Re: [PATCH v3 2/6] cpufreq: schedutil: ensure max frequency while running RT/DL tasks

From: Juri Lelli
Date: Thu Nov 30 2017 - 08:18:10 EST


Hi,

On 30/11/17 11:47, Patrick Bellasi wrote:

[...]

> @@ -340,6 +349,7 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time,
> struct sugov_policy *sg_policy = sg_cpu->sg_policy;
> unsigned long util, max;
> unsigned int next_f;
> + bool rt_mode;
>
> sugov_get_util(&util, &max, sg_cpu->cpu);
>
> @@ -353,17 +363,27 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time,
> sg_cpu->flags = 0;
> goto done;
> }
> - sg_cpu->flags = flags;
> +
> + /*
> + * While RT/DL tasks are running we do not want FAIR tasks to
> + * overwrite this CPU's flags, still we can update utilization and
> + * frequency (if required/possible) to be fair with these tasks.
> + */
> + rt_mode = task_has_dl_policy(current) ||
> + task_has_rt_policy(current) ||
> + (flags & SCHED_CPUFREQ_RT_DL);
> + if (rt_mode)
> + sg_cpu->flags |= flags;
> + else
> + sg_cpu->flags = flags;
>
> sugov_set_iowait_boost(sg_cpu, time, flags);
> sg_cpu->last_update = time;
>
> if (sugov_should_update_freq(sg_policy, time)) {
> - if (flags & SCHED_CPUFREQ_RT_DL)
> - next_f = sg_policy->policy->cpuinfo.max_freq;
> - else
> - next_f = sugov_next_freq_shared(sg_cpu, time);
> -
> + next_f = rt_mode
> + ? sg_policy->policy->cpuinfo.max_freq
> + : sugov_next_freq_shared(sg_cpu, time);
> sugov_update_commit(sg_policy, time, next_f);

Aren't we already at max_freq at this point (since an RT/DL task is
running)? Do we need to trigger a frequency update?

Best,

Juri