Messages in this thread | | | Date | Thu, 16 Dec 2010 14:36:35 -0500 | From | Jason Baron <> | Subject | Re: [PATCH/RFC 1/2] jump label: make enable/disable o(1) |
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On Thu, Dec 16, 2010 at 08:33:51PM +0100, Peter Zijlstra wrote: > On Thu, 2010-12-16 at 14:23 -0500, Jason Baron wrote: > > > > For the jump label disabled case, perf is using atomic_inc/dec and atomic_read > > to check if enabled. While other consumers (tracepoints) are just using an > > 'int'. I didn't want hurt the jump label disabled case for tracepoints. > > If we can agree to use atomic ops for tracepoints, or drop atomics from > > perf, that would simplify things. > > I had a quick look at the tracepoint stuff but got lost, but surely it > has a reference count somewhere as well, it needs to know when the last > probe goes away.. or does it check if the list is empty? > > Anyway, tracepoint enable/disable isn't a real fast-path, surely it > could suffer an atomic op?
It is the atomic_read() at the tracepoint site that I am concerned about.
thanks,
-Jason
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