32-bit vs. 64-bit Ubuntu 13.04 Linux Performance

[kobblestown]

Any ideas why the big difference in some cases? I was hoping they were more or less equal, maybe with the 64 to have an edge.

In 64-bit mode the processor has twice the number of registers. So more data can be kept there. Also, the calling convention uses more registers to pass values - no need to put them on the stack for most functions. Also, the FPU implements SSE2. Sure, you can use SSE2 in 32-bit code but your code has to check for the presence of SSE2 because that's not guaranteed. So I assume most application on 32-bit land are compiled with x87 FP code which is slower. I think there's faster SYSCALL instruction too. Maybe other things as well.

The major drawback is that pointers are twice the size so for pointer heavy applications it might get a bit slower. But it seems that overall 64-bit is worth it. I've been using 64-bit Ubuntu for 5 years now. Never had any problems. And all 32-bit applications run fine. Initially I ran them in a 32-bit jail but now I don't bother. Properly made 32-bit packages for 64-bit distributions pull in the 32-bit libs so it's fine. The dynamic linker knows what libs are needed and where to find them.

[curaga]

More than just the OA text doesn't match the graphs. Michael, don't write while tired :P

[Mike Frett]

32Bit

I confess, I use 32Bit Xubuntu. I use it for compatibility and because I have only 4GB Ram. I also use it because, at the time I got the ISO, the page actually recommended I use the 32Bit version. There are still people having issues with 64bit believe it or not and a lot of software only has 32bit versions. I can say with confidence, I'll be using 32bit for the foreseeable future. At least until I get 8 or 16 GB of Ram, then I'll move to 64Bit. But right now I have zero use for it, 32Bit is working out fine for me. I understand I may sound odd to some of you, but it's working out great for me.

[startzz]

Well, again, its only better for ancient intel graphics, the story would be completely different with at least ivy bridge, or even better - with a real graphics card with real CLOSED source drivers

[vcunat]

OpenArena

Am I missing something or is your comment on the OpenArena tests on the second page innaccurate?

Yes, that's exactly what I wanted to point out (independently). For OpenArena 32-bits seem certainly better (from the graphs), not the other way.

It also might be interesting how x32 compares (not in Ubuntu ATM). http://www.phoronix.com/scan.php?pag...tem&px=MTEwMTk

[bawkbawkboo1]

Am I missing something or is your comment on the OpenArena tests on the second page innaccurate?

[phoronix]

Phoronix: 32-bit vs. 64-bit Ubuntu 13.04 Linux Performance

While nearly all modern Intel/AMD x86 hardware is 64-bit capable, among novice Linux users the question commonly is whether to install the 32-bit or 64-bit version of a given distribution. We have previously delivered benchmarks showing Ubuntu 32-bit vs. 64-bit performance while in this article is an updated look in seeing how the 32-bit versus 64-bit binary performance compares when running Ubuntu 13.04 with the Linux 3.8 kernel.

http://www.phoronix.com/vr.php?view=18676