20101113061721.GR32501@shaohui> Mail-Followup-To: linux-kernel@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3507 Lines: 112 From: Shaohui Zheng Subject: Doc/x86_64: documentation of NUMA hotplug emulator add a text file Documentation/x86/x86_64/numa_hotplug_emulator.txt to explain the usage for the hotplug emulator. Signed-off-by: Haicheng Li Signed-off-by: Shaohui Zheng --- diff --git a/Documentation/x86/x86_64/numa_hotplug_emulator.txt b/Documentation/x86/x86_64/numa_hotplug_emulator.txt new file mode 100644 index 0000000..c6bdb2c --- /dev/null +++ b/Documentation/x86/x86_64/numa_hotplug_emulator.txt @@ -0,0 +1,87 @@ +NUMA Hotplug Emulator for x86 +--------------------------------------------------- + +NUMA hotplug emulator is able to emulate NUMA Node Hotplug +thru a pure software way. It intends to help people easily debug +and test node/cpu/memory hotplug related stuff on a +none-numa-hotplug-support machine, even a UMA machine and virtual +environment. + +1) Node hotplug emulation: + +The emulator firstly hides RAM via E820 table, and then it can +fake offlined nodes with the hidden RAM. + +After system bootup, user is able to hotplug-add these offlined +nodes, which is just similar to a real hotplug hardware behavior. + +Using boot option "numa=hide=N*size" to fake offlined nodes: + - N is the number of hidden nodes + - size is the memory size (in MB) per hidden node. + +There is a sysfs entry "probe" under /sys/devices/system/node/ for user +to hotplug the fake offlined nodes: + + - to show all fake offlined nodes: + $ cat /sys/devices/system/node/probe + + - to hotadd a fake offlined node, e.g. nodeid is N: + $ echo N > /sys/devices/system/node/probe + +2) CPU hotplug emulation: + +The emulator reserve CPUs throu grub parameter, the reserved CPUs can be +hot-add/hot-remove in software method, it emulates the procuess of physical +cpu hotplug. + + - to hide CPUs + - Using boot option "maxcpus=N" hide CPUs + N is the number of initialize CPUs + - Using boot option "cpu_hpe=on" to enable cpu hotplug emulation + when cpu_hpe is enabled, the rest CPUs will not be initialized + + - to hot-add CPU to node + $ echo nid > cpu/probe + + - to hot-remove CPU + $ echo nid > cpu/release + +3) Memory hotplug emulation: + +The emulator reserve memory before OS booting, the reserved memory region +is remove from e820 table, and they can be hot-added via the probe interface, +this interface was extend to support add memory to the specified node, It +maintains backwards compatibility. + +The difficulty of Memory Release is well-known, we have no plan for it until now. + + - reserve memory throu grub parameter + mem=1024m + + - add a memory section to node 3 + $ echo 0x40000000,3 > memory/probe + OR + $ echo 1024m,3 > memory/probe + OR + $ echo "physical_address=0x40000000 numa_node=3" > memory/probe + +4) Script for hotplug testing + +These scripts provides convenience when we hot-add memory/cpu in batch. + +- Online all pages: +for m in /sys/devices/system/memory/memory*; +do + echo online > $m/state; +done + +- CPU Online: +for c in /sys/devices/system/cpu/cpu*; +do + echo 1 > $c/online; +done + +- Haicheng Li +- Shaohui Zheng + May 2010 + -- Thanks & Regards, Shaohui -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/