I myself recently had the misfortune of trying to get a java program
relying on the (apparently 32-bit only) "JMF" package to run on 64-bit
linux. This wasted almost an entire week of my life! I tried
downgrading the operating system to 32-bit, but that reduced the number
of "CPUs" available in the system from 24 to 8. Still don't know why
that is (I'm not all that familiar with Ubuntu, and don't want to be),
but I imagine one could call that a "performance hit".
On the whole, however, I have not seen any significant performance
advantage of 64 over 32 bit running crystallography programs
side-by-side on equivalent hardware. I have also been unimpressed with
the supposed "memory access" advantages of 64 bit. I had to do a LOT of
recompiling programs in order to create maps or MTZ files bigger than 2
GB, and I also still have certain programs "running out of virtual
memory" at 4GB as well. Despite the fact that the relevant machine has
48 GB of RAM and 80 GB of swap.
I tell you. Technology just doesn't work.
-James Holton
MAD Scientist
On 4/4/2012 2:21 AM, Takanori Nakane wrote:
Dear Tim,
64-bit is about memory addressing - why would you expect a performance
boost? I have wondered where this notion originated from.
The x86_64 architecture has more registers than 32bit (x86)
architecture. Register access is faster than memory access so
the more data programs can put on registers, the faster it runs.
Best regards,
Takanori Nakane
