linux-kernel - Re: [PATCH v4 3/3] sched/tp: Add new tracepoint to track compute energy computation

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Message-ID: <671ff8bf-ed3e-b651-d9da-6507fddee010@arm.com>
Date:   Wed, 23 Aug 2023 12:30:27 +0200
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Qais Yousef <qyousef@...alina.io>, Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Vincent Guittot <vincent.guittot@...aro.org>
Cc:     linux-kernel@...r.kernel.org, Lukasz Luba <lukasz.luba@....com>,
        Wei Wang <wvw@...gle.com>, Xuewen Yan <xuewen.yan94@...il.com>,
        Hank <han.lin@...iatek.com>,
        Jonathan JMChen <Jonathan.JMChen@...iatek.com>,
        Hongyan Xia <hongyan.xia2@....com>
Subject: Re: [PATCH v4 3/3] sched/tp: Add new tracepoint to track compute
 energy computation

On 22/08/2023 00:45, Qais Yousef wrote:
> It was useful to track feec() placement decision and debug the spare
> capacity and optimization issues vs uclamp_max.
> 
> Signed-off-by: Qais Yousef (Google) <qyousef@...alina.io>
> ---
>  include/trace/events/sched.h | 5 +++++
>  kernel/sched/core.c          | 1 +
>  kernel/sched/fair.c          | 7 ++++++-
>  3 files changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
> index fbb99a61f714..a13d5d06be9d 100644
> --- a/include/trace/events/sched.h
> +++ b/include/trace/events/sched.h
> @@ -735,6 +735,11 @@ DECLARE_TRACE(sched_update_nr_running_tp,
>  	TP_PROTO(struct rq *rq, int change),
>  	TP_ARGS(rq, change));
>  
> +DECLARE_TRACE(sched_compute_energy_tp,
> +	TP_PROTO(struct task_struct *p, int dst_cpu, unsigned long energy,
> +		 unsigned long max_util, unsigned long busy_time),
> +	TP_ARGS(p, dst_cpu, energy, max_util, busy_time));
> +
>  #endif /* _TRACE_SCHED_H */
>  
>  /* This part must be outside protection */
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index efe3848978a0..36c60ad9966a 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -114,6 +114,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(sched_overutilized_tp);
>  EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_cfs_tp);
>  EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_se_tp);
>  EXPORT_TRACEPOINT_SYMBOL_GPL(sched_update_nr_running_tp);
> +EXPORT_TRACEPOINT_SYMBOL_GPL(sched_compute_energy_tp);
>  
>  DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
>  
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index e19a36e7b433..779c285203e3 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -7604,11 +7604,16 @@ compute_energy(struct energy_env *eenv, struct perf_domain *pd,
>  {
>  	unsigned long max_util = eenv_pd_max_util(eenv, pd_cpus, p, dst_cpu);
>  	unsigned long busy_time = eenv->pd_busy_time;
> +	unsigned long energy;
>  
>  	if (dst_cpu >= 0)
>  		busy_time = min(eenv->pd_cap, busy_time + eenv->task_busy_time);
>  
> -	return em_cpu_energy(pd->em_pd, max_util, busy_time, eenv->cpu_cap);
> +	energy = em_cpu_energy(pd->em_pd, max_util, busy_time, eenv->cpu_cap);
> +
> +	trace_sched_compute_energy_tp(p, dst_cpu, energy, max_util, busy_time);
> +
> +	return energy;
>  }
>  
>  /*

I will make sure that this gets integrated into our trace module in Lisa
https://github.com/ARM-software/lisa .

Reviewed-by: Dietmar Eggemann <dietmar.eggemann@....com>