lkml.org 
[lkml]   [2019]   [Dec]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH RFC] sched: Micro optimization in pick_next_task() and in check_preempt_curr()
From
Date
On 19.12.2019 17:43, Steven Rostedt wrote:
> On Thu, 19 Dec 2019 17:25:40 +0300
> Kirill Tkhai <ktkhai@virtuozzo.com> wrote:
>
>> (17:19:25) nbjoerg: but it is not guarenteed behavior
>> (17:19:50) nbjoerg: if for some strange reason you really need to enforce relative orders of global objects, put them in consecutively named sections
>
> Which appears to work. I tried this patch on top of yours:
>
> Not sure how this does with locality though.

Hm, I'm not sure, but AFAIR some (all?) sections are aligned at 4K.
Will this bring holes (4K-sizeof(struct sched_class)) in address
space?


> -- Steve
>
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index e00f41aa8ec4..ff12a422ff19 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -108,6 +108,13 @@
> #define SBSS_MAIN .sbss
> #endif
>
> +#define SCHED_DATA \
> + *(__idle_sched_class) \
> + *(__fair_sched_class) \
> + *(__rt_sched_class) \
> + *(__dl_sched_class) \
> + *(__stop_sched_class)
> +
> /*
> * Align to a 32 byte boundary equal to the
> * alignment gcc 4.5 uses for a struct
> @@ -308,6 +315,7 @@
> #define DATA_DATA \
> *(.xiptext) \
> *(DATA_MAIN) \
> + SCHED_DATA \
> *(.ref.data) \
> *(.data..shared_aligned) /* percpu related */ \
> MEM_KEEP(init.data*) \
> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
> index 43323f875cb9..5abdbe569f93 100644
> --- a/kernel/sched/deadline.c
> +++ b/kernel/sched/deadline.c
> @@ -2428,7 +2428,8 @@ static void prio_changed_dl(struct rq *rq, struct task_struct *p,
> }
> }
>
> -const struct sched_class dl_sched_class = {
> +const struct sched_class dl_sched_class
> + __attribute__((section("__dl_sched_class"))) = {
> .next = &rt_sched_class,
> .enqueue_task = enqueue_task_dl,
> .dequeue_task = dequeue_task_dl,
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 08a233e97a01..e745fe0e0cd3 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -10745,7 +10745,8 @@ static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task
> /*
> * All the scheduling class methods:
> */
> -const struct sched_class fair_sched_class = {
> +const struct sched_class fair_sched_class
> + __attribute__((section("__fair_sched_class"))) = {
> .next = &idle_sched_class,
> .enqueue_task = enqueue_task_fair,
> .dequeue_task = dequeue_task_fair,
> diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
> index ffa959e91227..700a9c826f0e 100644
> --- a/kernel/sched/idle.c
> +++ b/kernel/sched/idle.c
> @@ -454,7 +454,8 @@ static void update_curr_idle(struct rq *rq)
> /*
> * Simple, special scheduling class for the per-CPU idle tasks:
> */
> -const struct sched_class idle_sched_class = {
> +const struct sched_class idle_sched_class
> + __attribute__((section("__idle_sched_class"))) = {
> /* .next is NULL */
> /* no enqueue/yield_task for idle tasks */
>
> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
> index e591d40fd645..5d3f9bcddaeb 100644
> --- a/kernel/sched/rt.c
> +++ b/kernel/sched/rt.c
> @@ -2354,7 +2354,8 @@ static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
> return 0;
> }
>
> -const struct sched_class rt_sched_class = {
> +const struct sched_class rt_sched_class
> + __attribute__((section("__rt_sched_class"))) = {
> .next = &fair_sched_class,
> .enqueue_task = enqueue_task_rt,
> .dequeue_task = dequeue_task_rt,
> diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c
> index 4c9e9975684f..03bc7530ff75 100644
> --- a/kernel/sched/stop_task.c
> +++ b/kernel/sched/stop_task.c
> @@ -115,7 +115,8 @@ 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,
>

\
 
 \ /
  Last update: 2019-12-19 15:46    [W:0.135 / U:0.908 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site