linux-kernel - Re: [PATCH V4] irq: Track the interrupt timings

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Message-ID: <20160503134403.GB19298@linaro.org>
Date:	Tue, 3 May 2016 15:44:03 +0200
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	tglx@...utronix.de
Cc:	nicolas.pitre@...aro.org, shreyas@...ux.vnet.ibm.com,
	linux-kernel@...r.kernel.org, peterz@...radead.org,
	rafael@...nel.org, vincent.guittot@...aro.org
Subject: Re: [PATCH V4] irq: Track the interrupt timings

On Wed, Apr 13, 2016 at 01:05:56PM +0200, Daniel Lezcano wrote:
> The interrupt framework gives a lot of information about each interrupt.
> 
> It does not keep track of when those interrupts occur though.
> 
> This patch provides a mean to record the elapsed time between successive
> interrupt occurrences in a per-IRQ per-CPU circular buffer to help with the
> prediction of the next occurrence using a statistical model.
> 
> A new function is added to browse the different interrupts and retrieve the
> timing information stored in it.
> 
> A static key is introduced so when the irq prediction is switched off at
> runtime, we can reduce the overhead near to zero. The irq timings is
> supposed to be potentially used by different sub-systems and for this reason
> the static key is a ref counter, so when the last use releases the irq
> timings that will result on the effective deactivation of the irq measurement.
> 
> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
> Acked-by: Nicolas Pitre <nicolas.pitre@...aro.org>
> ---
> V4:
>   - Added a static key
>   - Added more comments for irq_timings_get_next()
>   - Unified some function names to be prefixed by 'irq_timings_...'
>   - Fixed a rebase error

Hi Thomas,

I believe all the comments were addressed.

I can imagine you are very busy at the moment. Is there something else I 
should fix or is the patch ok for you ?

Thanks.

  -- Daniel