[CRIU] [PATCH] seize: Take --timeout option into account when freezing processes

[Cyrill Gorcunov]

When we're freezing processes we don't count on anything but
rather do 5 attempts with constantly increasing delay.

Lets rather do the following:

 - take --timeout option into account (which is 5 seconds
   by default) and split it into 100 ms steps;

 - when frezing processes check freezer status every 100 ms.

Same time it looks that 5 seconds by default is too small
for high loaded containers. Lets increase it to 10 seconds
by default.

Reported-by: Stanislav Kinsburskiy <skinsbursky at virtuozzo.com>
Signed-off-by: Cyrill Gorcunov <gorcunov at virtuozzo.com>
---
 criu/include/cr_options.h |  2 +-
 criu/seize.c              | 30 ++++++++++++++++++++----------
 2 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/criu/include/cr_options.h b/criu/include/cr_options.h
index b6ae3a1..a9ca1f8 100644
--- a/criu/include/cr_options.h
+++ b/criu/include/cr_options.h
@@ -38,7 +38,7 @@ struct cg_root_opt {
  */
 #define DEFAULT_GHOST_LIMIT	(1 << 20)
 
-#define DEFAULT_TIMEOUT		5
+#define DEFAULT_TIMEOUT		10
 
 struct irmap;
 
diff --git a/criu/seize.c b/criu/seize.c
index 0ea7a28..863a21e 100644
--- a/criu/seize.c
+++ b/criu/seize.c
@@ -244,10 +244,27 @@ static int freezer_detach(void)
 
 static int freeze_processes(void)
 {
-	int i, fd, exit_code = -1;
+	int fd, exit_code = -1;
 	char path[PATH_MAX];
 	const char *state = thawed;
 
+	static const unsigned long step_ms = 100;
+	unsigned long nr_attempts = (opts.timeout * 1000000) / step_ms;
+	unsigned long i;
+
+	const struct timespec req = {
+		.tv_nsec	= step_ms * 1000000,
+		.tv_sec		= 0,
+	};
+
+	if (unlikely(!nr_attempts)) {
+		/*
+		 * If timeout is turned off, lets
+		 * wait for at least 10 seconds.
+		 */
+		nr_attempts = (10 * 1000000) / step_ms;
+	}
+
 	snprintf(path, sizeof(path), "%s/freezer.state", opts.freeze_cgroup);
 	fd = open(path, O_RDWR);
 	if (fd < 0) {
@@ -275,10 +292,7 @@ static int freeze_processes(void)
 	 * freezer.state.
 	 * Here is one extra attempt to check that everything are frozen.
 	 */
-	for (i = 0; i <= NR_ATTEMPTS; i++) {
-		struct timespec req = {};
-		u64 timeout;
-
+	for (i = 0; i <= nr_attempts; i++) {
 		if (seize_cgroup_tree(opts.freeze_cgroup, state) < 0)
 			goto err;
 
@@ -300,14 +314,10 @@ static int freeze_processes(void)
 
 		if (alarm_timeouted())
 			goto err;
-
-		timeout = 100000000 * (i + 1); /* 100 msec */
-		req.tv_nsec = timeout % 1000000000;
-		req.tv_sec = timeout / 1000000000;
 		nanosleep(&req, NULL);
 	}
 
-	if (i > NR_ATTEMPTS) {
+	if (i > nr_attempts) {
 		pr_err("Unable to freeze cgroup %s\n", opts.freeze_cgroup);
 		goto err;
 	}
-- 
2.5.5