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Java Forum / General / April 2006java vs c++ speed benchmarks
Anyone now where i can find some recent java vs c++ speed benchmark? possibly for scientific computation? possibly with the source code? Thanks Dimitri > Anyone now where i can find some recent java vs c++ speed benchmark? > possibly for scientific computation? possibly with the source code? Ah, lies, damn lies... And benchmarks! The ultimate troll/zealot argument... Where of course everybody pretends to be unbiased. :) One such flawed comparison can be found here: "The Java is Faster than C++ and C++ Sucks Unbiased Benchmark" http://www.kano.net/javabench/ See how the author says that "C++ Sucks" and "Unbiased Benchmark" in the same sentence? (that's pretty much trolling in my book ;) And then some "unbiased rebuttal" here : "The 'Java Faster than C++' Benchmark Revisited" http://www.freewebs.com/godaves/javabench_revisited/ They do the usual Sieve, Ackerman, Matrix, etc. using different setup and compare them. For what it's worth. I consider such articles to be "zealotry approaching trolling" and I post these just to show how easy it is to "fake" benchmarks and to make them so your pet language looks like the "winner". :-/ The most serious comparison I've seen so far seems to be the following one: http://shootout.alioth.debian.org/ Choose an architecture, choose an algorithm and compare results. All source code are available. I think this may be what you're looking for :) Is it for a massively distributed scientific computation (like SETI@Home) ? For something running on one of the planet's Top500 supercomputer ? For some product running client-side to be installed on many clients ? For if it's not, I'd argue that the money saved by reducing development time could probably be used to buy faster hardware... That said YMMV and all that, Alex thanks Alex, I've seen that the difference between java and c++ is from 1.2-2 times faster for c++.. thanks.. so I've matrix of about 10.000 x 10.000 elements... so.. perhaps i'll go back to C++ for the math.. thanks > thanks Alex, > I've seen that the difference between java and c++ is from 1.2-2 times > faster for c++.. thanks.. That is way too simple a statement to be true, or even useful. Computationally, Java is often maybe 5 to 10% slower than C++ on average, assuming that code has been optimized (i.e., is not running for the first or second time this app instance). Other factors, like the memory model and garbage collection, play a huge role in typical performance numbers. A large matrix calculation is unlikely to suffer many such problems. On the other hand, passing a matrix that large to native code, even through JNI, may be rather slow depending on the VM. I'd actually encourage you to work on this one in Java.  Signaturewww.designacourse.com The Easiest Way To Train Anyone... Anywhere. Chris Smith - Lead Software Developer/Technical Trainer MindIQ Corporation I've not only matrix product but i must use other operation such as exponential on some combination of the matrix components. Exponential in c++, using somthing like mkl (wich uses cpu optimized assembly) or inline assmbly can be from 4 to five times faster.. so if for matrix product, and usal loop the optimization done by jit can be very good for this kind of thing, where a java method can be substitued by and asm isntruction, no kind of jit can do anything, it can't recognize an assembly op from an high level implementation... And you are right.. to pass so much data from java to c++ using jni is not fast... can I use java only to show the results at a given time? Thanks Dimitri > I've not only matrix product but i must use other operation such as > exponential on some combination of the matrix components. Exponential [quoted text clipped - 4 lines] > asm isntruction, no kind of jit can do anything, it can't recognize an > assembly op from an high level implementation... I didn't really understand a word of that; but if you already know that C++ code is running 4 to 5 times faster than Java for your application, then why did you post here asking for benchmarks? You should have instead posted your code asking for help with optimizations. You must be doing something wrong in the Java version, if you're getting that kind of a performance difference. Signaturewww.designacourse.com The Easiest Way To Train Anyone... Anywhere. Chris Smith - Lead Software Developer/Technical Trainer MindIQ Corporation I'm sorry for my english and for the lack of.. coherence? in the previews post and I'm not sure of nothing.. my problem is how much difficult should be rewriting all my code in c++ or using jni, and if doing so will be usefull and productive. In any way for some function like exponential it is not important how much the jit is powerful becouse the code is wrong.. it must use one only asm instruction and it can't if the jvm doesnt support it.. the only information about it that i've found are: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=5005861 >Submitted On 12-JAN-2006 >This is the last area that Java appears slow compared to c/c++ - it really MUST be >fixed. It's nice that Tan, LN and Log10 have been intrinsified in Mustang, but it's sin, >cos and sqrt that most people really need, I think. If you have better info, i'll be very interested in them. Thanks Dimitri > http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=5005861 > >Submitted On 12-JAN-2006 > >> This is the last area that Java appears slow compared to c/c++ - it really MUST be >fixed. It's nice that Tan, LN and Log10 have been intrinsified in Mustang, but it's sin, >cos and sqrt that most people really need, I think. > > If you have better info, i'll be very interested in them. http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=5094249 Bug ID: 5094249 Votes 0 Synopsis TAN needs to be implemented for X86/AND64 Category hotspot:compiler2 Reported Against mustang Release Fixed mustang State Closed, fixed Related Bugs Submit Date 30-AUG-2004 Description SIN/COS are intrinsified for X86/AMD64, we should support TAN as well. Work Around N/A Evaluation easy xxxxx@xxxxx 2004-09-01 Implemented this for C1 as well as C2 xxxxx@xxxxx 2004-09-07 Of course, this sort of stuff is highly implementation dependent. You also need to consider whether you are prepared to bet on mustang having sufficient quality for your needs. Tom Hawtin SignatureUnemployed English Java programmer http://jroller.com/page/tackline/ Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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