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Date: Mon, 6 Dec 2010 07:50:57 +0800
From: Shaohui Zheng <shaohui.zheng@...ux.intel.com>
To: David Rientjes <rientjes@...gle.com>
Cc: Shaohui Zheng <shaohui.zheng@...el.com>,
Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, haicheng.li@...ux.intel.com,
lethal@...ux-sh.org, ak@...ux.intel.com, dave@...ux.vnet.ibm.com,
Greg Kroah-Hartman <gregkh@...e.de>,
Haicheng Li <haicheng.li@...el.com>
Subject: Re: [patch 7/7, v7] NUMA Hotplug Emulator: Implement
mem_hotplug/add_memory debugfs interface
On Thu, Dec 02, 2010 at 03:37:03PM -0800, David Rientjes wrote:
> On Thu, 2 Dec 2010, shaohui.zheng@...el.com wrote:
>
> > From: Shaohui Zheng <shaohui.zheng@...el.com>
> >
> > Add mem_hotplug/add_memory interface to support to memory hotplug emulation.
> > the reserved memory can be added into desired node with this interface.
> >
> > Add a memory section(128M) to node 3(boots with mem=1024m)
> >
> > echo 0x40000000,3 > mem_hotplug/add_memory
> >
> > And more we make it friendly, it is possible to add memory to do
> >
> > echo 3g > mem_hotplug/add_memory
> > echo 1024m,3 > mem_hotplug/add_memory
> >
> > Another format suggested by Dave Hansen:
> >
> > echo physical_address=0x40000000 numa_node=3 > mem_hotplug/add_memory
> >
> > it is more explicit to show meaning of the parameters.
> >
>
> NACK, we don't need such convoluted definitions if debugfs were extended
> with per-node triggers to add_memory as I suggested in v6 of your
> proposal:
>
> /sys/kernel/debug/mem_hotplug/add_node (already exists)
> /sys/kernel/debug/mem_hotplug/node0/add_memory
> /sys/kernel/debug/mem_hotplug/node1/add_memory
> ...
>
> You can then write a physical starting address to the add_memory files to
> hotadd memory to a node other than the one to which it has physical
> affinity. This is much more extendable if we add additional per-node
> triggers later.
>
> It would also be helpful if you were to reach consensus on the matters
> under discussion before posting a new version of your patchset everyday.
After consider your proposal again, the new add_memory interface under each
nodes follow the rule "one file one parameter" better. it make the parser
much simpler.
I work out a patch for this proposal, and it works on my side.
Any more comments?
Subject: NUMA Hotplug Emulator: Implement add_memory debugfs interface
From: Shaohui Zheng <shaohui.zheng@...el.com>
Add add_memory interface to support to memory hotplug emulation for each online
node under debugfs. The reserved memory can be added into desired node with
this interface.
The layout on debufs:
mem_hotplug/node0/add_memory
mem_hotplug/node1/add_memory
mem_hotplug/node2/add_memory
...
