[PATCH] mm: show node to memory section relationship with symlinks in sysfs

Gary Hade
2008-09-29T20:05:54Z

Show node to memory section relationship with symlinks in sysfs

Add /sys/devices/system/node/nodeX/memoryY symlinks for all
the memory sections located on nodeX. For example:
/sys/devices/system/node/node1/memory135 -> ../../memory/memory135
indicates that memory section 135 resides on node1.

Successfully tested with 2.6.27-rc7 source on 2-node x86_64,
2-node ppc64, and 2-node ia64 systems.

Also revises documentation to cover this change as well as updating
Documentation/ABI/testing/sysfs-devices-memory to include descriptions
of memory hotremove files 'phys_device', 'phys_index', and 'state'
that were previously not described there.

Supersedes the "mm: show memory section to node relationship in sysfs"
patch posted on 05 Sept 2008 which created node ID containing 'node'
files in /sys/devices/system/memory/memoryX instead of symlinks.
Changed from files to symlinks due to feedback that symlinks were
more consistent with the sysfs way.

Signed-off-by: Gary Hade <garyhade@us.ibm.com>
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>

---
Documentation/ABI/testing/sysfs-devices-memory | 51 ++++++++++++
Documentation/memory-hotplug.txt | 16 +++
drivers/base/memory.c | 10 ++
drivers/base/node.c | 61 +++++++++++++++
include/linux/memory.h | 4
include/linux/node.h | 11 ++
6 files changed, 146 insertions(+), 7 deletions(-)

Index: linux-2.6.27-rc5/Documentation/ABI/testing/sysfs-devices-memory
===================================================================
--- linux-2.6.27-rc5.orig/Documentation/ABI/testing/sysfs-devices-memory 2008-09-24 13:19:23.000000000 -0700
+++ linux-2.6.27-rc5/Documentation/ABI/testing/sysfs-devices-memory 2008-09-25 13:36:41.000000000 -0700
@@ -6,7 +6,6 @@
internal state of the kernel memory blocks. Files could be
added or removed dynamically to represent hot-add/remove
operations.
-
Users: hotplug memory add/remove tools
https://w3.opensource.ibm.com/projects/powerpc-utils/

@@ -19,6 +18,56 @@
This is useful for a user-level agent to determine
identify removable sections of the memory before attempting
potentially expensive hot-remove memory operation
+Users: hotplug memory remove tools
+ https://w3.opensource.ibm.com/projects/powerpc-utils/
+
+What: /sys/devices/system/memory/memoryX/phys_device
+Date: September 2008
+Contact: Badari Pulavarty <pbadari@us.ibm.com>
+Description:
+ The file /sys/devices/system/memory/memoryX/phys_device
+ is read-only and is designed to show the name of physical
+ memory device. Implementation is currently incomplete.

+What: /sys/devices/system/memory/memoryX/phys_index
+Date: September 2008
+Contact: Badari Pulavarty <pbadari@us.ibm.com>
+Description:
+ The file /sys/devices/system/memory/memoryX/phys_index
+ is read-only and contains the section ID in hexadecimal
+ which is equivalent to decimal X contained in the
+ memory section directory name.
+
+What: /sys/devices/system/memory/memoryX/state
+Date: September 2008
+Contact: Badari Pulavarty <pbadari@us.ibm.com>
+Description:
+ The file /sys/devices/system/memory/memoryX/state
+ is read-write. When read, it's contents show the
+ online/offline state of the memory section. When written,
+ root can toggle the the online/offline state of a removable
+ memory section (see removable file description above)
+ using the following commands.
+ # echo online > /sys/devices/system/memory/memoryX/state
+ # echo offline > /sys/devices/system/memory/memoryX/state
+
+ For example, if /sys/devices/system/memory/memory22/removable
+ contains a value of 1 and
+ /sys/devices/system/memory/memory22/state contains the
+ string "online" the following command can be executed by
+ by root to offline that section.
+ # echo offline > /sys/devices/system/memory/memory22/state
Users: hotplug memory remove tools
https://w3.opensource.ibm.com/projects/powerpc-utils/
+
+What: /sys/devices/system/node/nodeX/memoryY
+Date: September 2008
+Contact: Gary Hade <garyhade@us.ibm.com>
+Description:
+ When CONFIG_NUMA is enabled
+ /sys/devices/system/node/nodeX/memoryY is a symbolic link that
+ points to the corresponding /sys/devices/system/memory/memoryY
+ memory section directory. For example, the following symbolic
+ link is created for memory section 9 on node0.
+ /sys/devices/system/node/node0/memory9 -> ../../memory/memory9
+
Index: linux-2.6.27-rc5/Documentation/memory-hotplug.txt
===================================================================
--- linux-2.6.27-rc5.orig/Documentation/memory-hotplug.txt 2008-09-24 13:19:23.000000000 -0700
+++ linux-2.6.27-rc5/Documentation/memory-hotplug.txt 2008-09-25 13:36:58.000000000 -0700
@@ -124,7 +124,7 @@
This option can be kernel module too.

