On Thursday 01 February 2007 15:29, Jiri Bohac wrote: > If I do: > rdtscll(a) > ... > rdtscll(b) > is it guaranteed that (b > a) ?
It's not architecturally -- unless you have a barrier. On P4 the micro architecture guarantees it, but there the barrier in get_cycles_sync is patched away. On other x86-64s it is generally needed. The effect can be also seen between CPUs. > Because of the __vxtime.cpu[cpu].tsc_invalid flag. We may be You can still precompute it for the HPET etc. case. They are already slow, but saving a condition there might be still worth it. -Andi - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/