[ well, don't expect to find here anything like RDCFS
(no, 'D' does not stand for 'dumb'!). I was focused
on more prosaic things in the mean time so just
didn't have time for writing it.. ]
here is a few cleanup/simplification/optimization(s)
based on the recent modifications in the sched-dev tree.
(1) optimize task_new_fair()
(2) simplify yield_task()
(3) rework enqueue/dequeue_entity() to get rid of
sched_class::set_curr_task()
additionally, the changes somewhat decrease code size:
text data bss dec hex filename
43538 5398 48 48984 bf58 build/kernel/sched.o.before
43250 5390 48 48688 be30 build/kernel/sched.o
(SMP + lots of debugging options but, I guess, in this case the diff
should remain visible for any combination).
---
(1)
due to the fact that we no longer keep the 'current' within the tree,
dequeue/enqueue_entity() is useless for the 'current' in task_new_fair().
We are about to reschedule and sched_class->put_prev_task() will put
the 'current' back into the tree, based on its new key.
Signed-off-by: Dmitry Adamushko <[email protected]>
---
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 6e52d5a..5a244e2 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -969,10 +969,11 @@ static void task_new_fair(struct rq *rq, struct task_struct *p)
if (sysctl_sched_child_runs_first &&
curr->vruntime < se->vruntime) {
-
- dequeue_entity(cfs_rq, curr, 0);
+ /*
+ * Upon rescheduling, sched_class::put_prev_task() will place
+ * 'current' within the tree based on its new key value.
+ */
swap(curr->vruntime, se->vruntime);
- enqueue_entity(cfs_rq, curr, 0);
}
update_stats_enqueue(cfs_rq, se);
---
Dmitry
-
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