On Friday 07 Sep 2018 at 10:56:12 (+0200), Rafael J. Wysocki wrote: > On Friday, September 7, 2018 10:52:01 AM CEST Rafael J. Wysocki wrote: > > On Thursday, September 6, 2018 4:38:44 PM CEST Quentin Perret wrote: > > > Hi Rafael, > > > > > > On Thursday 06 Sep 2018 at 11:18:55 (+0200), Rafael J. Wysocki wrote: > > > > I'm not a particular fan of notifiers to be honest and you don't need > > > > to add an extra chain just in order to be able to register a callback > > > > from a single user. > > > > > > Right. I agree there are alternatives to using notifiers. I used them > > > because they're existing infrastructure, and because they let me do what > > > I want without too much troubles, which are two important points. > > > > > > > That can be achieved with a single callback > > > > pointer too, but also you could just call a function exported by the > > > > scheduler directly from where in the cpufreq code it needs to be > > > > called. > > > > > > Are you thinking about something comparable to what is done in > > > cpufreq_add_update_util_hook() (kernel/sched/cpufreq.c) for example ? > > > That would probably have the same drawback as my current implementation, > > > that is that the scheduler is notified of _all_ governor changes, not > > > only changes to/from sugov although this is the only thing we care about > > > for EAS. > > > > Well, why don't you implement it as something like "if the governor changes > > from sugov to something else (or the other way around), call this function > > from the scheduler"?
Yes that work too ... > That said, governors are stopped and started in a few cases other than just > changing the governor, so maybe you want the EAS side to be notified whenever > sugov is stopped and started after all? Right, so sugov_start/sugov_stop could be an option in this case ... And that would leave the CPUFreq core untouched. I'll try to write something :-) Thanks, Quentin
