On Mon, Nov 17, 2003 at 02:04:26PM -0800, Jeffrey Baitis wrote: > I'm currently trying to increase performance on our PMC-Sierra RM5231 > system by taking advantage of the MIPS IV ISA. This processor has a > 32-bit address bus interface with 64-bit GPRs, so I guess that the > choice of -mabi=n32 is ideal for this processor. In addition to what Daniel just said ... N32 requires a 64-bit kernel to run on which is significantly larger thereby causing more cache misses so a 64-bit kernel is often slower. On the kernel side a 64-bit kernel is drastically better at handling large amounts of memory, so once a 32-bit kernel needs highmem the 64-bit kernel will win the race. Often these effects influence performance more than what you might gain from exploiting a new ISA. Ralf
