4 ms·
This is misleading, at least if you're looking at a single core. A single core can have >100 instructions in flight, but most of them will be waiting for their
by atq2119 7y ago
This is misleading, at least if you're looking at a single core.
A single core can have >100 instructions in flight, but most of them will be waiting for their operands to arrive. The theoretical maximum throughput is gated by the instruction decoders and execution units, and is an order of magnitude lower.
- nickysielicki 7y agoThat's fair to call me out on that, what I said wasn't clear. I think the broader point still stands though: don't look at the number of ISA instructions and think that fewer instructions necessarily means performance improves. I think that we also miss a piece of the puzzle in terms of what happens once you leave ISA instructions and get into uops. There's magic inside there and it's completely opaque.