linux-kernel - Re: [PATCH] sched/fair: Remove cfs_rq::nr_spread_over and cfs_rq::exec

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Message-ID: <9b0b69bf-dac0-457d-a4dc-4bea18eecc43@linux.dev>
Date: Wed, 17 Jul 2024 19:25:50 +0800
From: Chengming Zhou <chengming.zhou@...ux.dev>
To: Vishal Chourasia <vishalc@...ux.ibm.com>,
 Chuyi Zhou <zhouchuyi@...edance.com>
Cc: mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
 vincent.guittot@...aro.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sched/fair: Remove cfs_rq::nr_spread_over and
 cfs_rq::exec_clock

On 2024/7/17 19:07, Vishal Chourasia wrote:
> On Tue, Jul 16, 2024 at 11:06:34PM +0800, Chuyi Zhou wrote:
>> cfs_rq::nr_spread_over and cfs_rq::exec_clock are not used anymore in
>> eevdf. Remove them from struct cfs_rq.
>>
> 
> nr_spread_over tracks the number of instances where the difference
> between a scheduling entity's virtual runtime and the minimum virtual
> runtime in the runqueue exceeds three times the scheduler latency,
> indicating significant disparity in task scheduling.
> Commit that removed its usage: 5e963f2bd: sched/fair: Commit to EEVDF
> 
> 
> cfs_rq->exec_clock was used to account for time spent executing tasks.
> Commit that removed its usage: 5d69eca542ee1 sched: Unify runtime
> accounting across classes
> 
>> Signed-off-by: Chuyi Zhou <zhouchuyi@...edance.com>
> 
> Acked-by: Vishal Chourasia <vishalc@...ux.ibm.com>

Looks good to me! Maybe it's better to add these to your changelog.

Reviewed-by: Chengming Zhou <chengming.zhou@...ux.dev>

Thanks.

>> ---
>>   kernel/sched/debug.c | 4 ----
>>   kernel/sched/sched.h | 6 ------
>>   2 files changed, 10 deletions(-)
>>
>> diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
>> index c1eb9a1afd13..90c4a9998377 100644
>> --- a/kernel/sched/debug.c
>> +++ b/kernel/sched/debug.c
>> @@ -641,8 +641,6 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
>>   	SEQ_printf(m, "\n");
>>   	SEQ_printf(m, "cfs_rq[%d]:\n", cpu);
>>   #endif
>> -	SEQ_printf(m, "  .%-30s: %Ld.%06ld\n", "exec_clock",
>> -			SPLIT_NS(cfs_rq->exec_clock));
>>   
>>   	raw_spin_rq_lock_irqsave(rq, flags);
>>   	root = __pick_root_entity(cfs_rq);
>> @@ -669,8 +667,6 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
>>   			SPLIT_NS(right_vruntime));
>>   	spread = right_vruntime - left_vruntime;
>>   	SEQ_printf(m, "  .%-30s: %Ld.%06ld\n", "spread", SPLIT_NS(spread));
>> -	SEQ_printf(m, "  .%-30s: %d\n", "nr_spread_over",
>> -			cfs_rq->nr_spread_over);
>>   	SEQ_printf(m, "  .%-30s: %d\n", "nr_running", cfs_rq->nr_running);
>>   	SEQ_printf(m, "  .%-30s: %d\n", "h_nr_running", cfs_rq->h_nr_running);
>>   	SEQ_printf(m, "  .%-30s: %d\n", "idle_nr_running",
>> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
>> index 4c36cc680361..8a071022bdec 100644
>> --- a/kernel/sched/sched.h
>> +++ b/kernel/sched/sched.h
>> @@ -599,7 +599,6 @@ struct cfs_rq {
>>   	s64			avg_vruntime;
>>   	u64			avg_load;
>>   
>> -	u64			exec_clock;
>>   	u64			min_vruntime;
>>   #ifdef CONFIG_SCHED_CORE
>>   	unsigned int		forceidle_seq;
>> @@ -619,10 +618,6 @@ struct cfs_rq {
>>   	struct sched_entity	*curr;
>>   	struct sched_entity	*next;
>>   
>> -#ifdef	CONFIG_SCHED_DEBUG
>> -	unsigned int		nr_spread_over;
>> -#endif
>> -
>>   #ifdef CONFIG_SMP
>>   	/*
>>   	 * CFS load tracking
>> @@ -1158,7 +1153,6 @@ struct rq {
>>   	/* latency stats */
>>   	struct sched_info	rq_sched_info;
>>   	unsigned long long	rq_cpu_time;
>> -	/* could above be rq->cfs_rq.exec_clock + rq->rt_rq.rt_runtime ? */
>>   
>>   	/* sys_sched_yield() stats */
>>   	unsigned int		yld_count;
>> -- 
>> 2.20.1
>>