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| author |   Kirill Tkhai <tkhai@yandex.ru> | 2019-12-19 16:44:55 -0500 |
|---|---|---|
| committer |   Peter Zijlstra <peterz@infradead.org> | 2020-06-25 13:45:44 +0200 |
| commit | aa93cd53bc1b91b5f99c7b55e3dcc1ac98e99558 (patch) | |
| tree | 3cde032f84a6a2d529c92aa7e081dec7db2dd5dd /kernel/sched | |
| parent | sched: Remove struct sched_class::next field (diff) | |
| download | wireguard-linux-aa93cd53bc1b91b5f99c7b55e3dcc1ac98e99558.tar.xz wireguard-linux-aa93cd53bc1b91b5f99c7b55e3dcc1ac98e99558.zip | |
sched: Micro optimization in pick_next_task() and in check_preempt_curr()
This introduces an optimization based on xxx_sched_class addresses
in two hot scheduler functions: pick_next_task() and check_preempt_curr().
It is possible to compare pointers to sched classes to check, which
of them has a higher priority, instead of current iterations using
for_each_class().
One more result of the patch is that size of object file becomes a little
less (excluding added BUG_ON(), which goes in __init section):
$size kernel/sched/core.o
text data bss dec hex filename
before: 66446 18957 676 86079 1503f kernel/sched/core.o
after: 66398 18957 676 86031 1500f kernel/sched/core.o
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/711a9c4b-ff32-1136-b848-17c622d548f3@yandex.ru
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/core.c | 19 |
1 files changed, 4 insertions, 15 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 81640fe0eae8..0a08d0c235d4 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1412,20 +1412,10 @@ static inline void check_class_changed(struct rq *rq, struct task_struct *p, void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags) { - const struct sched_class *class; - - if (p->sched_class == rq->curr->sched_class) { + if (p->sched_class == rq->curr->sched_class) rq->curr->sched_class->check_preempt_curr(rq, p, flags); - } else { - for_each_class(class) { - if (class == rq->curr->sched_class) - break; - if (class == p->sched_class) { - resched_curr(rq); - break; - } - } - } + else if (p->sched_class > rq->curr->sched_class) + resched_curr(rq); /* * A queue event has occurred, and we're going to schedule. In @@ -4003,8 +3993,7 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) * higher scheduling class, because otherwise those loose the * opportunity to pull in more work from other CPUs. */ - if (likely((prev->sched_class == &idle_sched_class || - prev->sched_class == &fair_sched_class) && + if (likely(prev->sched_class <= &fair_sched_class && rq->nr_running == rq->cfs.h_nr_running)) { p = pick_next_task_fair(rq, prev, rf); |