Informal results of moving from 32-bit Ubuntu 12.04 to 64-bit Ubuntu 12.10.

I was only interested in floating point performance for the suite of unit tests for this code:

http://code.google.com/p/pyeq2/downloads/list

when runfrom a command line and had no interest in other results. I was hoping for performance improvements both from the Ubuntu changes to the numerical libraries I use, numpy and scipy, and improved virtual CPU performance due to 64-bit matrix vectorization.

The test suite repeatedly runs in 3/4 of the previous minimum total elapsed time.

I made sure to run the test suite repeatedly on different days and look for the minimum time, rebooting into different 32/64 bit disk images and re-rerunning the test suite. The results were sufficiently convincing for me to make the switch.

James

I switched my desktop to 64 bit Ubuntu a couple of years ago after running 32 bit for years. This machine is 7.5 years old. I don't run scientific apps and haven't really noticed much overall improvement. Minecraft on 64 bit runs better I think. In general my system has less free memory than when it was 32 bit. Rather, it freed up some upper memory that isn't addressable on 32 bit but overall apps seem to use more memory. Or maybe it's just the newer Ubuntu versions, particularly Unity.

There are definitely performance advantages for a few specific cases. 64-bit isn't worth it for most Linodes, especially since they're not typically CPU-bound (so the extra overhead in RAM usage doesn't serve any purpose), but for some specific things it can make sense. To be honest, I'm not surprised that you of all people would be the one to fit that specific case, since you're one of the very few Linode customers that are completely CPU-bound