record ioctl elapsed time in zpool history

Each zfs ioctl that changes on-disk state (e.g. set property, create
snapshot, destroy filesystem) is recorded in the zpool history, and is
printed by `zpool history -i`.

For performance diagnostic purposes, it would be useful to know how long
each of these ioctls took to run.  This commit adds that functionality,
with a new `ZPOOL_HIST_ELAPSED_NS` member of the history nvlist.

Additionally, the time recorded in this history log is currently the
time that the history record is written to disk.  But in many cases (CLI
args logging and ioctl logging), this happens asynchronously,
potentially many seconds after the operation completed.  This commit
changes the timestamp to reflect when the history event was created,
rather than when it was written to disk.

Reviewed-by: Mark Maybee <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Matthew Ahrens <[email protected]>
Closes #11440 

1 files changed, 9 insertions, 1 deletions

diff --git a/cmd/zpool/zpool_main.c b/cmd/zpool/zpool_main.c
index e00fdb7ae..a13ff5ebd 100644
--- a/cmd/zpool/zpool_main.c
+++ b/cmd/zpool/zpool_main.c
@@ -9063,7 +9063,7 @@ print_history_records(nvlist_t *nvhis, hist_cbdata_t *cb)
 	    &records, &numrecords) == 0);
 	for (i = 0; i < numrecords; i++) {
 		nvlist_t *rec = records[i];
-		char tbuf[30] = "";
+		char tbuf[64] = "";
 
 		if (nvlist_exists(rec, ZPOOL_HIST_TIME)) {
 			time_t tsec;
@@ -9075,6 +9075,14 @@ print_history_records(nvlist_t *nvhis, hist_cbdata_t *cb)
 			(void) strftime(tbuf, sizeof (tbuf), "%F.%T", &t);
 		}
 
+		if (nvlist_exists(rec, ZPOOL_HIST_ELAPSED_NS)) {
+			uint64_t elapsed_ns = fnvlist_lookup_int64(records[i],
+			    ZPOOL_HIST_ELAPSED_NS);
+			(void) snprintf(tbuf + strlen(tbuf),
+			    sizeof (tbuf) - strlen(tbuf),
+			    " (%lldms)", (long long)elapsed_ns / 1000 / 1000);
+		}
+
 		if (nvlist_exists(rec, ZPOOL_HIST_CMD)) {
 			(void) printf("%s %s", tbuf,
 			    fnvlist_lookup_string(rec, ZPOOL_HIST_CMD));