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SubjectRe: [GIT PULL] tracing: make signal tracepoints more useful
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On Mon, 2012-01-16 at 08:45 +0100, Ingo Molnar wrote:

> Looks good to me at a first (quick) sight, except this bit
> which changes the ABI:
>
> > > - TP_printk("sig=%d errno=%d code=%d comm=%s pid=%d",
> > > + TP_printk("sig=%d errno=%d code=%d comm=%s pid=%d grp=%d res=%d",
>
> That's not how we change tracepoints generally - we add a new
> one and eventually phase out the old one. Which apps/tools rely
> on the old tracepoint? If it's exactly zero apps then we might
> be able to change it, but this needs to be investigated.

But this tracepoint wasn't changed, it was added on to. There's a
difference. Any tool that uses this (including something like powertop)
should be able to handle it. It should be no different than adding
to /proc/stat. We don't create a new /proc file when adding to it. The
original structure is still intact here.
We really need to get a parsing library out to the public. That would
avoid all these issues as the TRACE_EVENT() was originally designed to.

-- Steve





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