Re: [PATCH] gpio: add trace events for setting direction and value

From: Grant Likely
Date: Wed Mar 02 2011 - 17:03:14 EST


On Fri, Feb 18, 2011 at 10:48:06AM -0500, Steven Rostedt wrote:
> On Fri, 2011-02-18 at 10:58 +0100, Uwe Kleine-König wrote:
> > Hi Steven, hi Grant,
> >
> > On Wed, Feb 16, 2011 at 12:12:51PM -0500, Steven Rostedt wrote:
> > > Note: to save the memory footprint of these tracepoints, you can use
> > > DEFINE_EVENT_PRINT(). You can see the usage for this in the
> > > include/trace/events/kmem.h.
> > > But to do this, you will need to have a single TP_STRUCT__entry() for
> > > both. Not sure if this is what you want.
> > >
> > > TP_STRUCT__entry(
> > > __field(unsigned, gpiq)
> > > __field(int, get_in)
> > > __field(int, value_err)
> > >
> > > ??
> > >
> > > Just a suggestion, but may not be worth it.
> > Yeah, I saw that, still I think it's sane to keep them seperated.
> > Or how much would we save? Can you estimate that?
>
> You can do it :) Especially since it can vary by archs.
>
> Just compile the kernel once this way, and then try it with
> DEFINE_EVENT_PRINT(), compile the kernel and run size on the two.
>
> Then you can see the difference it makes. It may end up not being worth
> the difference. But as embedded uses gpio the most, I'll leave that up
> to you.

Uwe, any update on this? Are you going to spin a new patch, or should
I take this one?

g.
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