Add -y option to `zpool iostat`

sysstat's iostat omits the first report when the -y option is used.
This patch adds that functionality and omits the first report with
statistics since system boot.

Signed-off-by: Hajo Möller <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #3439

1 files changed, 23 insertions, 8 deletions

diff --git a/cmd/zpool/zpool_main.c b/cmd/zpool/zpool_main.c
index 5c28e8bb1..fd1e8284a 100644
--- a/cmd/zpool/zpool_main.c
+++ b/cmd/zpool/zpool_main.c
@@ -236,8 +236,8 @@ get_usage(zpool_help_t idx) {
 		    "[-R root] [-F [-n]]\n"
 		    "\t    <pool | id> [newpool]\n"));
 	case HELP_IOSTAT:
-		return (gettext("\tiostat [-v] [-T d|u] [pool] ... [interval "
-		    "[count]]\n"));
+		return (gettext("\tiostat [-v] [-T d|u] [-y] [pool] ... "
+		    "[interval [count]]\n"));
 	case HELP_LABELCLEAR:
 		return (gettext("\tlabelclear [-f] <vdev>\n"));
 	case HELP_LIST:
@@ -2817,10 +2817,11 @@ zpool_do_iostat(int argc, char **argv)
 	unsigned long interval = 0, count = 0;
 	zpool_list_t *list;
 	boolean_t verbose = B_FALSE;
+	boolean_t omit_since_boot = B_FALSE;
 	iostat_cbdata_t cb;
 
 	/* check options */
-	while ((c = getopt(argc, argv, "T:v")) != -1) {
+	while ((c = getopt(argc, argv, "T:vy")) != -1) {
 		switch (c) {
 		case 'T':
 			get_timestamp_arg(*optarg);
@@ -2828,6 +2829,9 @@ zpool_do_iostat(int argc, char **argv)
 		case 'v':
 			verbose = B_TRUE;
 			break;
+		case 'y':
+			omit_since_boot = B_TRUE;
+			break;
 		case '?':
 			(void) fprintf(stderr, gettext("invalid option '%c'\n"),
 			    optopt);
@@ -2867,12 +2871,17 @@ zpool_do_iostat(int argc, char **argv)
 	cb.cb_namewidth = 0;
 
 	for (;;) {
-		pool_list_update(list);
-
 		if ((npools = pool_list_count(list)) == 0)
 			(void) fprintf(stderr, gettext("no pools available\n"));
 		else {
 			/*
+			 * If this is the first iteration and -y was supplied
+			 * we skip any printing.
+			 */
+			boolean_t skip = (omit_since_boot &&
+				cb.cb_iteration == 0);
+
+			/*
 			 * Refresh all statistics.  This is done as an
 			 * explicit step before calculating the maximum name
 			 * width, so that any * configuration changes are
@@ -2893,12 +2902,18 @@ zpool_do_iostat(int argc, char **argv)
 				print_timestamp(timestamp_fmt);
 
 			/*
-			 * If it's the first time, or verbose mode, print the
-			 * header.
+			 * If it's the first time and we're not skipping it,
+			 * or either skip or verbose mode, print the header.
 			 */
-			if (++cb.cb_iteration == 1 || verbose)
+			if ((++cb.cb_iteration == 1 && !skip) ||
+				(skip != verbose))
 				print_iostat_header(&cb);
 
+			if (skip) {
+				(void) sleep(interval);
+				continue;
+			}
+
 			(void) pool_list_iter(list, B_FALSE, print_iostat, &cb);
 
 			/*