16.06.2021 11:51, Vincent Guittot пишет: > On Wed, 16 Jun 2021 at 10:39, Dmitry Osipenko <digetx@xxxxxxxxx> wrote: >> >> 16.06.2021 11:30, Vincent Guittot пишет: >>> On Wed, 16 Jun 2021 at 10:03, Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote: >>>> >>>> +Vincent. >>>> >>>> On 15-06-21, 22:32, Dmitry Osipenko wrote: >>>>> IIUC, the cpufreq already should be prepared for the case where firmware >>>>> may override frequency. Viresh, could you please clarify what are the >>>>> possible implications of the frequency overriding? >>>> >>>> The only implication is software would think hardware is running at >>>> some other frequency, while it is not. Not sure if something may break >>>> as a result of this. >>>> >>>> The scheduler's view of CPUs will not be same though, i.e. scheduler >>>> will see capacity as X, while in reality it has changed to Y. >>> >>> thermal_pressure is used by scheduler to balance the load between CPUs >>> according to the actual max frequency. If the thermal pressure doesn't >>> reflect reality, scheduler will end up enqueuing too many tasks on a >>> throttle CPU. >> >> What if all CPUs are throttled equally and running on the same >> frequency, will throttling have any effect on the scheduler decisions? > > Yes, the capacity is also used to detect when CPUs have spare capacity > or are already overloaded. We usually try to fill the spare capacity > of a CPU (CPU's max capacity - current utilization) but he max > capacity is reduced when the CPU is throttled, and the spare capacity > doesn't exist but scheduler could try to it > Thank you.
