Sorry, the terms we use confuse a lot. For example, I defined a trace point, trace_a(state), and used it somewhere to trace the state. So what I want is: (trace on, force a trace_a), normal trace_a's ..., (trace off, force a trace_a) Basically, I think I need a notifier at both start and end. Thanks, Yuyang -----Original Message----- From: Steven Rostedt [mailto:rostedt@xxxxxxxxxxx] Sent: Friday, September 13, 2013 10:13 AM To: Du, Yuyang Cc: John Kacur; linux-trace-users@xxxxxxxxxxxxxxx Subject: Re: Query: is it possible to trace at exactly start and end time of tracing On Fri, 13 Sep 2013 01:40:55 +0000 "Du, Yuyang" <yuyang.du@xxxxxxxxx> wrote: > Thank you. > > It turned out I did not understand snapshot, the new feature. > > Yes, I simply want a write to the buffer when the "tracing" begins and ends. John was right in this respect too. > > I think this makes sense (at least) for some cases. The traced is some states, and the delta of states matter. > I'm still not exactly sure what is needed, but you also have the trace_marker, that lets userspace apps (even "echo") write into the trace buffer. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-trace-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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