From b969c4ab9f182a6e1b2a0848be349f99714947b0 Mon Sep 17 00:00:00 2001
From: Mel Gorman <mgorman@suse.de>
Date: Thu, 12 Jan 2012 17:19:34 -0800
Subject: mm: compaction: determine if dirty pages can be migrated without
blocking within ->migratepage
Asynchronous compaction is used when allocating transparent hugepages to
avoid blocking for long periods of time. Due to reports of stalling,
there was a debate on disabling synchronous compaction but this severely
impacted allocation success rates. Part of the reason was that many dirty
pages are skipped in asynchronous compaction by the following check;
if (PageDirty(page) && !sync &&
mapping->a_ops->migratepage != migrate_page)
rc = -EBUSY;
This skips over all mapping aops using buffer_migrate_page() even though
it is possible to migrate some of these pages without blocking. This
patch updates the ->migratepage callback with a "sync" parameter. It is
the responsibility of the callback to fail gracefully if migration would
block.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Andy Isaacson <adi@hexapodia.org>
Cc: Nai Xia <nai.xia@gmail.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
fs/nfs/internal.h | 2 +-
fs/nfs/write.c | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)
(limited to 'fs/nfs')
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 5ee92538b063..114398a15830 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -332,7 +332,7 @@ void nfs_commit_release_pages(struct nfs_write_data *data);
#ifdef CONFIG_MIGRATION
extern int nfs_migrate_page(struct address_space *,
- struct page *, struct page *);
+ struct page *, struct page *, bool);
#else
#define nfs_migrate_page NULL
#endif
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 0c3885255f97..889e98bc5a21 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1688,7 +1688,7 @@ out_error:
#ifdef CONFIG_MIGRATION
int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
- struct page *page)
+ struct page *page, bool sync)
{
/*
* If PagePrivate is set, then the page is currently associated with
@@ -1703,7 +1703,7 @@ int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
nfs_fscache_release_page(page, GFP_KERNEL);
- return migrate_page(mapping, newpage, page);
+ return migrate_page(mapping, newpage, page, sync);
}
#endif
--
cgit