On 29-Oct 18:33, Patrick Bellasi wrote:
[...]
> +#ifdef CONFIG_UCLAMP_TASK
> +/**
> + * clamp_util: clamp a utilization value for a specified CPU
> + * @rq: the CPU's RQ to get the clamp values from
> + * @util: the utilization signal to clamp
> + *
> + * Each CPU tracks util_{min,max} clamp values depending on the set of its
> + * currently RUNNABLE tasks. Given a utilization signal, i.e a signal in
> + * the [0..SCHED_CAPACITY_SCALE] range, this function returns a clamped
> + * utilization signal considering the current clamp values for the
> + * specified CPU.
> + *
> + * Return: a clamped utilization signal for a given CPU.
> + */
> +static inline unsigned int uclamp_util(struct rq *rq, unsigned int util)
> +{
> + unsigned int min_util = rq->uclamp.value[UCLAMP_MIN];
> + unsigned int max_util = rq->uclamp.value[UCLAMP_MAX];
Just notice here we can have an issue.
For each scheduling entity, we always ensure that:
util_min <= util_max
However, since CPU's {min,max}_util clamps are always MAX aggregated
considering the corresponding clamps of RUNNABLE tasks with
_different_ clamps, we can end up with CPU clamps where:
util_min > util_max
Thus, we need to add the following sanity check here:
+ if (unlikely(min_util > max_util))
+ return min_util;
> +
> + return clamp(util, min_util, max_util);
> +}
--
#include <best/regards.h>
Patrick Bellasi
