jbd2: track request delay statistics
Track the delay between when we first request that the commit begin
and when it actually begins, so we can see how much of a gap exists.
In theory, this should just be the remaining scheduling quantuum of
the thread which requested the commit (assuming it was not a
synchronous operation which triggered the commit request) plus
scheduling overhead; however, it's possible that real time processes
might get in the way of letting the kjournald thread from executing.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index e30b663..e0aafc4 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -581,6 +581,11 @@
unsigned long t_start;
/*
+ * When commit was requested
+ */
+ unsigned long t_requested;
+
+ /*
* Checkpointing stats [j_checkpoint_sem]
*/
struct transaction_chp_stats_s t_chp_stats;
@@ -637,6 +642,7 @@
struct transaction_run_stats_s {
unsigned long rs_wait;
+ unsigned long rs_request_delay;
unsigned long rs_running;
unsigned long rs_locked;
unsigned long rs_flushing;
@@ -649,6 +655,7 @@
struct transaction_stats_s {
unsigned long ts_tid;
+ unsigned long ts_requested;
struct transaction_run_stats_s run;
};