On 02/19/2013 07:10 PM, Thomas Gleixner wrote: > On Tue, 19 Feb 2013, Daniel Lezcano wrote: >> I am working on identifying the different wakeup sources from the >> interrupts and I have a question regarding the timer broadcast. >> >> The broadcast timer is setup to the next event and that will wake up any >> idle cpu belonging to the "broadcast cpumask", right ? >> >> The cpu which has been woken up will look for each cpu the next-event >> and send an IPI to wake it up. >> >> Although, it is possible the sender of this IPI may not be concerned by >> the timer expiration and has been woken up just for sending the IPI, right ? > > Correct. > >> If this is correct, is it possible to setup the timer irq affinity to a >> cpu which will be concerned by the timer expiration ? so we prevent an >> unnecessary wake up for a cpu. > > It is possible, but we never implemented it. > > If we go there, we want to make that conditional on a property flag, > because some interrupt controllers especially on x86 only allow to > move the affinity from interrupt context, which is pointless.
Thanks Thomas for your quick answer. I will write a RFC patchset. -- Daniel -- <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | <http://twitter.com/#!/linaroorg> Twitter | <http://www.linaro.org/linaro-blog/> Blog -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
