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 <haicheng.li@xxxxxxxxxxxxxxx> Signed-off-by: Shaohui Zheng <shaohui.zheng@xxxxxxxxx> --- 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..e65ecfe --- /dev/null +++ b/Documentation/x86/x86_64/numa_hotplug_emulator.txt @@ -0,0 +1,85 @@ +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 + +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 <haicheng.li@xxxxxxxxxxxxxxx> +- Shaohui Zheng <shaohui.zheng@xxxxxxxxx> + May 2010 + -- Thanks & Regards, Shaohui
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 <haicheng.li@xxxxxxxxxxxxxxx> Signed-off-by: Shaohui Zheng <shaohui.zheng@xxxxxxxxx> --- 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..e65ecfe --- /dev/null +++ b/Documentation/x86/x86_64/numa_hotplug_emulator.txt @@ -0,0 +1,85 @@ +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 + +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 <haicheng.li@xxxxxxxxxxxxxxx> +- Shaohui Zheng <shaohui.zheng@xxxxxxxxx> + May 2010 +