sched/fair: consider task utilization in group_norm_util()
The group_norm_util() function is used to compute the normalized utilization of a SG given a certain energy_env configuration. The main client of this function is the energy_diff function when it comes to compute the SG energy for one of the before/after scheduling candidates. Currently, the energy_diff function sets util_delta = 0 when it wants to compute the energy corresponding to the scheduling candidate where the task runs in the previous CPU. This implies that, for the task waking up in the previous CPU we consider only its blocked load tracked by the CPU RQ. However, in case of a medium-big task which is waking up on a long time idle CPU, this blocked load can be already completely decayed. More in general, the current approach is biased towards under-estimating the energy consumption for the "before" scheduling candidate. This patch fixes this by: - always use the cpu_util_wake() to properly get the utilization of a CPU without any (partially decayed) contribution of the waking up task - adding the task utilization to the cpu_util_wake just for the target cpu The "target CPU" is defined by the energy_env to be either the src_cpu or the dst_cpu, depending on which scheduling candidate we are considering. This patch update also the definition of __cpu_norm_util(), which is currently called just by the group_norm_util() function. This allows to simplify the code by using this function just to normalize a specified utilization with respect to a given capacity. This update allows to completely remove any dependency of group_norm_util() from calc_util_delta(). Change-Id: I3b6ec50ce8decb1521faae660e326ab3319d3c82 Signed-off-by:Patrick Bellasi <patrick.bellasi@arm.com> Signed-off-by:
Chris Redpath <chris.redpath@arm.com> (cherry picked from commit ef34ea830347ca175ba8a1baf05357ed98d5728c) Signed-off-by:
Quentin Perret <quentin.perret@arm.com>
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