Performance difference b/w 32bit and 64bit

[avanwz]

First thanks to everyone who has interesting in my previous questions.

Now, I'm ready to run my program, and my code is based on 32bit version.

So I run the program on Ubuntu 9.10 32bit. And I got running time for 48s.

But that's a bit slower than I expected; the program has bunch of File I/O

processing but the result(48s) just doesn't make sense compared to given initial

data set. So I just run the same program and same initial data set on Ubuntu 9.10

64bit ver. Then, bang!! it took 1.4s to finish the job.

Do you have any thoughts what kind of fact might make this significant difference?

The differences b/w those two OS are "32 vs 64" and 32bit version has Java SDK,

Eclipse, Apache2, Mysql, PHP, CGI, and python. We-server service is running but

because I'm not really running web server.

Did the result come from these background programs?

What do you think?

-- I tested it on the both OS in the same situation as possible as I can.
(reboot->test)

-- Oh, BTW 64bit one doesn't have those programs. I just installed on my external hard drive, so it's literary PURE one. (32bit one also in the same HDD)

-- I run these Ubuntus on VMware

[GNU-Fan]

If you run these tests in VMWare, and the host is 64Bit, it make sense to me that 32Bit runs slower. I assume the 32Bit mode must be emulated while the instructions in 64bit can be executed by the host processor directly.

[avanwz]

Well, the thing is that the host OS is Win7 32bit ver.

So 64bit Ubuntu must be emulated but it's much faster!!!

[GNU-Fan]

Yes, strange.