[hyperrail]

I think of AMD's current approach - a microarchitecture with slower cores, but more cores, than Intel - as very similar to what Sun/Oracle tried to do from 2005 to 2010 with the Niagara family (UltraSPARC T1-T3).

Each core in those chips was seriously underclocked compared to a Xeon of similar vintage and price point (1-1.67 GHz; compared to 1.6 GHz to 3 or more), and lacked features like out-of-order execution and big caches that are almost minimum requirements for a modern server CPU. Sun hoped to make up for the slow cores in server applications with having more cores and having multiple threads per core (though with a simpler technology than SMT/hyper-threading).

However, Oracle eventually decided to focus on single-threaded performance with its more recent chips - it turns out that no OoO and < 2 GHz nominal speeds look pretty bad for many server applications. My suspicion is that even though the CPU-bound parts of games are becoming more multi-threaded, AMD will be forced to fix its slower architecture or lose out to Intel again in the server AND high-end desktop markets in a few years.

[wmf]

It's not similar at all. AMD's cores are 10-20% slower while Niagara was 80-90% slower. And AMD isn't intentionally slower; they designed the Zen core for maximum single-thread performance but they just didn't do as good a job as Intel because their budget is vastly smaller.

[sliken]

Just figured I'd mention that AMD significantly closed this gap with the Ryzen 2. The less parallel friendly applications (like many games) now seem to be faster on AMD or Intel depending on the application. Additionally the up to date security patches tend to hurt Intel more than AMD.

As always, if you really care about a single application, then you test it. But I wouldn't say that Intel wins on all single thread or few thread workloads anymore.

Especially if you consider that often a new Intel CPU requires a new Intel motherboard, and AMD often keeps motherboard compatibility across multiple generations, like the Ryzen and Ryzen 2.

[xxs]

Well, you can mod Z170 actually. Intel played super duper greedy and made a Z370 requirement.

Even Z170 can run 8700K, [0] Z170 (and Z270) needs a cooked bios and the cpu needs a pin short (easy with a pencil 4B) --- and it can even be overclocked if the motherboard VRM is good enough.

[0]: https://community.hwbot.org/topic/175489-asrock-z170-mocf-li...

[dmichulke]

A slightly OT question:

Wasn't that 10-20% before meltdown? Or is there still some similar disadvantage in clock speed per Watt or IPC?

[loeg]

AMD still takes the hit for Spectre mitigations, even if it does not need Meltdown mitigation.

And I'm not sure it's possible to fairly discount Intel's performance with meltdown mitigations applied. I think the impact will vary depending on workload.

[dmichulke]

> AMD still takes the hit for Spectre mitigations, even if it does not need Meltdown mitigation.

That's why I wanted to keep it out of the discussion and just mentioned Meltdown, AFAIK Spectre applies to both so it would be pure speculation to identify who'll be hit harder.

> And I'm not sure it's possible to fairly discount Intel's performance with meltdown mitigations applied. I think the impact will vary depending on workload.

I think we have this problem already all the time (with or without mitigations applied), that's why we (should) interpret benchmarks only as a proxy.

[loeg]

> That's why I wanted to keep it out of the discussion and just mentioned Meltdown, AFAIK Spectre applies to both so it would be pure speculation to identify who'll be hit harder.

That makes sense. Many people conflate the two, so I just wanted to be explicit about what I was saying :-).

> I think we have this problem already all the time (with or without mitigations applied), that's why we (should) interpret benchmarks only as a proxy.

That's totally reasonable. I think there were some discussions of the impact of the Meltdown patch (on Intel performance) on the LKML list at the time the patch(es) were being reviewed. (Other OS may have different perf impact for their Meltdown mitigations, of course, but it helps ballpark.)

Here's some discussion on anandtech, although it doesn't measure Spectre mitigations alone vs Spectre+MD; only base, MD alone, and MD+Spectre:

https://www.anandtech.com/show/12566/analyzing-meltdown-spec...

[spacenick88]

Afaik not, at least on Linux the mitigations are turned on as needed by CPU ID data

[paulmd]

Meltdown mitigation doesn't affect consumer workloads much. Database and server workloads are hit a lot harder.

[snuxoll]

Zen does a decent job in clock-for-clock performance, huge killer on the desktop is raw clock speed. When you pit a Ryzen chip maxing out around 3.8-4.2GHz (depending on generation and silicon lottery) to an i7-8700K that has a base frequency of 4.7GHz it's pretty obvious which is going to come out on top.

Most of that clock hit comes from the 12nm LPP process that AMD is currently using too from what I can tell, low-power process typically equates to lower clocks (see mobile chips) so it's not surprising - and why Zen 2 being based on GloFo's 7nm process will hopefully close that gap.

[nottorp]

Is it such a huge killer outside gaming benchmarks? And even then, the extra power is useful only if you jumped on the 4K bandwagon.

Personally, consider the amount of random crap that i run, I'd rather have more cores. And more importantly, 80% of the performance for 50% of the price is just fine(tm).

[zaarn]

The gaming benchmarks are a bit meh since in most realistic builds the GPU will be the bottleneck, not the CPU (unless you buy a 1080Ti with a Ryzen 3 or i3, though in that case all help is lost).

More cores do benefit if you run stuff besides the game, which most people do.

[nottorp]

I'm into VM abuse, so for me more cores would be a no brainer...

Sadly for AMD that would be IF i needed a new machine. My 2012 Core i7 still seems to be enough for my needs. (Except the GPU, that I changed recently.)

[zaarn]

I feel you there, I was using a i5 2500 since it came out until last year march when I switched to ryzen. A very good CPU indeed.

[xxs]

>i7-8700K that has a base frequency of 4.7GH.

That's not base at any rate, you can't get all cores at 4.7Ghz stock, 4.7 is a turbo-boost single core. No way you get that w/o a pretty decent cooler on a non-delidded CPU unless happen to have a chip that requires no extra voltage at all.

It's true that many games are predominantly single core, though but it's likely to get a single core 4.5Ryzen as well.

[bufferoverflow]

i7-8700K base frequency is 3.7 GHz, not 4.7

https://ark.intel.com/products/126684/Intel-Core-i7-8700K-Pr...

[snuxoll]

Oops, fat fingered that one.

[kankroc]

This is a gross overestimate of how far behind AMD is in single core performance. We're talking a few lost frames per second in games not some crazy sun vs oracle stuff.

[tutanchamun]

https://i.imgur.com/dpfu5K3.png

Intel is mainly faster because of a significant clock advantage. Clock for clock the advantage is small.