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Re: static user probe performance
On Wed, 2010-04-07 at 10:43 -0400, Frank Ch. Eigler wrote:
> >> run with stap
> >> [...]
> >> elapsed time
> >> volatile semaphore 1858.71
> >> no volatile no semaphore 1865.68
> >> volatile no semaphore 1873.07
> >> no volatile semaphore 1878.09
> >
> > So for this particular microbenchmark, systemtap probing imposes a 30x
> > slowdown, yikes. How many probe hits does this represent?
>
> From scox's later numbers, that's 192 million hits, for about 9
> us/hit, which seems rather high.
Yes, it is high. Are you probing a multithreaded app? We have a known
performance problem there:
http://sourceware.org/bugzilla/show_bug.cgi?id=5660
Jim