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-rw-r--r--mm/backing-dev.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 65d420499a6..55627306abe 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -764,12 +764,17 @@ EXPORT_SYMBOL(set_bdi_congested);
long congestion_wait(int sync, long timeout)
{
long ret;
+ unsigned long start = jiffies;
DEFINE_WAIT(wait);
wait_queue_head_t *wqh = &congestion_wqh[sync];
prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
ret = io_schedule_timeout(timeout);
finish_wait(wqh, &wait);
+
+ trace_writeback_congestion_wait(jiffies_to_usecs(timeout),
+ jiffies_to_usecs(jiffies - start));
+
return ret;
}
EXPORT_SYMBOL(congestion_wait);