Add a memory section(128M) to node 3(boots with mem=1024m)
echo 0x40000000 > mem_hotplug/node3/add_memory
And more we make it friendly, it is possible to add memory to do
echo 1024m > mem_hotplug/node3/add_memory
CC: David Rientjes <rientjes@...gle.com>
CC: Dave Hansen <dave@...ux.vnet.ibm.com>
Signed-off-by: Shaohui Zheng <shaohui.zheng@...el.com>
Signed-off-by: Haicheng Li <haicheng.li@...el.com>
Signed-off-by: Shaohui Zheng <shaohui.zheng@...el.com>
---
Index: linux-hpe4/mm/memory_hotplug.c
===================================================================
--- linux-hpe4.orig/mm/memory_hotplug.c 2010-12-02 12:35:31.557622002 +0800
+++ linux-hpe4/mm/memory_hotplug.c 2010-12-06 07:30:36.067622001 +0800
@@ -930,6 +930,80 @@
static struct dentry *memhp_debug_root;
+#ifdef CONFIG_ARCH_MEMORY_PROBE
+
+static ssize_t add_memory_store(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ u64 phys_addr = 0;
+ int nid = file->private_data - NULL;
+ int ret;
+
+ phys_addr = simple_strtoull(buf, NULL, 0);
+ printk(KERN_INFO "Add a memory section to node: %d.\n", nid);
+ phys_addr = memparse(buf, NULL);
+ ret = add_memory(nid, phys_addr, PAGES_PER_SECTION << PAGE_SHIFT);
+
+ if (ret)
+ count = ret;
+
+ return count;
+}
+
+static int add_memory_open(struct inode *inode, struct file *file)
+{
+ file->private_data = inode->i_private;
+ return 0;
+}
+
+static const struct file_operations add_memory_file_ops = {
+ .open = add_memory_open,
+ .write = add_memory_store,
+ .llseek = generic_file_llseek,
+};
+
+/*
+ * Create add_memory debugfs entry under specified node
+ */
+static int debugfs_create_add_memory_entry(int nid)
+{
+ char buf[32];
+ static struct dentry *node_debug_root;
+
+ snprintf(buf, sizeof(buf), "node%d", nid);
+ node_debug_root = debugfs_create_dir(buf, memhp_debug_root);
+
+ /* the nid information was represented by the offset of pointer(NULL+nid) */
+ if (!debugfs_create_file("add_memory", S_IWUSR, node_debug_root,
+ NULL + nid, &add_memory_file_ops))
+ return -ENOMEM;
+
+ return 0;
+}
+
+static int __init memory_debug_init(void)
+{
+ int nid;
+
+ if (!memhp_debug_root)
+ memhp_debug_root = debugfs_create_dir("mem_hotplug", NULL);
+ if (!memhp_debug_root)
+ return -ENOMEM;
+
+ for_each_online_node(nid)
+ debugfs_create_add_memory_entry(nid);
+
+ return 0;
+}
+
+module_init(memory_debug_init);
+#else
+static debugfs_create_add_memory_entry(int nid)
+{
+ return 0;
+}
+#endif /* CONFIG_ARCH_MEMORY_PROBE */
+
static ssize_t add_node_store(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
@@ -960,6 +1034,8 @@
return -ENOMEM;
ret = add_memory(nid, start, size);
+
+ debugfs_create_add_memory_entry(nid);
return ret ? ret : count;
}
Index: linux-hpe4/Documentation/memory-hotplug.txt
===================================================================
--- linux-hpe4.orig/Documentation/memory-hotplug.txt 2010-12-02 12:35:31.557622002 +0800
+++ linux-hpe4/Documentation/memory-hotplug.txt 2010-12-06 07:39:36.007622000 +0800
@@ -19,6 +19,7 @@
4.1 Hardware(Firmware) Support
4.2 Notify memory hot-add event by hand
4.3 Node hotplug emulation
+ 4.4 Memory hotplug emulation
5. Logical Memory hot-add phase
5.1. State of memory
5.2. How to online memory
@@ -239,6 +240,29 @@
Once the new node has been added, it is possible to online the memory by
toggling the "state" of its memory section(s) as described in section 5.1.
+4.4 Memory hotplug emulation
+------------
+With debugfs, it is possible to test memory hotplug with software method, we
+can add memory section to desired node with add_memory interface. It is a much
+more powerful interface than "probe" described in section 4.2.
+
+There is an add_memory interface for each online node at the debugfs mount
+point.
+ mem_hotplug/node0/add_memory
+ mem_hotplug/node1/add_memory
+ mem_hotplug/node2/add_memory
+ ...
+
+Add a memory section(128M) to node 3(boots with mem=1024m)
+
+ echo 0x40000000 > mem_hotplug/node3/add_memory
+
+And more we make it friendly, it is possible to add memory to do
+
+ echo 1024m > mem_hotplug/node3/add_memory
+
+Once the new memory section has been added, it is possible to online the memory
+by toggling the "state" described in section 5.1.
------------------------------
5. Logical Memory hot-add phase
--
Thanks & Regards,
Shaohui
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