From: Preeti U Murthy <preeti@linux.vnet.ibm.com>
To: Alex Shi <alex.shi@intel.com>
Cc: mingo@redhat.com, peterz@infradead.org, tglx@linutronix.de,
akpm@linux-foundation.org, arjan@linux.intel.com, bp@alien8.de,
pjt@google.com, namhyung@kernel.org, efault@gmx.de,
morten.rasmussen@arm.com, vincent.guittot@linaro.org,
gregkh@linuxfoundation.org, viresh.kumar@linaro.org,
linux-kernel@vger.kernel.org, len.brown@intel.com,
rafael.j.wysocki@intel.com, jkosina@suse.cz,
clark.williams@gmail.com, tony.luck@intel.com,
keescook@chromium.org, mgorman@suse.de, riel@redhat.com
Subject: Re: [patch v7 02/21] sched: set initial value of runnable avg for new forked task
Date: Mon, 06 May 2013 08:54:28 +0530 [thread overview]
Message-ID: <5187226C.3000509@linux.vnet.ibm.com> (raw)
In-Reply-To: <1365040862-8390-3-git-send-email-alex.shi@intel.com>
Hi Alex,
The below patch looks good to me.
On 04/04/2013 07:30 AM, Alex Shi wrote:
> We need initialize the se.avg.{decay_count, load_avg_contrib} for a
> new forked task.
> Otherwise random values of above variables cause mess when do new task
> enqueue:
> enqueue_task_fair
> enqueue_entity
> enqueue_entity_load_avg
>
> and make forking balancing imbalance since incorrect load_avg_contrib.
>
> set avg.decay_count = 0, and avg.load_avg_contrib = se->load.weight to
> resolve such issues.
>
> Signed-off-by: Alex Shi <alex.shi@intel.com>
> ---
> kernel/sched/core.c | 6 ++++++
> kernel/sched/fair.c | 4 ++++
> 2 files changed, 10 insertions(+)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 54eaaa2..8843cd3 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -1564,6 +1564,7 @@ static void __sched_fork(struct task_struct *p)
> #ifdef CONFIG_SMP
> p->se.avg.runnable_avg_period = 0;
> p->se.avg.runnable_avg_sum = 0;
> + p->se.avg.decay_count = 0;
> #endif
> #ifdef CONFIG_SCHEDSTATS
> memset(&p->se.statistics, 0, sizeof(p->se.statistics));
> @@ -1651,6 +1652,11 @@ void sched_fork(struct task_struct *p)
> p->sched_reset_on_fork = 0;
> }
>
> + /* New forked task assumed with full utilization */
> +#if defined(CONFIG_SMP)
> + p->se.avg.load_avg_contrib = p->se.load.weight;
> +#endif
> +
> if (!rt_prio(p->prio))
> p->sched_class = &fair_sched_class;
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 9c2f726..2881d42 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -1508,6 +1508,10 @@ static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
> * We track migrations using entity decay_count <= 0, on a wake-up
> * migration we use a negative decay count to track the remote decays
> * accumulated while sleeping.
> + *
> + * When enqueue a new forked task, the se->avg.decay_count == 0, so
> + * we bypass update_entity_load_avg(), use avg.load_avg_contrib initial
> + * value: se->load.weight.
