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| author | Peter Zijlstra <peterz@infradead.org> | 2019-05-29 20:36:44 +0000 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2019-08-08 09:09:31 +0200 |
| commit | 67692435c411e5c53a1c588ecca2037aebd81f2e (patch) | |
| tree | 53d9c44e6e80654a60c652493d4b0cc948ce5818 /kernel/sched/fair.c | |
| parent | 5f2a45fc9e89e022233085e6f0f352eb6ff770bb (diff) | |
sched: Rework pick_next_task() slow-path
Avoid the RETRY_TASK case in the pick_next_task() slow path.
By doing the put_prev_task() early, we get the rt/deadline pull done,
and by testing rq->nr_running we know if we need newidle_balance().
This then gives a stable state to pick a task from.
Since the fast-path is fair only; it means the other classes will
always have pick_next_task(.prev=NULL, .rf=NULL) and we can simplify.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Lu <aaron.lwe@gmail.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: mingo@kernel.org
Cc: Phil Auld <pauld@redhat.com>
Cc: Julien Desfossez <jdesfossez@digitalocean.com>
Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>
Link: https://lkml.kernel.org/r/aa34d24b36547139248f32a30138791ac6c02bd6.1559129225.git.vpillai@digitalocean.com
Diffstat (limited to 'kernel/sched/fair.c')
| -rw-r--r-- | kernel/sched/fair.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 4418c1998e69..19c58599e967 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6770,7 +6770,7 @@ again: goto idle; #ifdef CONFIG_FAIR_GROUP_SCHED - if (prev->sched_class != &fair_sched_class) + if (!prev || prev->sched_class != &fair_sched_class) goto simple; /* @@ -6847,8 +6847,8 @@ again: goto done; simple: #endif - - put_prev_task(rq, prev); + if (prev) + put_prev_task(rq, prev); do { se = pick_next_entity(cfs_rq, NULL); @@ -6876,6 +6876,9 @@ done: __maybe_unused; return p; idle: + if (!rf) + return NULL; + new_tasks = newidle_balance(rq, rf); /* |