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author | Yasunori Goto <y-goto@jp.fujitsu.com> | 2007-10-21 16:41:36 -0700 |
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committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-10-22 08:13:17 -0700 |
commit | 10020ca246c55744dad815ad4f15e1f488ca55a8 (patch) | |
tree | f848f3c6180b043abc7560e366fd634c468cfa41 | |
parent | a24e785111a32ccb7cebafd24b1b1cb474ea8e5d (diff) | |
download | linux-stable-10020ca246c55744dad815ad4f15e1f488ca55a8.tar.gz linux-stable-10020ca246c55744dad815ad4f15e1f488ca55a8.tar.bz2 linux-stable-10020ca246c55744dad815ad4f15e1f488ca55a8.zip |
memory hotplug: document the memory hotplug notifier
Add description about event notification callback routine to the document
Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r-- | Documentation/memory-hotplug.txt | 58 |
1 files changed, 55 insertions, 3 deletions
diff --git a/Documentation/memory-hotplug.txt b/Documentation/memory-hotplug.txt index 5fbcc22c98e9..168117bd6ee8 100644 --- a/Documentation/memory-hotplug.txt +++ b/Documentation/memory-hotplug.txt @@ -2,7 +2,8 @@ Memory Hotplug ============== -Last Updated: Jul 28 2007 +Created: Jul 28 2007 +Add description of notifier of memory hotplug Oct 11 2007 This document is about memory hotplug including how-to-use and current status. Because Memory Hotplug is still under development, contents of this text will @@ -24,7 +25,8 @@ be changed often. 6.1 Memory offline and ZONE_MOVABLE 6.2. How to offline memory 7. Physical memory remove -8. Future Work List +8. Memory hotplug event notifier +9. Future Work List Note(1): x86_64's has special implementation for memory hotplug. This text does not describe it. @@ -307,8 +309,58 @@ Need more implementation yet.... - Notification completion of remove works by OS to firmware. - Guard from remove if not yet. +-------------------------------- +8. Memory hotplug event notifier +-------------------------------- +Memory hotplug has event notifer. There are 6 types of notification. + +MEMORY_GOING_ONLINE + Generated before new memory becomes available in order to be able to + prepare subsystems to handle memory. The page allocator is still unable + to allocate from the new memory. + +MEMORY_CANCEL_ONLINE + Generated if MEMORY_GOING_ONLINE fails. + +MEMORY_ONLINE + Generated when memory has succesfully brought online. The callback may + allocate pages from the new memory. + +MEMORY_GOING_OFFLINE + Generated to begin the process of offlining memory. Allocations are no + longer possible from the memory but some of the memory to be offlined + is still in use. The callback can be used to free memory known to a + subsystem from the indicated memory section. + +MEMORY_CANCEL_OFFLINE + Generated if MEMORY_GOING_OFFLINE fails. Memory is available again from + the section that we attempted to offline. + +MEMORY_OFFLINE + Generated after offlining memory is complete. + +A callback routine can be registered by + hotplug_memory_notifier(callback_func, priority) + +The second argument of callback function (action) is event types of above. +The third argument is passed by pointer of struct memory_notify. + +struct memory_notify { + unsigned long start_pfn; + unsigned long nr_pages; + int status_cahnge_nid; +} + +start_pfn is start_pfn of online/offline memory. +nr_pages is # of pages of online/offline memory. +status_change_nid is set node id when N_HIGH_MEMORY of nodemask is (will be) +set/clear. It means a new(memoryless) node gets new memory by online and a +node loses all memory. If this is -1, then nodemask status is not changed. +If status_changed_nid >= 0, callback should create/discard structures for the +node if necessary. + -------------- -8. Future Work +9. Future Work -------------- - allowing memory hot-add to ZONE_MOVABLE. maybe we need some switch like sysctl or new control file. |