From: Valentin Schneider <valentin.schneider@arm.com>
To: Vincent Guittot <vincent.guittot@linaro.org>,
mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com,
dietmar.eggemann@arm.com, rostedt@goodmis.org,
bsegall@google.com, mgorman@suse.de,
linux-kernel@vger.kernel.org
Cc: pauld@redhat.com, parth@linux.ibm.com
Subject: Re: [RFC 4/4] sched/fair: Take into runnable_avg to classify group
Date: Thu, 13 Feb 2020 18:32:46 +0000 [thread overview]
Message-ID: <94eae44f-7608-936d-4fde-dcf93cfa6b9b@arm.com> (raw)
In-Reply-To: <20200211174651.10330-5-vincent.guittot@linaro.org>
On 2/11/20 5:46 PM, Vincent Guittot wrote:
> Take into account the new runnable_avg signal to classify a group and to
> mitigate the volatility of util_avg in face of intensive migration.
>
> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
> ---
> kernel/sched/fair.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 7d7cb207be30..5f8f12c902d4 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -7691,6 +7691,7 @@ struct sg_lb_stats {
> unsigned long group_load; /* Total load over the CPUs of the group */
> unsigned long group_capacity;
> unsigned long group_util; /* Total utilization of the group */
> + unsigned long group_runnable; /* Total utilization of the group */
^^^^^^^^^^^
"Total runnable" hurts my eyes, but in any case this shouldn't be just
"utilization".
> unsigned int sum_nr_running; /* Nr of tasks running in the group */
> unsigned int sum_h_nr_running; /* Nr of CFS tasks running in the group */
> unsigned int idle_cpus;
> @@ -7911,6 +7912,10 @@ group_has_capacity(unsigned int imbalance_pct, struct sg_lb_stats *sgs)
> if (sgs->sum_nr_running < sgs->group_weight)
> return true;
>
> + if ((sgs->group_capacity * imbalance_pct) <
> + (sgs->group_runnable * 100))
> + return false;
> +
I haven't stared long enough at patch 2, but I'll ask anyway - with this new
condition, do we still need the next one (based on util)? AIUI
group_runnable is >= group_util, so if group_runnable is within the allowed
margin then group_util has to be as well.
> if ((sgs->group_capacity * 100) >
> (sgs->group_util * imbalance_pct))
> return true;
> @@ -7936,6 +7941,10 @@ group_is_overloaded(unsigned int imbalance_pct, struct sg_lb_stats *sgs)
> (sgs->group_util * imbalance_pct))
> return true;
>
> + if ((sgs->group_capacity * imbalance_pct) <
> + (sgs->group_runnable * 100))
> + return true;
> +
Ditto on the group_runnable >= group_util - we could get rid of the check
above this one.
> return false;
> }
>
> @@ -8030,6 +8039,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
>
> sgs->group_load += cpu_load(rq);
> sgs->group_util += cpu_util(i);
> + sgs->group_runnable += cpu_runnable(rq);
> sgs->sum_h_nr_running += rq->cfs.h_nr_running;
>
> nr_running = rq->nr_running;
>
next prev parent reply other threads:[~2020-02-13 18:32 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-11 17:46 [PATCH 0/4] remove runnable_load_avg and improve group_classify Vincent Guittot
2020-02-11 17:46 ` [PATCH 1/4] sched/fair: reorder enqueue/dequeue_task_fair path Vincent Guittot
2020-02-12 13:20 ` Mel Gorman
2020-02-12 14:47 ` Vincent Guittot
2020-02-12 16:11 ` Mel Gorman
2020-02-11 17:46 ` [RFC 2/4] sched/numa: replace runnable_load_avg by load_avg Vincent Guittot
2020-02-12 13:37 ` Mel Gorman
2020-02-12 15:03 ` Vincent Guittot
2020-02-12 16:04 ` Mel Gorman
2020-02-12 19:49 ` Mel Gorman
2020-02-12 21:29 ` Mel Gorman
2020-02-13 8:05 ` Vincent Guittot
2020-02-13 9:24 ` Mel Gorman
[not found] ` <20200213131658.9600-1-hdanton@sina.com>
2020-02-13 13:46 ` Mel Gorman
2020-02-13 15:00 ` Phil Auld
2020-02-13 15:14 ` Mel Gorman
2020-02-13 16:11 ` Vincent Guittot
2020-02-13 16:34 ` Mel Gorman
2020-02-13 16:38 ` Vincent Guittot
2020-02-13 17:02 ` Mel Gorman
2020-02-13 17:15 ` Vincent Guittot
2020-02-11 17:46 ` [RFC 3/4] sched/fair: replace runnable load average by runnable average Vincent Guittot
2020-02-12 14:30 ` Mel Gorman
2020-02-14 7:42 ` Vincent Guittot
2020-02-13 17:36 ` Peter Zijlstra
2020-02-14 7:43 ` Vincent Guittot
2020-02-11 17:46 ` [RFC 4/4] sched/fair: Take into runnable_avg to classify group Vincent Guittot
2020-02-13 18:32 ` Valentin Schneider [this message]
2020-02-13 18:37 ` Valentin Schneider
2020-02-14 7:48 ` Vincent Guittot
2020-02-11 21:04 ` [PATCH 0/4] remove runnable_load_avg and improve group_classify Mel Gorman
2020-02-12 8:16 ` Vincent Guittot
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