From e3e76a6a04114ec95b0969cd026e8904c67b431b Mon Sep 17 00:00:00 2001 From: Dietmar Eggemann Date: Wed, 3 Jun 2020 10:03:03 +0200 Subject: sched/idle,stop: Remove .get_rr_interval from sched_class The idle task and stop task sched_classes return 0 in this function. The single call site in sched_rr_get_interval() calls p->sched_class->get_rr_interval() only conditional in case it is defined. Otherwise time_slice=0 will be used. The deadline sched class does not define it. Commit a57beec5d427 ("sched: Make sched_class::get_rr_interval() optional") introduced the default time-slice=0 for sched classes which do not provide this function. So .get_rr_interval for idle and stop sched_class can be removed to shrink the code a little. Signed-off-by: Dietmar Eggemann Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200603080304.16548-4-dietmar.eggemann@arm.com --- kernel/sched/stop_task.c | 8 -------- 1 file changed, 8 deletions(-) (limited to 'kernel/sched/stop_task.c') diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c index 4c9e9975684f..3e50a6a8f1e5 100644 --- a/kernel/sched/stop_task.c +++ b/kernel/sched/stop_task.c @@ -102,12 +102,6 @@ prio_changed_stop(struct rq *rq, struct task_struct *p, int oldprio) BUG(); /* how!?, what priority? */ } -static unsigned int -get_rr_interval_stop(struct rq *rq, struct task_struct *task) -{ - return 0; -} - static void update_curr_stop(struct rq *rq) { } @@ -136,8 +130,6 @@ const struct sched_class stop_sched_class = { .task_tick = task_tick_stop, - .get_rr_interval = get_rr_interval_stop, - .prio_changed = prio_changed_stop, .switched_to = switched_to_stop, .update_curr = update_curr_stop, -- cgit v1.2.3 From 590d69796346353878b275c5512c664e3f875f24 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Thu, 19 Dec 2019 16:44:52 -0500 Subject: sched: Force the address order of each sched class descriptor In order to make a micro optimization in pick_next_task(), the order of the sched class descriptor address must be in the same order as their priority to each other. That is: &idle_sched_class < &fair_sched_class < &rt_sched_class < &dl_sched_class < &stop_sched_class In order to guarantee this order of the sched class descriptors, add each one into their own data section and force the order in the linker script. Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/157675913272.349305.8936736338884044103.stgit@localhost.localdomain --- kernel/sched/stop_task.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel/sched/stop_task.c') diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c index 3e50a6a8f1e5..f4bbd54caae0 100644 --- a/kernel/sched/stop_task.c +++ b/kernel/sched/stop_task.c @@ -109,7 +109,8 @@ static void update_curr_stop(struct rq *rq) /* * Simple, special scheduling class for the per-CPU stop tasks: */ -const struct sched_class stop_sched_class = { +const struct sched_class stop_sched_class + __attribute__((section("__stop_sched_class"))) = { .next = &dl_sched_class, .enqueue_task = enqueue_task_stop, -- cgit v1.2.3 From a87e749e8fa1aaef9b4db32e21c2795e69ce67bf Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Thu, 19 Dec 2019 16:44:54 -0500 Subject: sched: Remove struct sched_class::next field Now that the sched_class descriptors are defined in order via the linker script vmlinux.lds.h, there's no reason to have a "next" pointer to the previous priroity structure. The order of the sturctures can be aligned as an array, and used to index and find the next sched_class descriptor. Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20191219214558.845353593@goodmis.org --- kernel/sched/stop_task.c | 1 - 1 file changed, 1 deletion(-) (limited to 'kernel/sched/stop_task.c') diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c index f4bbd54caae0..394bc8126a1e 100644 --- a/kernel/sched/stop_task.c +++ b/kernel/sched/stop_task.c @@ -111,7 +111,6 @@ static void update_curr_stop(struct rq *rq) */ const struct sched_class stop_sched_class __attribute__((section("__stop_sched_class"))) = { - .next = &dl_sched_class, .enqueue_task = enqueue_task_stop, .dequeue_task = dequeue_task_stop, -- cgit v1.2.3