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. Yuyang -----Original Message----- From: Steven Rostedt [mailto:rostedt@xxxxxxxxxxx] Sent: Thursday, September 12, 2013 10:01 PM To: John Kacur Cc: Du, Yuyang; linux-trace-users@xxxxxxxxxxxxxxx Subject: Re: Query: is it possible to trace at exactly start and end time of tracing Top posting now, are we? On Thu, 12 Sep 2013 13:40:38 +0200 John Kacur <jkacur@xxxxxxxxxx> wrote: > and when I say, I don't know whether that makes sense or not, it's > because I don't know whether all the snapshot info is in the trace > anyway. (I need to play with the new snapshot feature first) > > On Thu, Sep 12, 2013 at 1:39 PM, John Kacur <jkacur@xxxxxxxxxx> wrote: > > I don't know whether this makes sense or not, but I believe he is > > asking to have trace_on and snapshot on simultaneously. He wants to > > do a trace, but also have the snapshot information that coincides > > with the start and end of the trace. > > I don't think this makes sense. A snapshot "saves" the current trace buffer with a simple swap. Once the swap happens, you have the start and stop of the trace. Unless he simply wants a write to the buffer when the "tracing_on == 0" happens. -- 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
|