Messages in this thread | | | Subject | Re: [ANNOUNCE] New utility: 'trace' | From | Peter Zijlstra <> | Date | Wed, 17 Nov 2010 14:02:37 +0100 |
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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?!
As to the trace_printk() to perf interface, you could do like mingo did and create a fake event and use the regular tracepoint interface, or hook it up directly and create a PERF_RECORD_TEXT field.
Personally I like the trace_printk() as a TRACE_EVENT(printk), it also allows removing lots of the special casing concerning trace_printk from ftrace.
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