Messages in this thread | | | Date | Wed, 17 Nov 2010 14:10:23 +0100 | From | Ingo Molnar <> | Subject | Re: [ANNOUNCE] New utility: 'trace' |
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* Peter Zijlstra <peterz@infradead.org> wrote:
> On Wed, 2010-11-17 at 13:53 +0100, Frederic Weisbecker wrote: > > On Wed, Nov 17, 2010 at 12:35:50PM +0100, Peter Zijlstra wrote: > > > On Wed, 2010-11-17 at 09:30 +0100, Ingo Molnar wrote: > > > > > For example I'm currently working with dozens of trace_printk() and I would be > > > > > very happy to turn some of them off half of the time. > > > > > > > > I guess we could try such a patch. If you send a prototype i'd be interested in > > > > testing it out. > > > > > > I don't see the point, the kernel shouldn't contain any trace_printk()s > > > to begin with.. > > > > > > It's oriented toward developers. Those who use dozens of tracepoints in > > their tree because they are debugging something or developing a new feature, > > they might to deactivate/reactivate some of these independant points. > > > > This can also apply to dynamic_printk of course. > > > > Well, the very first and main point is to standardize trace_printk into > > a trace event so that it gets usable by perf tools. I have been asked many > > times "how to use trace_printk() with perf?". > > Thing is, since its these dev who add the trace_printk()s to begin with, I don't > see the point in splitting them out, if you didn't want them why did you add them > to begin with?!
That's a common workflow: lots of printks (trace_printk's) put all around the code - and sometimes one set of tracepoints is needed, one time another set.
_If_ we succeed in presenting them like Frederic suggested it, and if we make the turning on/off _simpler_ (no kernel modification) and faster (no kernel reboot) via the tooling, people like Frederic might start using it.
I dont think we should fight the workflow itself - it makes sense.
The only question is whether we can represent it all in a nicer fashion than 'modify the source code and reboot'. If we cannot then there's no point - but i'm not sure about it and Frederic seems to be convinced too that he can make such a switch on/off facility intuitive. We'll only see if we try it.
Also, i dont see any harm - do you?
Thanks,
Ingo
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