3 ms·
... no. And your mental model of what operations cost is a little out of whack. On the newest Intel cpus, a vector double precision multiply is 4 cycles. A hor
by Tuna-Fish 5y ago
... no. And your mental model of what operations cost is a little out of whack.
On the newest Intel cpus, a vector double precision multiply is 4 cycles. A horizontal add is 6 cycles. There is a single instruction dot product, which is 9 cycles.
Something like a dot product for fp can only ever be 1 cycle in a cpu that has a very low clockspeed. (Or is a barrel processor or something.) There is simply too much to do.
- dnautics 5y agoSorry I should have been precise and said dispatch able one per clock cycle, not latency one clock cycle. Amortized over pipelined operations with no dependencies, the net cost of such an operation is one clock cycle. Anyways I checked it, it's DPPS, and it is a 25 clock cycle latency operation, with a throughput that yields an amortized 6 clock cycle cost.