On Mon, Mar 7, 2016 at 2:32 PM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > On Mon, Mar 07, 2016 at 02:15:47PM +0100, Rafael J. Wysocki wrote: >> On Mon, Mar 7, 2016 at 9:00 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > >> > Sure I know all that. But that, to me, seems like an argument for why >> > you should have done this a long time ago. >> >> While I generally agree with this, I don't quite see why cleaning that >> up necessarily has to be connected to the current patch series which >> is my point. > > Ah OK, fair enough I suppose. But someone should stick this on their > TODO list, we should not 'forget' about this (again). Sure. >> > But I do think something wants to be done here. >> >> So here's what I can do for the "fast switch" thing. >> >> There is the fast_switch_possible policy flag that's necessary anyway. >> I can make notifier registration fail when that is set for at least >> one policy and I can make the setting of it fail if at least one >> notifier has already been registered. >> >> However, without spending too much time on chasing code dependencies i >> sort of suspect that it will uncover things that register cpufreq >> notifiers early and it won't be possible to use fast switch without >> sorting that out. > > The two x86 users don't register notifiers when CONSTANT_TSC, which > seems to be the right thing. > > Much of the other users seem unlikely to be used on x86, so I suspect > the initial fallout will be very limited. OK, let me try this then. > *groan* modules, cpufreq allows drivers to be modules, so init sequences > are poorly defined at best :/ Yes that blows. Yup. >> And that won't even change anything apart from >> removing some code that has not worked for quite a while already and >> nobody noticed. > > Which is always a good thing, but yes, we can do this later. > >> It is doable for the "fast switch" thing, but it won't help in all of >> the other cases when notifications are not reliable. > > Right, you can maybe add a 'NOTIFIERS_BROKEN' flag to the intel_p_state > and HWP drivers or so, and trigger off of that. Something like that, yes. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
