Hi, On 12/8/23 04:27, Luca wrote: > How much faster is this? did you measure also on hw? I would use RDTSC > to do it, I don't know if there are better ways. So, ~8 microseconds was reduced to ~60 nanoseconds, so roughly 100 times faster. I don't know how to do it with rdtsc.
> Interestingly, Linux uses either LSL or RDPID to obtain the same value, > I wonder if they could be an easy alternative. No idea about these. > Also, could it be that there is a particular use of it that is much more > frequent than the others, and that might benefit from further optimizations? Perhaps, but it still makes sense not to use LAPIC mmio registers when a cpuid instruction exists. Damien
