On Mon, 10 Dec 2012 16:22:22 +0800, Alex Shi wrote:
> New task has no runnable sum at its first runnable time, that make
> burst forking just select few idle cpus to put tasks.
> Set initial load avg of new forked task as its load weight to resolve
> this issue.
>
> Signed-off-by: Alex Shi <[email protected]>
> ---
> include/linux/sched.h | 1 +
> kernel/sched/core.c | 2 +-
> kernel/sched/fair.c | 13 +++++++++++--
> 3 files changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 5dafac3..093f9cd 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -1058,6 +1058,7 @@ struct sched_domain;
> #else
> #define ENQUEUE_WAKING 0
> #endif
> +#define ENQUEUE_NEWTASK 8
>
> #define DEQUEUE_SLEEP 1
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index e6533e1..96fa5f1 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -1648,7 +1648,7 @@ void wake_up_new_task(struct task_struct *p)
> #endif
>
> rq = __task_rq_lock(p);
> - activate_task(rq, p, 0);
> + activate_task(rq, p, ENQUEUE_NEWTASK);
> p->on_rq = 1;
> trace_sched_wakeup_new(p, true);
> check_preempt_curr(rq, p, WF_FORK);
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 1faf89f..61c8d24 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -1277,8 +1277,9 @@ static inline void update_rq_runnable_avg(struct rq
> *rq, int runnable)
> /* Add the load generated by se into cfs_rq's child load-average */
> static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
> struct sched_entity *se,
> - int wakeup)
> + int flags)
> {
> + int wakeup = flags & ENQUEUE_WAKEUP;
> /*
> * We track migrations using entity decay_count <= 0, on a wake-up
> * migration we use a negative decay count to track the remote decays
> @@ -1312,6 +1313,12 @@ static inline void enqueue_entity_load_avg(struct
> cfs_rq *cfs_rq,
> update_entity_load_avg(se, 0);
> }
>
> + /*
> + * set the initial load avg of new task same as its load
> + * in order to avoid brust fork make few cpu too heavier
> + */
> + if (flags & ENQUEUE_NEWTASK)
> + se->avg.load_avg_contrib = se->load.weight;
> cfs_rq->runnable_load_avg += se->avg.load_avg_contrib;
> /* we force update consideration on load-balancer moves */
> update_cfs_rq_blocked_load(cfs_rq, !wakeup);
> @@ -1476,7 +1483,8 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct
> sched_entity *se, int flags)
> */
> update_curr(cfs_rq);
> account_entity_enqueue(cfs_rq, se);
> - enqueue_entity_load_avg(cfs_rq, se, flags & ENQUEUE_WAKEUP);
> + enqueue_entity_load_avg(cfs_rq, se, flags &
> + (ENQUEUE_WAKEUP | ENQUEUE_NEWTASK));
It seems that just passing 'flags' is enough.
>
> if (flags & ENQUEUE_WAKEUP) {
> place_entity(cfs_rq, se, 0);
> @@ -2586,6 +2594,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p,
> int flags)
> cfs_rq->h_nr_running++;
>
> flags = ENQUEUE_WAKEUP;
> + flags &= ~ENQUEUE_NEWTASK;
Why is this needed?
Thanks,
Namhyung
> }
>
> for_each_sched_entity(se) {
--
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