On Thu, Mar 31, 2016 at 2:24 PM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > On Mon, Mar 28, 2016 at 11:17:44AM -0700, Steve Muckle wrote: >> The scenario I'm contemplating is that while a CPU-intensive task is >> running a thermal interrupt goes off. The driver for this thermal >> interrupt responds by capping fmax. If this happens just after the tick, >> it seems possible that we could wait a full tick before changing the >> frequency. Given a 10ms tick it could be rather annoying for thermal >> management algorithms on some platforms (I'm familiar with a few). > > So I'm blissfully unaware of all the thermal stuffs we have; but it > looks like its somehow bolten onto cpufreq without feedback. > > The thing I worry about is thermal scaling the CPU back past where RT/DL > tasks can still complete in time. It should not be able to do that, or > rather, missing deadlines because thermal is about as useful as > rebooting the device. Right. If thermal throttling kicks in, the game is pretty much over. That's why ideas float about taking the thermal constraints into account upfront, but that's a different discussion entirely. > I guess I'm saying is, the whole cpufreq/thermal 'interface' needs work > anyhow. Yes, it does. -- 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
