On Thursday, January 12, 2012, Antti P Miettinen wrote: > "Rafael J. Wysocki" <rjw@xxxxxxx> writes: > >> By blocking sleep states we can address "system level latency" or "best case > >> latency" but as far as I can see PM QoS does not address "worst case > >> latency". > > > > I'm not sure what you mean by "worst case latency". > > Umm.. the usual concept. If latency is the time from stimulus to > response, this time can vary based on context. One part of the context > is the hardware state but there is also the system load. So for example > the time from interrupt to display being updated is affected by hardware > state but also system load. As far as I understand, current PM QoS > latency requests addresses hardware state but do not account for > possible resource contention, e.g. several latency sensitive clients > (device drivers, tasks) competing for CPU. In this sense minimum CPU > frequency requests would be similar. That's correct, we don't take possible contention into account in PM QoS, because such conditions may happen idependently of power management anyway. Thanks, Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/linux-pm
