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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>
This commit is contained in:
Dave Chinner 2012-04-24 16:33:31 +10:00 committed by Ben Myers
parent 3ba3160374
commit 14c26c6a05
2 changed files with 18 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
fs/xfs/xfs_log.c
View File

@ -2941,6 +2941,7 @@ xfs_log_force(
{
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 @@ xfs_log_force_lsn(
{
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);

16
fs/xfs/xfs_trace.h
View File

@ -874,6 +874,22 @@ DECLARE_EVENT_CLASS(xfs_log_item_class,
__print_flags(__entry->flags, "|", XFS_LI_FLAGS))
)
TRACE_EVENT(xfs_log_force,
TP_PROTO(struct xfs_mount *mp, xfs_lsn_t lsn),
TP_ARGS(mp, lsn),
TP_STRUCT__entry(
__field(dev_t, dev)
__field(xfs_lsn_t, lsn)
),
TP_fast_assign(
__entry->dev = mp->m_super->s_dev;
__entry->lsn = lsn;
),
TP_printk("dev %d:%d lsn 0x%llx",
MAJOR(__entry->dev), MINOR(__entry->dev),
__entry->lsn)
)
#define DEFINE_LOG_ITEM_EVENT(name) \
DEFINE_EVENT(xfs_log_item_class, name, \
TP_PROTO(struct xfs_log_item *lip), \