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Date: Mon, 24 Jan 2011 10:00:28 +0100
From: Mike Galbraith <efault@....de>
To: Yong Zhang <yong.zhang0@...il.com>
Cc: Pekka Enberg <penberg@...nel.org>, linux-kernel@...r.kernel.org,
mfwitten@...il.com, christian@...dbynature.de,
a.p.zijlstra@...llo.nl, Ingo Molnar <mingo@...e.hu>,
Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH V3] sched: fix autogroup nice tune on UP
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@...il.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@...il.com>
> Cc: Ingo Molnar <mingo@...e.hu>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Mike Galbraith <efault@....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)
> {
--
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