Re: [GIT PULL] tracing: make signal tracepoints more useful

From: Steven Rostedt
Date: Mon Jan 16 2012 - 07:31:12 EST


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



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/