The patch titled
mm: stop returning -ENOENT from sys_move_pages() if nothing got migrated
has been removed from the -mm tree. Its filename was
mm-stop-returning-enoent-from-sys_move_pages-if-nothing-got-migrated.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: mm: stop returning -ENOENT from sys_move_pages() if nothing got migrated
From: Brice Goglin <Brice.Goglin@xxxxxxxx>
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@xxxxxxxx>
Acked-by: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx>
Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/migrate.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff -puN mm/migrate.c~mm-stop-returning-enoent-from-sys_move_pages-if-nothing-got-migrated mm/migrate.c
--- a/mm/migrate.c~mm-stop-returning-enoent-from-sys_move_pages-if-nothing-got-migrated
+++ a/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;
_
Patches currently in -mm which might be from Brice.Goglin@xxxxxxxx are
origin.patch
mm-rework-do_pages_move-to-work-on-page_sized-chunks.patch
mm-move_pages-no-need-to-set-pp-page-to-zero_page0-by-default.patch
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