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-rw-r--r--include/linux/sched.h8
1 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index d2c881384517..28a98fc4ded4 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -350,11 +350,19 @@ struct load_weight {
* Only for tasks we track a moving average of the past instantaneous
* estimated utilization. This allows to absorb sporadic drops in utilization
* of an otherwise almost periodic task.
+ *
+ * The UTIL_AVG_UNCHANGED flag is used to synchronize util_est with util_avg
+ * updates. When a task is dequeued, its util_est should not be updated if its
+ * util_avg has not been updated in the meantime.
+ * This information is mapped into the MSB bit of util_est.enqueued at dequeue
+ * time. Since max value of util_est.enqueued for a task is 1024 (PELT util_avg
+ * for a task) it is safe to use MSB.
*/
struct util_est {
unsigned int enqueued;
unsigned int ewma;
#define UTIL_EST_WEIGHT_SHIFT 2
+#define UTIL_AVG_UNCHANGED 0x80000000
} __attribute__((__aligned__(sizeof(u64))));
/*