From: Juri Lelli <juri.lelli@arm.com>
To: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org,
Vincent Guittot <vincent.guittot@linaro.org>,
Ben Segall <bsegall@google.com>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Yuyang Du <yuyang.du@intel.com>
Subject: Re: [RFC PATCH 1/3] sched/fair: Aggregate task utilization only on root cfs_rq
Date: Thu, 2 Jun 2016 10:23:58 +0100 [thread overview]
Message-ID: <20160602092358.GC9340@e106622-lin> (raw)
In-Reply-To: <1464809962-25814-2-git-send-email-dietmar.eggemann@arm.com>
Hi,
minor comment below.
On 01/06/16 20:39, Dietmar Eggemann wrote:
> cpu utilization (cpu_util()) is defined as the cpu (original) capacity
> capped cfs_rq->avg->util_avg signal of the root cfs_rq.
>
> With the current pelt version, the utilization of a task [en|de]queued
> on/from a cfs_rq, representing a task group other than the root task group
> on a cpu, is not immediately propagated down to the root cfs_rq.
>
> This makes decisions based on cpu_util() for scheduling or cpu frequency
> settings less accurate in case tasks are running in task groups.
>
> This patch aggregates the task utilization only on the root cfs_rq,
> essentially avoiding maintaining utilization for a se/cfs_rq representing
> task groups other than the root task group (!entity_is_task(se) and
> &rq_of(cfs_rq)->cfs != cfs_rq).
>
> The additional if/else condition to set @update_util in
> __update_load_avg() is replaced in 'sched/fair: Change @running of
> __update_load_avg() to @update_util' by providing the information whether
> utilization has to be maintained via an argument to this function.
>
> The additional requirements for the alignment of the last_update_time of a
> se and the root cfs_rq are handled by the patch 'sched/fair: Sync se with
> root cfs_rq'.
>
> Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
> ---
> kernel/sched/fair.c | 48 ++++++++++++++++++++++++++++++++++++------------
> 1 file changed, 36 insertions(+), 12 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 218f8e83db73..212becd3708f 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -2705,6 +2705,7 @@ __update_load_avg(u64 now, int cpu, struct sched_avg *sa,
> u32 contrib;
> unsigned int delta_w, scaled_delta_w, decayed = 0;
> unsigned long scale_freq, scale_cpu;
> + int update_util = 0;
>
> delta = now - sa->last_update_time;
> /*
> @@ -2725,6 +2726,12 @@ __update_load_avg(u64 now, int cpu, struct sched_avg *sa,
> return 0;
> sa->last_update_time = now;
>
> + if (cfs_rq) {
> + if (&rq_of(cfs_rq)->cfs == cfs_rq)
Maybe we can wrap this sort of checks in a static inline improving
readability?
Best,
- Juri
next prev parent reply other threads:[~2016-06-02 9:23 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-01 19:39 [RFC PATCH 0/3] Aggregate task utilization only on root cfs_rq Dietmar Eggemann
2016-06-01 19:39 ` [RFC PATCH 1/3] sched/fair: " Dietmar Eggemann
2016-06-02 9:23 ` Juri Lelli [this message]
2016-06-02 15:53 ` Dietmar Eggemann
2016-06-02 16:11 ` Juri Lelli
2016-06-01 19:39 ` [RFC PATCH 2/3] sched/fair: Sync se with " Dietmar Eggemann
2016-06-06 2:59 ` Leo Yan
2016-06-06 8:45 ` Dietmar Eggemann
2016-06-06 12:11 ` Vincent Guittot
2016-06-01 19:39 ` [RFC PATCH 3/3] sched/fair: Change @running of __update_load_avg() to @update_util Dietmar Eggemann
2016-06-01 20:11 ` Peter Zijlstra
2016-06-02 15:59 ` Dietmar Eggemann
2016-06-02 9:25 ` Juri Lelli
2016-06-02 17:27 ` Dietmar Eggemann
2016-06-03 10:56 ` Juri Lelli
2016-06-01 20:10 ` [RFC PATCH 0/3] Aggregate task utilization only on root cfs_rq Peter Zijlstra
2016-06-02 15:40 ` Dietmar Eggemann
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