On 02/22/2013 12:19 PM, Michael Wang wrote: > >> > Why not seek other way to change O(n^2) to O(n)? >> > >> > Access 2G memory is unbelievable performance cost. > Not access 2G memory, but (2G / 16K) memory, the sbm size is O(N). > > And please notice that on 16k cpus system, topology will be deep if NUMA > enabled (O(log N) as Peter said), and that's really a good stage for > this idea to perform on, we could save lot's of recursed 'for' cycles. >
CPU execute part is very very fast compare to the memory access, the 'for' cycles cost is most on the memory access for many domain/groups data, not instruction execution. In a hot patch, several KB memory access will cause clear cpu cache pollution then make kernel slowly. -- Thanks Alex -- 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/
