sched: Introduce task block time in schedstats

Currently in schedstats we have sum_sleep_runtime and iowait_sum, but
there's no metric to show how long the task is in D state.  Once a task in
D state, it means the task is blocked in the kernel, for example the
task may be waiting for a mutex. The D state is more frequent than
iowait, and it is more critital than S state. So it is worth to add a
metric to measure it.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210905143547.4668-5-laoar.shao@gmail.com

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 2bc4c72fec2d..193e16e2d0e4 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -503,6 +503,8 @@ struct sched_statistics {
 
 	u64				block_start;
 	u64				block_max;
+	s64				sum_block_runtime;
+
 	u64				exec_max;
 	u64				slice_max;