linux-kernel - Re: [Resend patch v8 06/13] sched: compute runnable load avg in cpu_load and cpu_avg_load_per

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Message-ID: <CAKfTPtACq+whBLEHUm2Vrf7rStKUViGaSX_fn=Kf4SduXOjvbg@mail.gmail.com>
Date:	Thu, 20 Jun 2013 15:29:23 +0200
From:	Vincent Guittot <vincent.guittot@...aro.org>
To:	Alex Shi <alex.shi@...el.com>
Cc:	"mingo@...hat.com" <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Borislav Petkov <bp@...en8.de>, Paul Turner <pjt@...gle.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Mike Galbraith <efault@....de>,
	Morten Rasmussen <morten.rasmussen@....com>,
	gregkh@...uxfoundation.org,
	Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Len Brown <len.brown@...el.com>, rafael.j.wysocki@...el.com,
	jkosina@...e.cz, Clark Williams <clark.williams@...il.com>,
	"tony.luck@...el.com" <tony.luck@...el.com>, keescook@...omium.org,
	Mel Gorman <mgorman@...e.de>, riel@...hat.com
Subject: Re: [Resend patch v8 06/13] sched: compute runnable load avg in
 cpu_load and cpu_avg_load_per_task

On 20 June 2013 04:18, Alex Shi <alex.shi@...el.com> wrote:
> They are the base values in load balance, update them with rq runnable
> load average, then the load balance will consider runnable load avg
> naturally.
>
> We also try to include the blocked_load_avg as cpu load in balancing,
> but that cause kbuild performance drop 6% on every Intel machine, and
> aim7/oltp drop on some of 4 CPU sockets machines.
> Or only add blocked_load_avg into get_rq_runable_load, hackbench still
> drop a little on NHM EX.
>
> Signed-off-by: Alex Shi <alex.shi@...el.com>
> Reviewed-by: Gu Zheng <guz.fnst@...fujitsu.com>
> ---
>  kernel/sched/fair.c |  5 +++--
>  kernel/sched/proc.c | 17 +++++++++++++++--
>  2 files changed, 18 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 1e5a5e6..7d5c477 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -2968,7 +2968,7 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
>  /* Used instead of source_load when we know the type == 0 */
>  static unsigned long weighted_cpuload(const int cpu)
>  {
> -       return cpu_rq(cpu)->load.weight;
> +       return cpu_rq(cpu)->cfs.runnable_load_avg;
>  }

Alex,

In the wake-affine function, we use current->se.load.weight  and
p->se.load.weight to update the load of this_cpu and prev_cpu whereas
these loads are now equal to runnable_load_avg which is the sum of
se->avg.load_avg_contrib now. Shouldn't we use
se->avg.load_avg_contrib instead of se.load.weight ?

Vincent

>
>  /*
> @@ -3013,9 +3013,10 @@ static unsigned long cpu_avg_load_per_task(int cpu)
>  {
>         struct rq *rq = cpu_rq(cpu);
>         unsigned long nr_running = ACCESS_ONCE(rq->nr_running);
> +       unsigned long load_avg = rq->cfs.runnable_load_avg;
>
>         if (nr_running)
> -               return rq->load.weight / nr_running;
> +               return load_avg / nr_running;
>
>         return 0;
>  }
> diff --git a/kernel/sched/proc.c b/kernel/sched/proc.c
> index bb3a6a0..ce5cd48 100644
> --- a/kernel/sched/proc.c
> +++ b/kernel/sched/proc.c
> @@ -501,6 +501,18 @@ static void __update_cpu_load(struct rq *this_rq, unsigned long this_load,
>         sched_avg_update(this_rq);
>  }
>
> +#ifdef CONFIG_SMP
> +unsigned long get_rq_runnable_load(struct rq *rq)
> +{
> +       return rq->cfs.runnable_load_avg;
> +}
> +#else
> +unsigned long get_rq_runnable_load(struct rq *rq)
> +{
> +       return rq->load.weight;
> +}
> +#endif
> +
>  #ifdef CONFIG_NO_HZ_COMMON
>  /*
>   * There is no sane way to deal with nohz on smp when using jiffies because the
> @@ -522,7 +534,7 @@ static void __update_cpu_load(struct rq *this_rq, unsigned long this_load,
>  void update_idle_cpu_load(struct rq *this_rq)
>  {
>         unsigned long curr_jiffies = ACCESS_ONCE(jiffies);
> -       unsigned long load = this_rq->load.weight;
> +       unsigned long load = get_rq_runnable_load(this_rq);
>         unsigned long pending_updates;
>
>         /*
> @@ -568,11 +580,12 @@ void update_cpu_load_nohz(void)
>   */
>  void update_cpu_load_active(struct rq *this_rq)
>  {
> +       unsigned long load = get_rq_runnable_load(this_rq);
>         /*
>          * See the mess around update_idle_cpu_load() / update_cpu_load_nohz().
>          */
>         this_rq->last_load_update_tick = jiffies;
> -       __update_cpu_load(this_rq, this_rq->load.weight, 1);
> +       __update_cpu_load(this_rq, load, 1);
>
>         calc_load_account_active(this_rq);
>  }
> --
> 1.7.12
>
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