Messages in this thread | | | Date | Sat, 27 Sep 2008 20:42:12 +0200 | From | Ingo Molnar <> | Subject | Re: [RFC PATCH 1/3] Unified trace buffer |
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* Steven Rostedt <rostedt@goodmis.org> wrote:
> > On Sat, 27 Sep 2008, Ingo Molnar wrote: > > > > If all you do is to trace high-freq events on all CPUs and you are _not_ > > interested in the precise interactions, the overhead of global > > synchronization can hurt a lot. > > > > In any case, SMP coherency of trace events is an independent property of > > the tracer, and preferably something that can be turned on/off. > > Just a note. The current ring buffering system that I'm proposing > keeps its own time stamp counter (currently sched_clock) that will > most likely be updated later. I'm trying to keep this ring buffer > system as dumb as possible. It does not even implement the merge sort. > That's up to the tracer to handle. There's nothing stopping the trace > from adding some atomic counter to each event to help it sort.
correct. The price is all the notifier/callback overhead and the loss of type checking of the record contents. But that's an unavoidable price of abstraction, at least in C.
> So yes, the tracer can implement anything it wants on top of the ring > buffer ;-)
yes, very nice! :)
Ingo
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