Re: [PATCH V3] sched: fix autogroup nice tune on UP

[Mike Galbraith <efault@gmx.de>]

On Mon, 2011-01-24 at 15:33 +0800, Yong Zhang wrote:
> On Mon, Jan 24, 2011 at 08:18:11AM +0200, Pekka Enberg wrote:
> > I proposed extracting the shares calculation logic in
> > update_cfs_shares() to reduce code duplication for the SMP and UP
> > patch. So something like this:
> 
> Thanks for your example.
> So something like this?

I plugged this and your first into P4 box, and took it for a brief
test-drive... seems all better now.

	-Mike


> ---
> From: Yong Zhang <yong.zhang0@gmail.com>
> Subject: [PATCH V3] sched: fix autogroup nice tune on UP
> 
> When on UP with FAIR_GROUP_SCHED enabled, tune shares
> only affect tg->shares, but is not reflected on
> tg->se->load, the reason is update_cfs_shares()
> do nothing on UP.
> So introduce update_cfs_shares() for UP && FAIR_GROUP_SCHED.
> 
> This issue is found when enable autogroup, but also
> exists on cgroup.cpu on UP.
> 
> Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Mike Galbraith <efault@gmx.de>
> ---
> 
> Changelog from V2:
>   Move share caculation to calc_cfs_shares(), thus save
>   some duplicated code for update_cfs_shares().
>   Idea from Pekka Enberg.
> 
>  kernel/sched_fair.c |   78 ++++++++++++++++++++++++++++++++++----------------
>  1 files changed, 53 insertions(+), 25 deletions(-)
> 
> diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
> index 77e9166..3547699 100644
> --- a/kernel/sched_fair.c
> +++ b/kernel/sched_fair.c
> @@ -699,7 +699,8 @@ account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
>  	cfs_rq->nr_running--;
>  }
>  
> -#if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
> +#ifdef CONFIG_FAIR_GROUP_SCHED
> +# ifdef CONFIG_SMP
>  static void update_cfs_rq_load_contribution(struct cfs_rq *cfs_rq,
>  					    int global_update)
>  {
> @@ -762,6 +763,51 @@ static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
>  		list_del_leaf_cfs_rq(cfs_rq);
>  }
>  
> +static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg,
> +				long weight_delta)
> +{
> +	long load_weight, load, shares;
> +
> +	load = cfs_rq->load.weight + weight_delta;
> +
> +	load_weight = atomic_read(&tg->load_weight);
> +	load_weight -= cfs_rq->load_contribution;
> +	load_weight += load;
> +
> +	shares = (tg->shares * load);
> +	if (load_weight)
> +		shares /= load_weight;
> +
> +	if (shares < MIN_SHARES)
> +		shares = MIN_SHARES;
> +	if (shares > tg->shares)
> +		shares = tg->shares;
> +
> +	return shares;
> +}
> +
> +static void update_entity_shares_tick(struct cfs_rq *cfs_rq)
> +{
> +	if (cfs_rq->load_unacc_exec_time > sysctl_sched_shares_window) {
> +		update_cfs_load(cfs_rq, 0);
> +		update_cfs_shares(cfs_rq, 0);
> +	}
> +}
> +# else /* CONFIG_SMP */
> +static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
> +{
> +}
> +
> +static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg,
> +				long weight_delta)
> +{
> +	return tg->shares;
> +}
> +
> +static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq)
> +{
> +}
> +# endif /* CONFIG_SMP */
>  static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
>  			    unsigned long weight)
>  {
> @@ -782,7 +828,7 @@ static void update_cfs_shares(struct cfs_rq *cfs_rq, long weight_delta)
>  {
>  	struct task_group *tg;
>  	struct sched_entity *se;
> -	long load_weight, load, shares;
> +	long shares;
>  
>  	if (!cfs_rq)
>  		return;
> @@ -791,32 +837,14 @@ static void update_cfs_shares(struct cfs_rq *cfs_rq, long weight_delta)
>  	se = tg->se[cpu_of(rq_of(cfs_rq))];
>  	if (!se)
>  		return;
> -
> -	load = cfs_rq->load.weight + weight_delta;
> -
> -	load_weight = atomic_read(&tg->load_weight);
> -	load_weight -= cfs_rq->load_contribution;
> -	load_weight += load;
> -
> -	shares = (tg->shares * load);
> -	if (load_weight)
> -		shares /= load_weight;
> -
> -	if (shares < MIN_SHARES)
> -		shares = MIN_SHARES;
> -	if (shares > tg->shares)
> -		shares = tg->shares;
> +#ifndef CONFIG_SMP
> +	if (likely(se->load.weight == tg->shares))
> +		return;
> +#endif
> +	shares = calc_cfs_shares(cfs_rq, tg, weight_delta);
>  
>  	reweight_entity(cfs_rq_of(se), se, shares);
>  }
> -
> -static void update_entity_shares_tick(struct cfs_rq *cfs_rq)
> -{
> -	if (cfs_rq->load_unacc_exec_time > sysctl_sched_shares_window) {
> -		update_cfs_load(cfs_rq, 0);
> -		update_cfs_shares(cfs_rq, 0);
> -	}
> -}
>  #else /* CONFIG_FAIR_GROUP_SCHED */
>  static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
>  {