ni...@lysator.liu.se (Niels Möller) writes: paul zimmermann <paul.zimmerm...@inria.fr> writes:
> page 1: the division instruction is now much faster than before on modern > processors According to https://gmplib.org/~tege/x86-timing.pdf, they're still an order of magnitute slower than multiplication. E.g 86 vs 3 cycles on Intel skylake. And in addition, multiplication is piplined, division likely isn't. Last time I explored this, the division instructions (div/idiv) ran at varying speed as long as the upper dividend word is zero. When it is, the timing is rougly linear in either log2(dividend) or log2(quotient). But the fastst time is still some 10 cycles, IIRC. And as Nisse says, it is not pipelined. The relative throughput between mul and div can still be on the order of 10x in the best case and 100x in the worst case. -- Torbjörn Please encrypt, key id 0xC8601622 _______________________________________________ gmp-devel mailing list gmp-devel@gmplib.org https://gmplib.org/mailman/listinfo/gmp-devel