> */
> if (unlikely(se->avg.decay_count <= 0)) {
> se->avg.last_runnable_update = rq_of(cfs_rq)->clock_task;
>
Reviewed-by:Preeti U Murthy
Thanks
Regards
Preeti U Murthy
next prev parent reply other threads:[~2013-05-06 3:26 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-04 2:00 [patch v7 0/21] sched: power aware scheduling Alex Shi
2013-04-04 2:00 ` [patch v7 01/21] Revert "sched: Introduce temporary FAIR_GROUP_SCHED dependency for load-tracking" Alex Shi
2013-04-04 2:00 ` [patch v7 02/21] sched: set initial value of runnable avg for new forked task Alex Shi
2013-05-06 3:24 ` Preeti U Murthy [this message]
2013-04-04 2:00 ` [patch v7 03/21] sched: add sched balance policies in kernel Alex Shi
2013-04-04 2:00 ` [patch v7 04/21] sched: add sysfs interface for sched_balance_policy selection Alex Shi
2013-04-04 2:00 ` [patch v7 05/21] sched: log the cpu utilization at rq Alex Shi
2013-05-06 3:26 ` Preeti U Murthy
2013-05-06 5:22 ` Alex Shi
2013-05-06 12:03 ` Phil Carmody
2013-05-06 12:35 ` Alex Shi
2013-05-06 21:19 ` Paul Turner
2013-04-04 2:00 ` [patch v7 06/21] sched: add new sg/sd_lb_stats fields for incoming fork/exec/wake balancing Alex Shi
2013-04-04 2:00 ` [patch v7 07/21] sched: move sg/sd_lb_stats struct ahead Alex Shi
2013-04-04 2:00 ` [patch v7 08/21] sched: scale_rt_power rename and meaning change Alex Shi
2013-04-04 2:00 ` [patch v7 09/21] sched: get rq potential maximum utilization Alex Shi
2013-04-04 2:00 ` [patch v7 10/21] sched: add power aware scheduling in fork/exec/wake Alex Shi
2013-04-04 2:00 ` [patch v7 11/21] sched: add sched_burst_threshold_ns as wakeup burst indicator Alex Shi
2013-04-04 2:00 ` [patch v7 12/21] sched: using avg_idle to detect bursty wakeup Alex Shi
2013-04-04 2:00 ` [patch v7 13/21] sched: packing transitory tasks in wakeup power balancing Alex Shi
2013-04-04 2:00 ` [patch v7 14/21] sched: add power/performance balance allow flag Alex Shi
2013-04-04 2:00 ` [patch v7 15/21] sched: pull all tasks from source group Alex Shi
2013-04-04 5:59 ` Namhyung Kim
2013-04-06 11:49 ` Alex Shi
2013-04-04 2:00 ` [patch v7 16/21] sched: no balance for prefer_sibling in power scheduling Alex Shi
2013-05-06 3:26 ` Preeti U Murthy
2013-04-04 2:00 ` [patch v7 17/21] sched: add new members of sd_lb_stats Alex Shi
2013-04-04 2:00 ` [patch v7 18/21] sched: power aware load balance Alex Shi
2013-04-04 2:01 ` [patch v7 19/21] sched: lazy power balance Alex Shi
2013-04-04 2:01 ` [patch v7 20/21] sched: don't do power balance on share cpu power domain Alex Shi
2013-04-08 3:17 ` Preeti U Murthy
2013-04-08 3:25 ` Preeti U Murthy
2013-04-08 4:19 ` Alex Shi
2013-04-04 2:01 ` [patch v7 21/21] sched: make sure select_tas_rq_fair get a cpu Alex Shi
2013-04-11 21:02 ` [patch v7 0/21] sched: power aware scheduling Len Brown
2013-04-12 8:46 ` Alex Shi
2013-04-12 16:23 ` Borislav Petkov
2013-04-12 16:48 ` Mike Galbraith
2013-04-12 17:12 ` Borislav Petkov
2013-04-14 1:36 ` Alex Shi
2013-04-17 21:53 ` Len Brown
2013-04-18 1:51 ` Mike Galbraith
2013-04-26 15:11 ` Mike Galbraith
2013-04-30 5:16 ` Mike Galbraith
2013-04-30 8:30 ` Mike Galbraith
2013-04-30 8:41 ` Ingo Molnar
2013-04-30 9:35 ` Mike Galbraith
2013-04-30 9:49 ` Mike Galbraith
2013-04-30 9:56 ` Mike Galbraith
2013-05-17 8:06 ` Preeti U Murthy
2013-05-20 1:01 ` Alex Shi
2013-05-20 2:30 ` Preeti U Murthy
2013-04-14 1:28 ` Alex Shi
2013-04-14 5:10 ` Alex Shi
2013-04-14 15:59 ` Borislav Petkov
2013-04-15 6:04 ` Alex Shi
2013-04-15 6:16 ` Alex Shi
2013-04-15 9:52 ` Borislav Petkov
2013-04-15 13:50 ` Alex Shi
2013-04-15 23:12 ` Borislav Petkov
2013-04-16 0:22 ` Alex Shi
2013-04-16 10:24 ` Borislav Petkov
2013-04-17 1:18 ` Alex Shi
2013-04-17 7:38 ` Borislav Petkov
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