[PATCH 7/9] spaceman/defrag: sleeps between segments

[Wengang Wang <wen.gang.wang@oracle.com>]

Let user contol the time to sleep between segments (file unlocked) to
balance defrag performance and file IO servicing time.

Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
---
 spaceman/defrag.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/spaceman/defrag.c b/spaceman/defrag.c
index b5c5b187..415fe9c2 100644
--- a/spaceman/defrag.c
+++ b/spaceman/defrag.c
@@ -311,6 +311,9 @@ void defrag_sigint_handler(int dummy)
  */
 static long	g_limit_free_bytes = 1024 * 1024 * 1024;
 
+/* sleep time in us between segments, overwritten by paramter */
+static int		g_idle_time = 250 * 1000;
+
 /*
  * check if the free space in the FS is less than the _limit_
  * return true if so, false otherwise
@@ -487,6 +490,7 @@ defrag_xfs_defrag(char *file_path) {
 	int	scratch_fd = -1, defrag_fd = -1;
 	char	tmp_file_path[PATH_MAX+1];
 	struct file_clone_range clone;
+	int	sleep_time_us = 0;
 	char	*defrag_dir;
 	struct fsxattr	fsx;
 	int	ret = 0;
@@ -574,6 +578,9 @@ defrag_xfs_defrag(char *file_path) {
 
 		/* checks for EoF and fix up clone */
 		stop = defrag_clone_eof(&clone);
+		if (sleep_time_us > 0)
+			usleep(sleep_time_us);
+
 		gettimeofday(&t_clone, NULL);
 		ret = ioctl(scratch_fd, FICLONERANGE, &clone);
 		if (ret != 0) {
@@ -587,6 +594,10 @@ defrag_xfs_defrag(char *file_path) {
 		if (time_delta > max_clone_us)
 			max_clone_us = time_delta;
 
+		/* sleeps if clone cost more than 500ms, slow FS */
+		if (time_delta >= 500000 && g_idle_time > 0)
+			usleep(g_idle_time);
+
 		/* for defrag stats */
 		nr_ext_defrag += segment.ds_nr;
 
@@ -641,6 +652,12 @@ defrag_xfs_defrag(char *file_path) {
 
 		if (stop || usedKilled)
 			break;
+
+		/*
+		 * no lock on target file when punching hole from scratch file,
+		 * so minus the time used for punching hole
+		 */
+		sleep_time_us = g_idle_time - time_delta;
 	} while (true);
 out:
 	if (scratch_fd != -1) {
@@ -678,6 +695,7 @@ static void defrag_help(void)
 " -f free_space      -- specify shrethod of the XFS free space in MiB, when\n"
 "                       XFS free space is lower than that, shared segments \n"
 "                       are excluded from defragmentation, 1024 by default\n"
+" -i idle_time       -- time in ms to be idle between segments, 250ms by default\n"
 " -n                 -- disable the \"share first extent\" featue, it's\n"
 "                       enabled by default to speed up\n"
 	));
@@ -691,7 +709,7 @@ defrag_f(int argc, char **argv)
 	int	i;
 	int	c;
 
-	while ((c = getopt(argc, argv, "s:f:n")) != EOF) {
+	while ((c = getopt(argc, argv, "s:f:ni")) != EOF) {
 		switch(c) {
 		case 's':
 			g_segment_size_lmt = atoi(optarg) * 1024 * 1024 / 512;
@@ -709,6 +727,10 @@ defrag_f(int argc, char **argv)
 			g_enable_first_ext_share = false;
 			break;
 
+		case 'i':
+			g_idle_time = atoi(optarg) * 1000;
+			break;
+
 		default:
 			command_usage(&defrag_cmd);
 			return 1;
@@ -726,7 +748,7 @@ void defrag_init(void)
 	defrag_cmd.cfunc	= defrag_f;
 	defrag_cmd.argmin	= 0;
 	defrag_cmd.argmax	= 4;
-	defrag_cmd.args		= "[-s segment_size] [-f free_space] [-n]";
+	defrag_cmd.args		= "[-s segment_size] [-f free_space] [-i idle_time] [-n]";
 	defrag_cmd.flags	= CMD_FLAG_ONESHOT;
 	defrag_cmd.oneline	= _("Defragment XFS files");
 	defrag_cmd.help		= defrag_help;
-- 
2.39.3 (Apple Git-146)