Comment by O_H_E | Hacker News Reader

Comment by O_H_E | Hacker News Reader

Parent Full thread

If you are asking a general question about single threaded performance, then YES. Modern CPU performance is about so much more than clock speeds, and the TLDR is that there are many non-orthogonal factors that sometimes the only trustworthy quantifier is workload benchmarking.

If you're asking whether that 5Ghz is different than this 5Ghz, the main easy answer IPC (instructions per clock). Unfortunately there are no official IPC numbers, but every new release comes with vague unlabeled slides showing %increase, and then reviewres do their pinning the CPU at a specific clock and measure single-threaded performance to estimate relative IPC improvements (like this https://www.guru3d.com/articles-pages/core-i9-12900k-review,...)

If we go into multi-threaded workloads like compilation, then of course the new one completely throws the 8700k out of the water.

But please don't feel pressured to get on the latest and greatest bandwagon, I'm right here running around with a Thinkpad T460s (with a little bit of a need to upgrade).

_Usually_, if you are not waiting for your computer while CPU is on +90% utilization, there should be little gained from a CPU upgrade. (Workloads that depend heavily on cache size or memory latency are counter-examples)

"Unfortunately there are no official IPC numbers"

Nor can there really be. IPC varies pretty wildly, and depends a LOT on optimization for a particular CPU architecture. The instruction mix should match the CPU model's execution units in addition to not having any dependency stalls.

I once compiled a list of architectures’ relative IPC on the SPECINT 2006 benchmark:

  Cortex-A73 (ARMv8-A)  64.4
  Pentium M   69.0
  Bulldozer (AMD FX)  76.2
  K10 (Phenom II)   76.7
  Goldmont Plus (Atom 2nd gen) 77.5
  Core    80.0
  Bobcat    81.3
  Nehalem    90.0
  Jaguar (PS4)   93.5
  Sandy Bridge  100.0
  Tremont (Atom 3rd gen) 100.7
  Ivy Bridge  105.8
  Cortex-A76 (ARMv8.2-A) 114.7
  Zen   115.9
  Haswell   117.6
  Zen+   119.3
  Broadwell  121.5
  Skylake   124.0
  Zen 2   139.8
  A10 (ARMv8.1-A)  139.8
  Cortex-A77 (ARMv8.2-A) 141.0
  Sunny Cove Ice Lake 146.3
  Cypress Cove Rocket Lake 147.6
  Zen 3   167.4
  A11 (ARMv8.2-A)  186.0
  A12 (ARMv8.3-A)  213.8
  A13 (ARMv8.4-A)  235.0
  A14/M1 (ARMv8.5-A) 236.7

Really highlights the absolutely massive gap between Apple Silicon and Cortex/the-rest-of-ARM. Although you'd really want to classify which Cortex SoCs you're using in that list, as implementers love to chop off the L2 & L3 caches to save die space. This is how we ended up with the bigger.big.little configurations - the "biggest" CPU is just the full CPU with all the caches it was supposed to have had.

Known-(very-)naive question: how and why is the M1 so far beyond both the-rest-of-ARM and both Intel (236.7-(Rocket Lake=147.6)=89.1) and AMD? ((236.7-(Zen 3=163.4)=73.3)?

Of course the technically correct answer I'm not looking for is "because Apple optimized it better" :D, I'm looking more at the (obviously probably extrpolated/guessed) path they took to get there. For example perhaps the increased memory bandwidth contributed (ie $pc go brrrrt :P) but like... this is like the elephant in the room that Apple is basically The Best™ ARM shop in town right now, and I guess I'm trying to reason both about the engineering (how Apple got to where they are now) and the market reaction (how Apple and everyone else are going to go forward).

That IPC figure is a bit misleading because different designs clock differently, for example the Apple designs likely have shorter pipelines which uses cycles and power more efficiently but won't support higher clock speeds. I doubt an M1 could hit 7.8GHz no matter how much cooling you gave it, but the Intel design will never be as energy efficient. Apple has different manufacturing constraints because vertical integration likely lets them spend more on the dies, they are using better fabs, etc. Meanwhile they prioritize having very few variants in a way Intel doesn't (or from another standpoint can't because they need more SKUs to sell). The engineers who do this stuff are living in 100-dimensional tradeoff land though, unlike what popular tech rants tend to imply there are no free lunches.

At a higher level it is just hard to do designs at this complexity so the dominating factor is budget divided by how many different products the team needs to make. Intel is the outlier, they managed to sabotage their own dominant position, but across the rest of the CPU world this holds true.

At very least Apple have the process budget and dollar budget to have really expensive DRAM, huge caches, and huge pipeline/big buffers (big ROB etc.)

It’s described in detail at Anandtech [1][2]. It has mostly to do with the fact that Apple’s chips are so much larger in every way measurable. There’s no magic, just raw performance from comparably massively over engineered designs. At the time of its release their reorder buffer had 630 entries vs Intel’s 352 and AMD’s 256. The floating point units inside the cores could handle quadruple of Intel’s throughput per clock. Etc. Etc.

[1]: https://www.anandtech.com/show/16226/apple-silicon-m1-a14-de...

[2]: https://www.anandtech.com/show/16192/the-iphone-12-review/2

Is this compiled from one source or (say) from individual anandtech bnenchmark results? I just say this to ask if there is repeated readings.

It’s compiled from Anandtech benchmarks and archived forum posts. Unfortunately I didn’t write down each source.

Amazing how much better the M1 is relative to Intel's offerings. I notice that this list doesn't include Intel's latest core (Golden Cove). Do you have those benchmarks?

At the time I compiled it Golden Cove wasn’t out yet. Golden Cove has 19% higher IPC than Rocket Lake which would place it just above Zen 3 at a score of 175.6.

Thank you.

So my real question is: will I see a noticeable improvement when playing games? Especially World of Warcraft, which is a super old codebase that relies heavily on cpu.

I have a 3090 as my GPU which is overkill for WoW so I’m mostly wondering about whether the single-threaded performance of the new chip at 5GHz will be much more than my current chip, given that it’s running at 5GHz vs. the default 3.7GHz.

The new gen of Intel chips is somewhat notable because despite AMD fanboys (that's what they are) saying hurr-durr TDP they are very efficient gaming chips (i.e. realistic workloads), so yes it will be a win. They are absolute monsters on a single-thread. Might be worth waiting for Zen4 / raptor lake, at very least for a price drop.

I really doubt you will experience any improvement.

What kind of noticeable improvement do you expect? Are you below 60fps today? Are you waiting for game to load? Do you want to upgrade from 1080 to 4K?

Basically, what is your bottleneck? If you don’t have any visible such, what’s left to improve? I was under the impression WoW was so old that any gaming rig from the last decade would have no problem to run it.

Reply on news.ycombinator.com