freezer: measure freezing time

Measure the time of the freezing of tasks, even if it doesn't fail.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 3 deletions

diff --git a/kernel/power/process.c b/kernel/power/process.c
index 3d98d7f99b14..6533923e711b 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -168,6 +168,11 @@ static int try_to_freeze_tasks(int freeze_user_space)
         struct task_struct *g, *p;
         unsigned long end_time;
         unsigned int todo;
+        struct timeval start, end;
+        s64 elapsed_csecs64;
+        unsigned int elapsed_csecs;
+
+        do_gettimeofday(&start);
 
         end_time = jiffies + TIMEOUT;
         do {
@@ -194,6 +199,11 @@ static int try_to_freeze_tasks(int freeze_user_space)
                         break;
         } while (todo);
 
+        do_gettimeofday(&end);
+        elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
+        do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
+        elapsed_csecs = elapsed_csecs64;
+
         if (todo) {
                 /* This does not unfreeze processes that are already frozen
                  * (we have slightly ugly calling convention in that respect,
@@ -201,10 +211,9 @@ static int try_to_freeze_tasks(int freeze_user_space)
                  * but it cleans up leftover PF_FREEZE requests.
                  */
                 printk("\n");
-                printk(KERN_ERR "Freezing of %s timed out after %d seconds "
+                printk(KERN_ERR "Freezing of tasks failed after %d.%02d seconds "
                                 "(%d tasks refusing to freeze):\n",
-                                freeze_user_space ? "user space " : "tasks ",
-                                TIMEOUT / HZ, todo);
+                                elapsed_csecs / 100, elapsed_csecs % 100, todo);
                 show_state();
                 read_lock(&tasklist_lock);
                 do_each_thread(g, p) {
@@ -215,6 +224,9 @@ static int try_to_freeze_tasks(int freeze_user_space)
                         task_unlock(p);
                 } while_each_thread(g, p);
                 read_unlock(&tasklist_lock);
+        } else {
+                printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
+                        elapsed_csecs % 100);
         }
 
         return todo ? -EBUSY : 0;