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Message-ID: <20090417162326.GG8253@elte.hu>
Date: Fri, 17 Apr 2009 18:23:26 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
Cc: Jeremy Fitzhardinge <jeremy@...p.org>,
Steven Rostedt <rostedt@...dmis.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
Subject: Re: [PATCH 1/4] tracing: move __DO_TRACE out of line
* Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca> wrote:
> > > +#define DEFINE_DO_TRACE(name, proto, args) \
> > > + void __do_trace_##name(struct tracepoint *tp, TP_PROTO(proto)) \
> > > + { \
> >
> > that needs to be marked notrace, otherwise the function tracer
> > becomes noisy. (or even lockupy.)
>
> I guess I'll have to put it more clearly : I am all for minimizing
> tracepoint header dependency, but I'll be nacking this kind of
> out-of-lining patch. Taking a function call, and moving it
> out-of-line (thus duplicating the function call for nothing) seems
> *really* pointless and will hurt tracer performance.
No need to nak - just say you dont like it and it gets fixed :)
I meant to suggest to Jeremy to measure the effect of this
out-of-lining, in terms of instruction count in the hotpath.
> If thread_info.h is now so big that it needs a cleanup, I guess
> we'll just have to do it.
Music to my ears ...
Ingo
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