Re: [PATCH 19/20 -v5] Trace irq disabled critical timings

[Steven Rostedt]

On Wed, 23 Jan 2008, Frank Ch. Eigler wrote:
> On Wed, Jan 23, 2008 at 12:11:07PM -0500, Steven Rostedt wrote:
> > This patch adds latency tracing for critical timings
> > (how long interrupts are disabled for).
> > [...]
>
> Is there an opportunity here to share effort with latencytop, and
> ideally to use markers as much as possible for these event hooks?

Well, I just found out about latencytop a couple of days ago when Arjan
announced it. I took a quick look and it seems to be more of a general
collection of information. This tracer pinpoints out specific maxes.
Although I may be wrong (I have to admit, I haven't had the time to really
look at what LatencyTop does, but I have been using this tracer in -rt for
a number of years).

As for using markers, I just piggied back on top of lockdep, since it has
the same hooks that I needed. If we were to replace them with markers,
then I would say lockdep should use the markers too.

One thing about markers, only one probe may be allowed at a time. Perhaps
we should fix this by using something like I did with the mcount hook.

-- Steve

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