On 03/19/2014 10:33 AM, Viresh Kumar wrote: > On 18 March 2014 17:46, Srivatsa S. Bhat > <[email protected]> wrote: >> Agreed. As far as I understand, for ->target drivers, today we use GOV_STOP >> to stop managing the CPU going offline. And for ->setpolicy drivers, we will >> use this new callback to achieve the same goal. > > So a better question would be: What's the purpose of ->stop() call for a > policy?
Ideally, it should remove the outgoing CPU from the policy and "stop managing that CPU", whatever that means to the driver (for intel_pstate, it means setting it to min P state and destroying the timer). > Stop managing CPUs of that policy? Stop managing only the particular CPU going offline. IOW, we should somehow communicate to the ->stop() callback that we are taking CPU 'x' offline. If adding a ->stop() callback in the cpufreq_driver is not the best way to achieve it, then lets think of an alternative. The way I look at it, this new mechanism what we want, should allow ->setpolicy drivers to do what the GOV_STOP will do for regular drivers. That is, allow it to "shutdown the CPU from a cpufreq perspective", whatever that means to the driver. We can think of a completely different way of achieving it, if ->stop() is not suitable for that purpose. > Or even do something on CPUs of a policy > before CPUs are offlined? > > Probably in the current solution Dirk is doing both these things.. > > And so I thought maybe its better not to restrict ->stop() to just > setpolicy() drivers. Regards, Srivatsa S. Bhat -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
