[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/xfs_mount.h b/fs/xfs/xfs_mount.h
index 4c9817a..7cca511 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -267,6 +267,32 @@
#define XFS_IODONE(vfsp) \
(*(mp)->m_io_ops.xfs_iodone)(vfsp)
+#ifdef HAVE_PERCPU_SB
+
+/*
+ * Valid per-cpu incore superblock counters. Note that if you add new counters,
+ * you may need to define new counter disabled bit field descriptors as there
+ * are more possible fields in the superblock that can fit in a bitfield on a
+ * 32 bit platform. The XFS_SBS_* values for the current current counters just
+ * fit.
+ */
+typedef struct xfs_icsb_cnts {
+ uint64_t icsb_fdblocks;
+ uint64_t icsb_ifree;
+ uint64_t icsb_icount;
+ spinlock_t icsb_lock;
+} xfs_icsb_cnts_t;
+
+#define XFS_ICSB_SB_LOCKED (1 << 0) /* sb already locked */
+#define XFS_ICSB_LAZY_COUNT (1 << 1) /* accuracy not needed */
+
+extern int xfs_icsb_init_counters(struct xfs_mount *);
+extern void xfs_icsb_sync_counters_lazy(struct xfs_mount *);
+
+#else
+#define xfs_icsb_init_counters(mp) (0)
+#define xfs_icsb_sync_counters_lazy(mp) do { } while (0)
+#endif
typedef struct xfs_mount {
bhv_desc_t m_bhv; /* vfs xfs behavior */
@@ -372,6 +398,10 @@
struct xfs_qmops m_qm_ops; /* vector of XQM ops */
struct xfs_ioops m_io_ops; /* vector of I/O ops */
atomic_t m_active_trans; /* number trans frozen */
+#ifdef HAVE_PERCPU_SB
+ xfs_icsb_cnts_t *m_sb_cnts; /* per-cpu superblock counters */
+ unsigned long m_icsb_counters; /* disabled per-cpu counters */
+#endif
} xfs_mount_t;
/*
@@ -409,6 +439,8 @@
#define XFS_MOUNT_DIRSYNC (1ULL << 21) /* synchronous directory ops */
#define XFS_MOUNT_COMPAT_IOSIZE (1ULL << 22) /* don't report large preferred
* I/O size in stat() */
+#define XFS_MOUNT_NO_PERCPU_SB (1ULL << 23) /* don't use per-cpu superblock
+ counters */
/*
@@ -546,6 +578,8 @@
extern int xfs_unmountfs_writesb(xfs_mount_t *);
extern int xfs_unmount_flush(xfs_mount_t *, int);
extern int xfs_mod_incore_sb(xfs_mount_t *, xfs_sb_field_t, int, int);
+extern int xfs_mod_incore_sb_unlocked(xfs_mount_t *, xfs_sb_field_t,
+ int, int);
extern int xfs_mod_incore_sb_batch(xfs_mount_t *, xfs_mod_sb_t *,
uint, int);
extern struct xfs_buf *xfs_getsb(xfs_mount_t *, int);