PM / sleep: Measure the time of filesystems syncing

Measure the filesystems sync time during system sleep more precisely.

Among other things, this allows the pr_cont() to be dropped from
ksys_sync_helper() and makes automatic system suspend and hibernation
profiling somewhat more straightforward.

Signed-off-by: Harry Pan <harry.pan@intel.com>
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/kernel/power/main.c b/kernel/power/main.c
index 40472a7c5536..4f43e724f6eb 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -54,9 +54,14 @@ EXPORT_SYMBOL_GPL(unlock_system_sleep);
 
 void ksys_sync_helper(void)
 {
-        pr_info("Syncing filesystems ... ");
+        ktime_t start;
+        long elapsed_msecs;
+
+        start = ktime_get();
         ksys_sync();
-        pr_cont("done.\n");
+        elapsed_msecs = ktime_to_ms(ktime_sub(ktime_get(), start));
+        pr_info("Filesystems sync: %ld.%03ld seconds\n",
+                elapsed_msecs / MSEC_PER_SEC, elapsed_msecs % MSEC_PER_SEC);
 }
 EXPORT_SYMBOL_GPL(ksys_sync_helper);