 |
 |
On Thursday, September 01, 2011 11:02:50 am Ed Pozharski wrote: > I am almost sure this has been addressed before, so you can go after me > for insufficient googling. However, > > 1. Is there any *significant* advantage in using 64-bit CCP4 binaries > (primarily speed)? > 2. IIUC, the standard CCP4 download results in 32-bit binaries being > run on a 64-bit system. Works for me (except for the weird iMosflm > issue), but given that 64-bit OS is becoming more and more common, isn't > it time for 64-bit binaries option? The answer, of course, is no if you > answered no to 1 above. The generic answer is that there is no intrinsic speed advantage to running a 64-bit binary rather than a 32-bit binary. In fact it may run slower due to larger pointer sizes and hence poorer cache performance. However, 32-bit binaries cannot access more than 4GB of address space. But the x64 architecture provides more registers and faster instructions than x86. So a 32-bit binary using the x64 instruction set can run faster than a 32-bit binary using only x86 instructions. Therefore you need to choose the right compiler options in order to get the benefit of the faster architecture. I do not know if there are specific CCP4 programs that fall outside of the generic case described above. Ethan -- Ethan A Merritt Biomolecular Structure Center, K-428 Health Sciences Bldg University of Washington, Seattle 98195-7742