--------------------------------
-3 sysfs files for memory hotplug
+4 sysfs files for memory hotplug
--------------------------------
All sections have their device information under /sys/devices/system/memory as

@@ -138,11 +138,12 @@
(0x100000000 / 1Gib = 4)
This device covers address range [0x100000000 ... 0x140000000)

-Under each section, you can see 3 files.
+Under each section, you can see 4 files.

/sys/devices/system/memory/memoryXXX/phys_index
/sys/devices/system/memory/memoryXXX/phys_device
/sys/devices/system/memory/memoryXXX/state
+/sys/devices/system/memory/memoryXXX/removable

'phys_index' : read-only and contains section id, same as XXX.
'state' : read-write
@@ -150,10 +151,20 @@
at write: user can specify "online", "offline" command
'phys_device': read-only: designed to show the name of physical memory device.
This is not well implemented now.
+'removable' : read-only: contains an integer value indicating
+ whether the memory section is removable or not
+ removable. A value of 1 indicates that the memory
+ section is removable and a value of 0 indicates that
+ it is not removable.

NOTE:
These directories/files appear after physical memory hotplug phase.

+If CONFIG_NUMA is specified the
+/sys/devices/system/memory/memoryXXX memory section
+directories can also be accessed via symbolic links located in
+the /sys/devices/system/node/node* directories. For example:
+/sys/devices/system/node/node0/memory9 -> ../../memory/memory9

--------------------------------
4. Physical memory hot-add phase
@@ -365,7 +376,6 @@
- allowing memory hot-add to ZONE_MOVABLE. maybe we need some switch like
sysctl or new control file.
- showing memory section and physical device relationship.
- - showing memory section and node relationship (maybe good for NUMA)
- showing memory section is under ZONE_MOVABLE or not
- test and make it better memory offlining.
- support HugeTLB page migration and offlining.
Index: linux-2.6.27-rc5/drivers/base/memory.c
===================================================================
--- linux-2.6.27-rc5.orig/drivers/base/memory.c 2008-09-24 13:19:23.000000000 -0700
+++ linux-2.6.27-rc5/drivers/base/memory.c 2008-09-24 13:19:29.000000000 -0700
@@ -368,6 +368,13 @@
ret = mem_create_simple_file(mem, phys_device);
if (!ret)
ret = mem_create_simple_file(mem, removable);
+ if (!ret) {
+ ret = register_mem_sect_under_node(mem);
+ if (ret == -EFAULT) {
+ /* expected during boot if node not registered yet */
+ ret = 0;
+ }
+ }

return ret;
}
@@ -380,7 +387,7 @@
*
* This could be made generic for all sysdev classes.
*/
-static struct memory_block *find_memory_block(struct mem_section *section)
+struct memory_block *find_memory_block(struct mem_section *section)
{
struct kobject *kobj;
struct sys_device *sysdev;
@@ -409,6 +416,7 @@
struct memory_block *mem;

mem = find_memory_block(section);
+ unregister_mem_sect_under_node(mem);
mem_remove_simple_file(mem, phys_index);
mem_remove_simple_file(mem, state);
mem_remove_simple_file(mem, phys_device);
Index: linux-2.6.27-rc5/drivers/base/node.c
===================================================================
--- linux-2.6.27-rc5.orig/drivers/base/node.c 2008-09-24 13:19:23.000000000 -0700
+++ linux-2.6.27-rc5/drivers/base/node.c 2008-09-25 13:36:00.000000000 -0700
@@ -6,6 +6,7 @@
#include <linux/module.h>
#include <linux/init.h>
#include <linux/mm.h>
+#include <linux/memory.h>
#include <linux/node.h>
#include <linux/hugetlb.h>
#include <linux/cpumask.h>
@@ -225,6 +226,63 @@
return 0;
}

