So close to the launch I think it's time to do a final estimation on Zen's IPC. It is very hard to pinpoint the IPC of a core that has clear compromises in perf. Vs power (ie. slimmer FP unit) but I will give it a try, one final time.
I already tried to do so in
this post. Long story short, I expected that overall average IPC is going to be ~46% higher than XV. Since then I have changed my estimate and now I expect Zen to be ~48% faster than XV core.
To put this number in perspective,
look at this post from majorD. In his benchmarks Skylake has 1.61x (61%) higher IPC than XV core, both chips tested as dual cores with CMT and SMT disabled, so pure single core IPC comparison. Also I took the numbers that had AVX2 workloads in the average since Zen will be tested the same way.
Thanks to Anandtech we know that SB to IB was 5.8% jump, IB to HSWL was 11.2% jump, HSW to BDW was 3.3% jump and BDW to SKL was 3% jump(DDR4). That makes HSW core 1.52x or 52% faster than XV core.
Overall, the gain from SB core to SKL core is around ~25%. Going back to majord's numbers, SB-level of performance would be 1.61 / 1.25 ~=1.29 or SB core has around 29% higher IPC than XV core with AVX workloads in the mix. IB in turn should have around 36% higher IPC and Haswell 1.36x1.112~=1.52x or 52% higher IPC than XV core.
Going back to Zen estimate, ~48% faster than XV would make it a smidge slower than HSW on average (2-3 % points) and around ~6%/~9% slower than BDW-E/SKL, at the same clock. All of this of course without SMT gains taken into account. Looking at CPUz ST->MT scaling on that 6C/12T ES, I can say that there is no surprise in my mind how 3.4Ghz Ryzen can beat 3.5Ghz BDW-E in Handbrake and Blender while having somewhat lower IPC(I guesstimate 6% lower).
Average SMT gains on post SB cores are in the 23-25% range. Ryzen could very well have ~35% gain from its SMT implementation making up for the pure ST IPC deficit vs BDW and SKL cores. 1.35/1.25=1.08 or 8% more performance from their own version of SMT,and like I said before, just about enough in couple of workloads we have seen thus far (and reinforced by higher-than-intel CPUz MT scaling on R5 12T ES).
This was fun for me but, as always, take it with healthy amount of salt of course