linux-kernel - Timer broadcast question

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Message-ID: <51238628.7000000@linaro.org>
Date:	Tue, 19 Feb 2013 15:03:20 +0100
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	John Stultz <john.stultz@...aro.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Timer broadcast question

Hi John, Frederic,

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
cpu, right ?

The time framework will look at the different cpus next-event and send
them an IPI to wake them 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.

Did I missed something or does it sound correct ?

Thanks
  -- Daniel

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