[XFS] On machines with more than 8 cpus, when running parallel I/O
threads, the incore superblock lock becomes the limiting factor for
buffered write throughput. Make the contended fields in the incore
superblock use per-cpu counters so that there is no global lock to limit
scalability.
SGI-PV: 946630
SGI-Modid: xfs-linux-melb:xfs-kern:25106a
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>
diff --git a/fs/xfs/linux-2.6/xfs_linux.h b/fs/xfs/linux-2.6/xfs_linux.h
index 67389b7..377a9f5 100644
--- a/fs/xfs/linux-2.6/xfs_linux.h
+++ b/fs/xfs/linux-2.6/xfs_linux.h
@@ -100,6 +100,11 @@
*/
#undef HAVE_REFCACHE /* reference cache not needed for NFS in 2.6 */
#define HAVE_SENDFILE /* sendfile(2) exists in 2.6, but not in 2.4 */
+#if CONFIG_SMP
+#define HAVE_PERCPU_SB /* per cpu superblock counters are a 2.6 feature */
+#else
+#undef HAVE_PERCPU_SB /* per cpu superblock counters are a 2.6 feature */
+#endif
/*
* State flag for unwritten extent buffers.
