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From: Shaohui Zheng on 13 May 2010 08:00
Userland interface to hotplug-add fake offlined nodes.

Add a sysfs entry "probe" under /sys/devices/system/node/:

- 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

Signed-off-by: Haicheng Li <haicheng.li(a)linux.intel.com>
Signed-off-by: Shaohui Zheng <shaohui.zheng(a)intel.com>
---
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 9458685..2c078c8 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1214,6 +1214,20 @@ config NUMA_EMU
into virtual nodes when booted with "numa=fake=N", where N is the
number of nodes. This is only useful for debugging.

+config NUMA_HOTPLUG_EMU
+ bool "NUMA hotplug emulator"
+ depends on X86_64 && NUMA && HOTPLUG
+ ---help---
+
+config NODE_HOTPLUG_EMU
+ bool "Node hotplug emulation"
+ depends on NUMA_HOTPLUG_EMU && MEMORY_HOTPLUG
+ ---help---
+ Enable Node hotplug emulation. The machine will be setup with
+ hidden virtual nodes when booted with "numa=hide=N*size", where
+ N is the number of hidden nodes, size is the memory size per
+ hidden node. This is only useful for debugging.
+
config NODES_SHIFT
int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
range 1 10
diff --git a/drivers/base/node.c b/drivers/base/node.c
index 057979a..a0be257 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -535,6 +535,26 @@ void unregister_one_node(int nid)
unregister_node(&node_devices[nid]);
}

+#ifdef CONFIG_NODE_HOTPLUG_EMU
+static ssize_t store_nodes_probe(struct sysdev_class *class,
+ struct sysdev_class_attribute *attr,
+ const char *buf, size_t count)
+{
+ long nid;
+ int ret;
+
+ strict_strtol(buf, 0, &nid);
+ if (nid < 0 || nid > nr_node_ids - 1) {
+ printk(KERN_ERR "Invalid NUMA node id: %d (0 <= nid < %d).\n",
+ nid, nr_node_ids);
+ return -EPERM;
+ }
+ hotadd_hidden_nodes(nid);
+
+ return count;
+}
+#endif
+
/*
* node states attributes
*/
@@ -563,26 +583,35 @@ static ssize_t show_node_state(struct sysdev_class *class,
return print_nodes_state(na->state, buf);
}

-#define _NODE_ATTR(name, state) \
+#define _NODE_ATTR_RO(name, state) \
{ _SYSDEV_CLASS_ATTR(name, 0444, show_node_state, NULL), state }

+#define _NODE_ATTR_RW(name, store_func, state) \
+ { _SYSDEV_CLASS_ATTR(name, 0644, show_node_state, store_func), state }
+
static struct node_attr node_state_attr[] = {
- _NODE_ATTR(possible, N_POSSIBLE),
- _NODE_ATTR(online, N_ONLINE),
- _NODE_ATTR(has_normal_memory, N_NORMAL_MEMORY),
- _NODE_ATTR(has_cpu, N_CPU),
+ [N_POSSIBLE] = _NODE_ATTR_RO(possible, N_POSSIBLE),
+#ifdef CONFIG_NODE_HOTPLUG_EMU
+ [N_HIDDEN] = _NODE_ATTR_RW(probe, store_nodes_probe, N_HIDDEN),
+#endif
+ [N_ONLINE] = _NODE_ATTR_RO(online, N_ONLINE),
+ [N_NORMAL_MEMORY] = _NODE_ATTR_RO(has_normal_memory, N_NORMAL_MEMORY),
#ifdef CONFIG_HIGHMEM
- _NODE_ATTR(has_high_memory, N_HIGH_MEMORY),
+ [N_HIGH_MEMORY] = _NODE_ATTR_RO(has_high_memory, N_HIGH_MEMORY),
#endif
+ [N_CPU] = _NODE_ATTR_RO(has_cpu, N_CPU),
};

static struct sysdev_class_attribute *node_state_attrs[] = {
- &node_state_attr[0].attr,
- &node_state_attr[1].attr,
- &node_state_attr[2].attr,
- &node_state_attr[3].attr,
+ &node_state_attr[N_POSSIBLE].attr,
+#ifdef CONFIG_NODE_HOTPLUG_EMU
+ &node_state_attr[N_HIDDEN].attr,
+#endif
+ &node_state_attr[N_ONLINE].attr,
+ &node_state_attr[N_NORMAL_MEMORY].attr,
+ &node_state_attr[N_CPU].attr,
#ifdef CONFIG_HIGHMEM
- &node_state_attr[4].attr,
+ &node_state_attr[N_HIGH_MEMORY].attr,
#endif
NULL
};
--
Thanks & Regards,
Shaohui

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