xfs: add trace points for log forces
To enable easy tracing of the location of log forces and the
frequency of them via perf, add a pair of trace points to the log
force functions. This will help debug where excessive log forces
are being issued from by simple perf commands like:
# ~/perf/perf top -e xfs:xfs_log_force -G -U
Which gives this sort of output:
Events: 141 xfs:xfs_log_force
- 100.00% [kernel] [k] xfs_log_force
- xfs_log_force
87.04% xfsaild
kthread
kernel_thread_helper
- 12.87% xfs_buf_lock
_xfs_buf_find
xfs_buf_get
xfs_trans_get_buf
xfs_da_do_buf
xfs_da_get_buf
xfs_dir2_data_init
xfs_dir2_leaf_addname
xfs_dir_createname
xfs_create
xfs_vn_mknod
xfs_vn_create
vfs_create
do_last.isra.41
path_openat
do_filp_open
do_sys_open
sys_open
system_call_fastpath
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sig.com>
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 9b10a15..6b965bf 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -2941,6 +2941,7 @@
{
int error;
+ trace_xfs_log_force(mp, 0);
error = _xfs_log_force(mp, flags, NULL);
if (error)
xfs_warn(mp, "%s: error %d returned.", __func__, error);
@@ -3089,6 +3090,7 @@
{
int error;
+ trace_xfs_log_force(mp, lsn);
error = _xfs_log_force_lsn(mp, lsn, flags, NULL);
if (error)
xfs_warn(mp, "%s: error %d returned.", __func__, error);