+#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
+int register_mem_sect_under_node(struct memory_block *mem_blk)
+{
+ unsigned int nid;
+
+ if (!mem_blk)
+ return -EFAULT;
+ nid = section_nr_to_nid(mem_blk->phys_index);
+ if (!node_online(nid))
+ return 0;
+ return sysfs_create_link_nowarn(&node_devices[nid].sysdev.kobj,
+ &mem_blk->sysdev.kobj, kobject_name(&mem_blk->sysdev.kobj));
+}
+
+int unregister_mem_sect_under_node(struct memory_block *mem_blk)
+{
+ unsigned int nid;
+
+ if (!mem_blk)
+ return -EFAULT;
+ nid = section_nr_to_nid(mem_blk->phys_index);
+ if (!node_online(nid))
+ return 0;
+ sysfs_remove_link(&node_devices[nid].sysdev.kobj,
+ kobject_name(&mem_blk->sysdev.kobj));
+ return 0;
+}
+
+static int link_mem_sections(int nid)
+{
+ unsigned long start_pfn = NODE_DATA(nid)->node_start_pfn;
+ unsigned long end_pfn = start_pfn + NODE_DATA(nid)->node_spanned_pages;
+ unsigned long pfn;
+ int err = 0;
+
+ for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+ unsigned long section_nr = pfn_to_section_nr(pfn);
+ struct mem_section *mem_sect;
+ struct memory_block *mem_blk;
+ int ret;
+
+ if (!present_section_nr(section_nr))
+ continue;
+ if (pfn_to_nid(pfn) != nid)
+ continue;
+ mem_sect = __nr_to_section(section_nr);
+ mem_blk = find_memory_block(mem_sect);
+ ret = register_mem_sect_under_node(mem_blk);
+ if (!err)
+ err = ret;
+ }
+ return err;
+}
+#else
+static int link_mem_sections(int nid) { return 0; }
+#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
+
int register_one_node(int nid)
{
int error = 0;
@@ -244,6 +302,9 @@
if (cpu_to_node(cpu) == nid)
register_cpu_under_node(cpu, nid);
}
+
+ /* link memory sections under this node */
+ error = link_mem_sections(nid);
}

return error;
Index: linux-2.6.27-rc5/include/linux/memory.h
===================================================================
--- linux-2.6.27-rc5.orig/include/linux/memory.h 2008-09-24 13:19:23.000000000 -0700
+++ linux-2.6.27-rc5/include/linux/memory.h 2008-09-24 13:19:29.000000000 -0700
@@ -84,9 +84,9 @@
extern int memory_dev_init(void);
extern int remove_memory_block(unsigned long, struct mem_section *, int);
extern int memory_notify(unsigned long val, void *v);
+extern struct memory_block *find_memory_block(struct mem_section *);
#define CONFIG_MEM_BLOCK_SIZE (PAGES_PER_SECTION<<PAGE_SHIFT)
-
-
+#define section_nr_to_nid(section_nr) pfn_to_nid(section_nr_to_pfn(section_nr))
#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */

#ifdef CONFIG_MEMORY_HOTPLUG
Index: linux-2.6.27-rc5/include/linux/node.h
===================================================================
--- linux-2.6.27-rc5.orig/include/linux/node.h 2008-09-24 13:19:23.000000000 -0700
+++ linux-2.6.27-rc5/include/linux/node.h 2008-09-24 13:19:29.000000000 -0700
@@ -26,6 +26,7 @@
struct sys_device sysdev;
};

+struct memory_block;
extern struct node node_devices[];

extern int register_node(struct node *, int, struct node *);
@@ -35,6 +36,8 @@
extern void unregister_one_node(int nid);
extern int register_cpu_under_node(unsigned int cpu, unsigned int nid);
extern int unregister_cpu_under_node(unsigned int cpu, unsigned int nid);
+extern int register_mem_sect_under_node(struct memory_block *mem_blk);
+extern int unregister_mem_sect_under_node(struct memory_block *mem_blk);
#else
static inline int register_one_node(int nid)
{
@@ -52,6 +55,14 @@
{
return 0;
}
+static inline int register_mem_sect_under_node(struct memory_block *mem_blk)
+{
+ return 0;
+}
+static inline int unregister_mem_sect_under_node(struct memory_block *mem_blk)
+{
+ return 0;
+}
#endif

#define to_node(sys_device) container_of(sys_device, struct node, sysdev)