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by dragontamer 2749 days ago
> Do you have a reference?

Yes and no. Apparently, my mind messed up my memory. So it was a leaked post on /r/intel. I thought it was for 9000-series, but apparently it was a leak for Cannon-Lake. So I was mistaken.

Second: the post has since been deleted. You can see the claims in the comments still however.

https://old.reddit.com/r/intel/comments/9ol9is/instruction_t...

> FWIW, even for Skylake, Agner reports 26 cycles for a 32-bit idiv, so the chip is already close (if you were talking 32-bit division).

The post used to alleged 20ish cycles for 64-bit division (!!). So I guess that's something to look forward to testing.

1 comments

I just ran some tests on CNL and indeed the behavior is very different than earlier chips. I am seeing ~15 cycle divs with no pipelining (i.e,. the latency and inverse throughput are both 15), versus 36+ cycles latency and 25+ cycles inv throughput on Skylake.

Interesting. I found only a few other changes beyond that, so far.

CNL also added another AES unit, so you can now dispatch aesenc and its ilk to ports 0 and 1.