diff options
| author | Brice Goglin <Brice.Goglin@inria.fr> | 2008-10-19 07:27:15 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-10-20 19:52:33 +0400 |
| commit | e78bbfa8262424417a29349a8064a535053912b9 (patch) | |
| tree | dc1f1cdd4390b3f817a2d3a2835c11eb3b41b3ea /mm/migrate.c | |
| parent | de7f0cba96786cf9ec9da4532c1b25f733da9b6f (diff) | |
| download | linux-e78bbfa8262424417a29349a8064a535053912b9.tar.xz | |
mm: stop returning -ENOENT from sys_move_pages() if nothing got migrated
A patchset reworking sys_move_pages(). It removes the possibly large
vmalloc by using multiple chunks when migrating large buffers. It also
dramatically increases the throughput for large buffers since the lookup
in new_page_node() is now limited to a single chunk, causing the quadratic
complexity to have a much slower impact. There is no need to use any
radix-tree-like structure to improve this lookup.
sys_move_pages() duration on a 4-quadcore-opteron 2347HE (1.9Gz),
migrating between nodes #2 and #3:
length move_pages (us) move_pages+patch (us)
4kB 126 98
40kB 198 168
400kB 963 937
4MB 12503 11930
40MB 246867 11848
Patches #1 and #4 are the important ones:
1) stop returning -ENOENT from sys_move_pages() if nothing got migrated
2) don't vmalloc a huge page_to_node array for do_pages_stat()
3) extract do_pages_move() out of sys_move_pages()
4) rework do_pages_move() to work on page_sized chunks
5) move_pages: no need to set pp->page to ZERO_PAGE(0) by default
This patch:
There is no point in returning -ENOENT from sys_move_pages() if all pages
were already on the right node, while we return 0 if only 1 page was not.
Most application don't know where their pages are allocated, so it's not
an error to try to migrate them anyway.
Just return 0 and let the status array in user-space be checked if the
application needs details.
It will make the upcoming chunked-move_pages() support much easier.
Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>
Acked-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/migrate.c')
| -rw-r--r-- | mm/migrate.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/mm/migrate.c b/mm/migrate.c index 6802a7a3dfec..f233519f0453 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -896,11 +896,10 @@ set_status: pp->status = err; } + err = 0; if (!list_empty(&pagelist)) err = migrate_pages(&pagelist, new_page_node, (unsigned long)pm); - else - err = -ENOENT; up_read(&mm->mmap_sem); return err; |