Fragmentation avoidance in the kernel depends on reclaimable and movable allocations being marked-up at page allocation time. Reclaimable allocations refer to slab caches such as inode caches which can be reclaimed although not necessarily in a targetted fashion. Movable pages are those pages that can be moved to backing storage (during page reclaim) or migrated. When testing against XFS, it was noticed that large page allocation rates against XFS were far lower than expected in comparison to ext3. Investigation showed that buffer pages allocated by XFS are placed on the LRU but not marked __GFP_MOVABLE at allocation time. This patch updates xb_to_gfp() to specify __GFP_MOVABLE and is correct iff all pages allocated from a mask derived from xb_to_gfp() are guaranteed to be movable be it via page reclaim or page migration. It needs an XFS expert to make that determination but when applied, huge page allocation success rates are similar to those seen on tests backed by ext3. Signed-off-by: Mel Gorman <mel@xxxxxxxxx> --- fs/xfs/linux-2.6/xfs_buf.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c index ea79072..93f3fb0 100644 --- a/fs/xfs/linux-2.6/xfs_buf.c +++ b/fs/xfs/linux-2.6/xfs_buf.c @@ -67,7 +67,7 @@ struct workqueue_struct *xfsconvertd_workqueue; #define xb_to_gfp(flags) \ ((((flags) & XBF_READ_AHEAD) ? __GFP_NORETRY : \ - ((flags) & XBF_DONT_BLOCK) ? GFP_NOFS : GFP_KERNEL) | __GFP_NOWARN) + ((flags) & XBF_DONT_BLOCK) ? GFP_NOFS : GFP_KERNEL) | __GFP_NOWARN | __GFP_MOVABLE) #define xb_to_km(flags) \ (((flags) & XBF_DONT_BLOCK) ? KM_NOFS : KM_SLEEP) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>