Re: [PATCH 1/2] sched/fair: Add cfs bandwidth burst statistics

[Daniel Jordan]

On Mon, Aug 16, 2021 at 03:08:48PM +0800, Huaixin Chang wrote:
> Two new statistics are introduced to show the internal of burst feature
> and explain why burst helps or not.
> 
> nr_bursts:  number of periods bandwidth burst occurs
> burst_usec: cumulative wall-time that any cpus has
> 	    used above quota in respective periods
> 
> Co-developed-by: Shanpei Chen <shanpeic@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Shanpei Chen <shanpeic@xxxxxxxxxxxxxxxxx>
> Co-developed-by: Tianchen Ding <dtcccc@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Tianchen Ding <dtcccc@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Huaixin Chang <changhuaixin@xxxxxxxxxxxxxxxxx>
> Acked-by: Tejun Heo <tj@xxxxxxxxxx>
> ---
>  kernel/sched/core.c  | 13 ++++++++++---
>  kernel/sched/fair.c  |  9 +++++++++
>  kernel/sched/sched.h |  3 +++
>  3 files changed, 22 insertions(+), 3 deletions(-)
> 
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 2d9ff40f4661..9a286c8a1354 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -10088,6 +10088,9 @@ static int cpu_cfs_stat_show(struct seq_file *sf, void *v)
>  		seq_printf(sf, "wait_sum %llu\n", ws);
>  	}
>  
> +	seq_printf(sf, "nr_bursts %d\n", cfs_b->nr_burst);
> +	seq_printf(sf, "burst_usec %llu\n", cfs_b->burst_time);

burst_time is nsec, not usec.

Just "burst_time" seems the way to go for consistency with
throttled_time in the same file, though "burst_usec" nicely has units
and would have the same name between cgroup1 and 2.