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mm: introduce a common interface for balloon pages mobility

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Memory fragmentation introduced by ballooning might reduce significantly
the number of 2MB contiguous memory blocks that can be used within a guest,
thus imposing performance penalties associated with the reduced number of
transparent huge pages that could be used by the guest workload.

This patch introduces a common interface to help a balloon driver on
making its page set movable to compaction, and thus allowing the system
to better leverage the compation efforts on memory defragmentation.

[akpm@linux-foundation.org: use PAGE_FLAGS_CHECK_AT_PREP, s/__balloon_page_flags/page_flags_cleared/, small cleanups]
[rientjes@google.com: allow balloon compaction for any system with memory compaction enabled, which is the defconfig]
Signed-off-by: Rafael Aquini <aquini@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Rafael Aquini
2012-12-11 16:02:38 -08:00
committed by Linus Torvalds
parent 252aa6f5be
commit 18468d93e5
6 changed files with 617 additions and 1 deletions
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10
include/linux/migrate.h
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@@ -11,8 +11,18 @@ typedef struct page *new_page_t(struct page *, unsigned long private, int **);
* Return values from addresss_space_operations.migratepage():
* - negative errno on page migration failure;
* - zero on page migration success;
*
* The balloon page migration introduces this special case where a 'distinct'
* return code is used to flag a successful page migration to unmap_and_move().
* This approach is necessary because page migration can race against balloon
* deflation procedure, and for such case we could introduce a nasty page leak
* if a successfully migrated balloon page gets released concurrently with
* migration's unmap_and_move() wrap-up steps.
*/
#define MIGRATEPAGE_SUCCESS 0
#define MIGRATEPAGE_BALLOON_SUCCESS 1 /* special ret code for balloon page
* sucessful migration case.
*/
#ifdef CONFIG_MIGRATION