Hi,
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 ?
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.
For example, let's say we have a 2 cpus system.
cpu0, cpu1 are idle
The next event is for cpu1 but cpu0 is wake up by the broadcast timer, after checking it has nothing to do except send a IPI_TIMER to cpu1 and then goes to idle again.
Wouldn't be worth to set the broadcast timer affinity to cpu1, so cpu0 is not wake up ?
Did I missed something or does it sound correct ?
Thanks -- Daniel