From: Thomas Gleixner <tglx@linutronix.de>
To: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: John Stultz <john.stultz@linaro.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"linaro-dev >> Lists Linaro-dev" <linaro-dev@lists.linaro.org>
Subject: Re: [resend] Timer broadcast question
Date: Tue, 19 Feb 2013 19:10:06 +0100 (CET) [thread overview]
Message-ID: <alpine.LFD.2.02.1302191904560.22263@ionos> (raw)
In-Reply-To: <5123BE35.8070902@linaro.org>
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,
tglx
next prev parent reply other threads:[~2013-02-19 18:10 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-19 18:02 Daniel Lezcano
2013-02-19 18:10 ` Thomas Gleixner [this message]
2013-02-19 18:21 ` Daniel Lezcano
2013-02-19 22:46 ` Andy Lutomirski
2013-02-20 10:09 ` Thomas Gleixner
2013-02-21 6:19 ` Santosh Shilimkar
2013-02-21 9:01 ` Daniel Lezcano
2013-02-21 9:14 ` Santosh Shilimkar
2013-02-21 22:01 ` [PATCH 1/2] time : pass broadcast device parameter Daniel Lezcano
2013-02-21 22:01 ` [PATCH 2/2][RFC] time : set broadcast irq affinity Daniel Lezcano
2013-02-22 17:55 ` Jacob Pan
2013-02-22 18:45 ` Thomas Gleixner
2013-02-25 22:50 ` Daniel Lezcano
2013-02-25 23:00 ` Jacob Pan
2013-02-26 8:45 ` [PATCH 1/2] time : pass broadcast device parameter Viresh Kumar
2013-02-26 11:30 ` Daniel Lezcano
2013-02-26 11:31 ` Daniel Lezcano
2013-02-26 12:14 ` Viresh Kumar
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