Re: [RFC][PATCH 0/9] extend hugepage migration

From: Simon Jeons
Date: Tue Mar 19 2013 - 19:43:54 EST

Hi Naoya,
On 02/22/2013 03:41 AM, Naoya Horiguchi wrote:

Hugepage migration is now available only for soft offlining (moving
data on the half corrupted page to another page to save the data).
But it's also useful some other users of page migration, so this
patchset tries to extend some of such users to support hugepage.

The targets of this patchset are NUMA related system calls (i.e.
migrate_pages(2), move_pages(2), and mbind(2)), and memory hotplug.
This patchset does not extend page migration in memory compaction,
because I think that users of memory compaction mainly expect to
construct thp by arranging raw pages but hugepage migration doesn't
help it.
CMA, another user of page migration, can have benefit from hugepage
migration, but is not enabled to support it now. This is because
I've never used CMA and need to learn more to extend and/or test
hugepage migration in CMA. I'll add this in later version if it
becomes ready, or will post as a separate patchset.

Hugepage migration of 1GB hugepage is not enabled for now, because
I'm not sure whether users of 1GB hugepage really want it.
We need to spare free hugepage in order to do migration, but I don't
think that users want to 1GB memory to idle for that purpose
(currently we can't expand/shrink 1GB hugepage pool after boot).

Could you review and give me some comments/feedbacks?

Naoya Horiguchi
Easy patch access:

Test code:

git clone git@xxxxxxxxxx:Naoya-Horiguchi/test_hugepage_migration_extension.git
Cloning into test_hugepage_migration_extension...
Permission denied (publickey).
fatal: The remote end hung up unexpectedly

Naoya Horiguchi (9):
migrate: add migrate_entry_wait_huge()
migrate: make core migration code aware of hugepage
soft-offline: use migrate_pages() instead of migrate_huge_page()
migrate: clean up migrate_huge_page()
migrate: enable migrate_pages() to migrate hugepage
migrate: enable move_pages() to migrate hugepage
mbind: enable mbind() to migrate hugepage
memory-hotplug: enable memory hotplug to handle hugepage
remove /proc/sys/vm/hugepages_treat_as_movable

Documentation/sysctl/vm.txt | 16 ------
include/linux/hugetlb.h | 25 ++++++++--
include/linux/mempolicy.h | 2 +-
include/linux/migrate.h | 12 ++---
include/linux/swapops.h | 4 ++
kernel/sysctl.c | 7 ---
mm/hugetlb.c | 98 ++++++++++++++++++++++++++++--------
mm/memory-failure.c | 20 ++++++--
mm/memory.c | 6 ++-
mm/memory_hotplug.c | 51 +++++++++++++++----
mm/mempolicy.c | 61 +++++++++++++++--------
mm/migrate.c | 119 ++++++++++++++++++++++++++++++--------------
mm/page_alloc.c | 12 +++++
mm/page_isolation.c | 5 ++
14 files changed, 311 insertions(+), 127 deletions(-)

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