On Tue, 14 Dec 2010 20:49:14 -0800 Matt Thomas <m...@3am-software.com> wrote:
> I have a fairly large but mostly simple patch which changes the stats > collected in > uvmexp for faults, intrs, softs, syscalls, and traps from 32 bit to 64 bits > and > puts them in cpu_data (in cpu_info). This makes more accurate and a little > cheaper > to update on 64bit systems. I like the cleanliness of the changes; A potential issue I see is how heavy this becomes on some 32-bit CPUs i.e. m68k, where I see for instance 1 instruction being replaced by 9 instructions (including registers save/restore) to increment a counter. I'm not sure if in practice this will really affect performance, or if it's worth benchmarking for those architectures, however. If it turned out to be a problem, I could see two possible solutions: an option to disable some stat counters on slow systems (values could simply remain 0 in that case), or a new counter type say, cpustatcount_t and macros defined by the MD code to use 32-bit cpu-specific counters where necessary, getting compiled/exported to userland using 64-bit at statistics request time to avoid compat/userland complications... Thanks, -- Matt
