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Hi everyone!
I wanna speed up the program I am creating now. I heard one way to do
it is to use JIT. Is it possible to enable it on HotSpot VM? If it is
how can I do that?
Thanks in advance.

Dmitriy Melnik wrote on 21.02.2009 18:47:
> Hi everyone!
> I wanna speed up the program I am creating now. I heard one way to do
> it is to use JIT. Is it possible to enable it on HotSpot VM? If it is
> how can I do that?

It's enabled by default, there is nothing you need to do.

You can only influence the threshold when bytecode gets compiled into native
code (after how many executions)

For details see:

http://java.sun.com/javase/technolog.../vmoptions.jsp

Thomas Kellerer wrote:
> Dmitriy Melnik wrote on 21.02.2009 18:47:
>> Hi everyone!
>> I wanna speed up the program I am creating now. I heard one way to do
>> it is to use JIT. Is it possible to enable it on HotSpot VM? If it is
>> how can I do that?
>
> It's enabled by default, there is nothing you need to do.

Not only is id enabled by default - I don't even think it can
be disabled in newer JVM's.

Arne

On 21 ÆÅ×, 21:03, Thomas Kellerer <FJIFALSDG...@spammotel.com> wrote:
> Dmitriy Melnik wrote on 21.02.2009 18:47:
>
> > Hi everyone!
> > I wanna speed up the program I am creating now. I heard one way to do
> > it is to use JIT. Is it possible to enable it on HotSpot VM? If it is
> > how can I do that?
>
> It's enabled by default, there is nothing you need to do.
>
> You can only influence the threshold when bytecode gets compiled into native
> code (after how many executions)
>
> For details see:
>
> http://java.sun.com/javase/technolog.../vmoptions.jsp

Thanks a lot!

So another question arouse. What VM can provide the best performance?
The matter is I am creating a cryptographic system and need it run as
fast as possible.

Dmitriy Melnik wrote:
> So another question arouse. What VM can provide the best performance?
> The matter is I am creating a cryptographic system and need it run as
> fast as possible.

I don't think the difference is that big. For newer Java versions SUN's
with -server is approx. as fast as IBM's and BEA's.

If you test with your specific code, then one of them may
be a bit faster than the other, but you may find a different
one to be faster with some other code.

Arne

On 22 ¬æ¬Ö¬Ó, 01:38, Arne Vajh©ªj <a...@vajhoej.dk> wrote:
>
> I don't think the difference is that big. For newer Java versions SUN's
> with -server is approx. as fast as IBM's and BEA's.
>
> If you test with your specific code, then one of them may
> be a bit faster than the other, but you may find a different
> one to be faster with some other code.
>
> Arne

Thanks! I really appreciate your help.

Dmitriy Melnik wrote:
>>> So another question arouse. What VM can provide the best performance?
>>> The matter is I am creating a cryptographic system and need it run as
>>> fast as possible.

Arne Vajhøj wrote:
>> I don't think the difference is that big. For newer Java versions SUN's
>> with -server is approx. as fast as IBM's and BEA's.
>>
>> If you test with your specific code, then one of them may
>> be a bit faster than the other, but you may find a different
>> one to be faster with some other code.

Dmitriy Melnik wrote:
> Thanks! I really appreciate your help.

Two approaches to increase speed:
- tune the VM parameters (-server, -X and -XX options);
- throw hardware at the problem.

If your application is correctly multithreaded, then additional CPU cores can
speed things up (subject to Amdahl's Law). More memory can help to a point,
especially on 64-bit platforms. If I/O is an issue in your application,
faster disks will help. No optimization of a slow algorithm will improve
things as much as a faster algorithm, assuming equivalent correctness.

The dictum for optimization is to measure performance first, then again after
optimization attempts. Results are often counter-intuitive.

--
Lew
Please trim sigs.

Lew wrote:
> Dmitriy Melnik wrote:
> >>> So another question arouse. What VM can provide the best performance?
> >>> The matter is I am creating a cryptographic system and need it run as
> >>> fast as possible.
> Arne Vajhøj wrote:
> >> I don't think the difference is that big. For newer Java versions SUN's
> >> with -server is approx. as fast as IBM's and BEA's.
>
> >> If you test with your specific code, then one of them may
> >> be a bit faster than the other, but you may find a different
> >> one to be faster with some other code.
> Dmitriy Melnik wrote:
> > Thanks! I really appreciate your help.
>
> Two approaches to increase speed:
> - tune the VM parameters (-server, -X and -XX options);
> - throw hardware at the problem.
>
> If your application is correctly multithreaded, then additional CPU cores can
> speed things up (subject to Amdahl's Law). *More memory can help to a point,
> especially on 64-bit platforms. *If I/O is an issue in your application,
> faster disks will help. *No optimization of a slow algorithm will improve
> things as much as a faster algorithm, assuming equivalent correctness.
>
> The dictum for optimization is to measure performance first, then again after
> optimization attempts. *Results are often counter-intuitive.
>
> --
> Lew
> Please trim sigs.

Thanks for the useful post. I've already played with VM options a
little bit. Quadratic sieve factoring algorithm runs about 10% faster
with the combination of -server and -XX:+AggressiveOpts options.

Btw, what do you mean by trimming sigs? I'm a complete newbie on
Usenet.

Arne Vajhøj wrote on 21.02.2009 19:15:
> Thomas Kellerer wrote:
>> Dmitriy Melnik wrote on 21.02.2009 18:47:
>>> Hi everyone!
>>> I wanna speed up the program I am creating now. I heard one way to do
>>> it is to use JIT. Is it possible to enable it on HotSpot VM? If it is
>>> how can I do that?
>>
>> It's enabled by default, there is nothing you need to do.
>
> Not only is id enabled by default - I don't even think it can
> be disabled in newer JVM's.

Yes you can: -Xint

http://java.sun.com/javase/6/docs/te...dows/java.html