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. On Thu, Sep 12, 2013 at 1:09 PM, Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > On Thu, 12 Sep 2013 04:58:41 +0000 > "Du, Yuyang" <yuyang.du@xxxxxxxxx> wrote: > >> Thanks, Steve. >> >> Virtually, what I want is: >> >> tracing_on(1), snapshort, traces..., snapshot, tracing_on(0). >> >> If I understand right, I need the new feature "snapshot" in ftrace. But, it seems snapshot and ftrace are separated, which does not satisfy my need. >> > > I don't understand what you mean by "snapshot and ftrace are > separated"? The snapshot feature is part of ftrace. Basically, you have > two buffers: an active one, and a static one. When you echo 1 into the > snapshot file, it swaps the two buffers. The active one becomes the > static one, and the static one becomes the active one. > > This allows you to save off a trace while tracing continues. > > -- 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 -- 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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