This patch enables reader optimistic spinning for inodes that are
under a DAX-based mount point.
On a 4-socket Haswell machine running on a 4.7-rc1 tip-based kernel,
the fio test with multithreaded randrw and randwrite tests on the
same file on a XFS partition on top of a NVDIMM with DAX were run,
the aggregated bandwidths before and after the patch were as follows:
Test BW before patch BW after patch % change
---- --------------- -------------- --------
randrw 1352 MB/s 2164 MB/s +60%
randwrite 1710 MB/s 2550 MB/s +49%
Signed-off-by: Waiman Long <Waiman.Long@xxxxxxx>
---
fs/xfs/xfs_icache.c | 9 +++++++++
1 files changed, 9 insertions(+), 0 deletions(-)
diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index 99ee6ee..09f284f 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -71,6 +71,15 @@ xfs_inode_alloc(
mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", ip->i_ino);
+ /*
+ * Enable reader spinning for DAX nount point
+ */
+ if (mp->m_flags & XFS_MOUNT_DAX) {
+ rwsem_set_rspin_threshold(&ip->i_iolock.mr_lock);
+ rwsem_set_rspin_threshold(&ip->i_mmaplock.mr_lock);
+ rwsem_set_rspin_threshold(&ip->i_lock.mr_lock);
+ }
+
/* initialise the xfs inode */
ip->i_ino = ino;
ip->i_mount = mp;
--
1.7.1
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