0 ms, does that make it infinity times faster? Sounds about right to me! ;-)
On Wed, Jan 13, 2010 at 3:48 PM, Stuart McCulloch <[email protected]> wrote: > 2010/1/13 HommeDeJava <[email protected]> >> >> Greetings folks, >> >> I came across this pretty strange testbed which compares Java and C++ >> performance on <a href="http://www.developer.com/java/article.php/ >> 3856906/Java-vs-C-The-Performance-Showdown.htm"> Gamelan.com</a> and >> promoted by a Java/Open Source Daily newsletter, from Gamelan which I >> supposed should promotes Java and Open Source despite a lot of >> Microsoft ads ;-) >> >> The testbed claims to show that C++ is 25,000 times faster than Java. >> From what I know about the JVM, I was expecting C++ to be at most 5 to >> 10 times faster. >> Am I wrong? >> >> Maybe the C++ compiler/optimizer had removed dead code from the >> testbed. >> Furthermore, in order to perform as fast as stated, the computer >> should run over 20 Ghz ??? >> >> Furthermore, some readers have carefully observed, in order to ensure >> such a performance, the computer should run at over 20 GHz. >> >> What do you think about this so-called testbed? > > there's a fatal flaw in the test - the compute method doesn't return > the result of the computation, alter any of the arguments, or have > any side-effects - which means to the rest of.the program it can > be safely considered as a no-op > > the C compiler (with optimization) realizes this and removes the > method call, which explains the crazy fast times as it's not really > doing anything except the timing calls > > the HotSpot client JVM (and JIT) doesn't detect this which is why > it appears much slower, because it's actually doing the calculation > > however if you turn on escape analysis (is this still in the 6.0 builds?) > or use the IBM 6.0 JVM which comes with escape analysis enabled > then you get results that are more in line with C: > > Java computing took 4 (ms) > > and if you run the compute method enough times beforehand so the > JIT optimizes it (a few thousand times should do it) then you get even > better results: > > Java computing took 0 (ms) > > HTH :) > >> Are there any good benchmarks comparing C and Java? >> >> Thanks > > -- > Cheers, Stuart > > -- > You received this message because you are subscribed to the Google Groups > "The Java Posse" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/javaposse?hl=en. > >
-- You received this message because you are subscribed to the Google Groups "The Java Posse" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/javaposse?hl=en.
