Messages in this thread | | | Date | Thu, 6 Nov 2008 13:13:48 -0800 | From | Arjan van de Ven <> | Subject | Re: [PATCH] ftrace: add an fsync tracer |
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On Thu, 06 Nov 2008 15:19:48 -0500 fche@redhat.com (Frank Ch. Eigler) wrote:
> Arjan van de Ven <arjan@infradead.org> writes: > > > [...] > > what is the real need is > > 1) Have a trace point in the source > > 2) Associate a "formatting function" with that point > > (which basically transforms the trace parameters to, say, a > > string) 3) A way to turn the trace point on/off. > > For 1 and 2, it may be worth considering a plain trace_mark() in > do_sync(). The complication that makes this uglier than a one-liner
no why is that?
what you really need is to be able to provide a callback function pointer that will do the formatting, or as Peter wants it, a format string.
(and we can easily make a format string that knows how to print a struct file, no big deal, I suspect that is a common thing actually)
Doing this like you propose is just too complex and too specialistic; the reality is that merely formatting the arguments of a trace point is the common case, and I suspect for 99.9% of the cases we can get away with a standard default formatting.
We should make THAT easy. Not complex or ugly. But easy.
And then if I or some tool wants to see a tracepoint, we have some standard way to enumerate them and turn individual ones on with their standard formatting ... and that's it. no iffs or buts
-- Arjan van de Ven Intel Open Source Technology Centre For development, discussion and tips for power savings, visit http://www.lesswatts.org
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