The AMD Zen and Ryzen 7 Review: A Deep Dive on 1800X, 1700X and 1700
by Ian Cutress on March 2, 2017 9:00 AM ESTThoughts and Comparisons
Throughout AMD's road to releasing details on Zen, we have had a chance to examine the information on the microarchitecture often earlier than we had expected to each point in the Zen design/launch cycle. Part of this is due to the fact that internally, AMD is very proud of their design, but some extra details (such as the extent of XFR, or the size of the micro-op cache), AMD has held close to its chest until the actual launch. With the data we have at hand, we can fill out a lot of information for a direct comparison chart to AMD’s last product and Intel’s current offerings.
| CPU uArch Comparison | ||||
| AMD | Intel | |||
| Zen 8C/16T 2017 |
Bulldozer 4M / 8T 2010 |
Skylake Kaby Lake 4C / 8T 2015/7 |
Broadwell 8C / 16T 2014 |
|
| L1-I Size | 64KB/core | 64KB/module | 32KB/core | 32KB/core |
| L1-I Assoc | 4-way | 2-way | 8-way | 8-way |
| L1-D Size | 32KB/core | 16KB/thread | 32KB/core | 32KB/core |
| L1-D Assoc | 8-way | 4-way | 8-way | 8-way |
| L2 Size | 512KB/core | 1MB/thread | 256KB/core | 256KB/core |
| L2 Assoc | 8-way | 16-way | 4-way | 8-way |
| L3 Size | 2MB/core | 1MB/thread | >2MB/cire | 1.5-3MB/core |
| L3 Assoc | 16-way | 64-way | 16-way | 16/20-way |
| L3 Type | Victim | Victim | Write-back | Write-back |
| L0 ITLB Entry | 8 | - | - | - |
| L0 ITLB Assoc | ? | - | - | - |
| L1 ITLB Entry | 64 | 72 | 128 | 128 |
| L1 ITLB Assoc | ? | Full | 8-way | 4-way |
| L2 ITLB Entry | 512 | 512 | 1536 | 1536 |
| L2 ITLB Assoc | ? | 4-way | 12-way | 4-way |
| L1 DTLB Entry | 64 | 32 | 64 | 64 |
| L1 DTLB Assoc | ? | Full | 4-way | 4-way |
| L2 DTLB Entry | 1536 | 1024 | - | - |
| L2 DTLB Assoc | ? | 8-way | - | - |
| Decode | 4 uops/cycle | 4 Mops/cycle | 5 uops/cycle | 4 uops/cycle |
| uOp Cache Size | 2048 | - | 1536 | 1536 |
| uOp Cache Assoc | ? | - | 8-way | 8-way |
| uOp Queue Size | ? | - | 128 | 64 |
| Dispatch / cycle | 6 uops/cycle | 4 Mops/cycle | 6 uops/cycle | 4 uops/cycle |
| INT Registers | 168 | 160 | 180 | 168 |
| FP Registers | 160 | 96 | 168 | 168 |
| Retire Queue | 192 | 128 | 224 | 192 |
| Retire Rate | 8/cycle | 4/cycle | 8/cycle | 4/cycle |
| Load Queue | 72 | 40 | 72 | 72 |
| Store Queue | 44 | 24 | 56 | 42 |
| ALU | 4 | 2 | 4 | 4 |
| AGU | 2 | 2 | 2+2 | 2+2 |
| FMAC | 2x128-bit | 2x128-bit 2x MMX 128-bit |
2x256-bit | 2x256-bit |
Bulldozer uses AMD-coined macro-ops, or Mops, which are internal fixed length instructions and can account for 3 smaller ops. These AMD Mops are different to Intel's 'macro-ops', which are variable length and different to Intel's 'micro-ops', which are simpler and fixed-length.
Excavator has a number of improvements over Bulldozer, such as a larger L1-D cache and a 768-entry L1 BTB size, however we were never given a full run-down of the core in a similar fashion and no high-end desktop version of Excavator will be made.
This isn’t an exhaustive list of all features (thanks to CPU World, Real World Tech and WikiChip for filling in some blanks) by any means, and doesn’t paint the whole story. For example, on the power side of the equation, AMD is stating that it has the ability to clock gate parts of the core and CCX that are not required to save power, and the L3 runs on its own clock domain shared across the cores. Or the latency to run certain operations, which is critical for workflow if a MUL operation takes 3, 4 or 5 cycles to complete. We have been told that the FPU load is two cycles quicker, which is something. The latency in the caches is also going to feature heavily in performance, and all we are told at this point is that L2 and L3 are lower latency than previous designs.
A number of these features we’ve already seen on Intel x86 CPUs, such as move elimination to reduce power, or the micro-op cache. The micro-op cache is a piece of the puzzle we wanted to know more about from day one, especially the rate at which we get cache hits for a given workload. Also, the use of new instructions will adjust a number of workloads that rely on them. Some users will lament the lack of true single-instruction AVX-2 support, however I suspect AMD would argue that the die area cost might be excessive at this time. That’s not to say AMD won’t support it in the future – we were told quite clearly that there were a number of features originally listed internally for Zen which didn’t make it, either due to time constraints or a lack of transistors.
We are told that AMD has a clear internal roadmap for CPU microarchitecture design over the next few generations. As long as we don’t stay for so long on 14nm similar to what we did at 28/32nm, with IO updates over the coming years, a competitive clock-for-clock product (even to Broadwell) with good efficiency will be a welcome return.
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lakerssuperman - Thursday, March 2, 2017 - link
People like me. I was previously running a 2600k overclocked. Nice chip. Still runs great, but I was looking for an upgrade about a year ago as one of the things I do a lot of is Handbrake conversion for my HTPC. Going to even the newest Intel 4 core got me maybe 20% improvement on one of my major workloads for insane amounts of money and going to the high end to get 8-10 cores was just not justifiable.I ended up buying a used Xeon/X79 motherboard combo for around $300 off ebay. 8 cores/16 threads and it works great for Handbrake. I lost some clock speed in the move so single thread performance took a bit of a hit, but was more than made up for in multi-thread performance. I can still game on this CPU just fine and I don't play the newest stuff right away anyway just because of time constraints.
The X79 platform is fine for what I'm doing with it. Would I like the new stuff? Sure. And if I was in the position I was last year looking for an upgrade I don't see how I wouldn't get an 1800x. It gives me the right balance of features for what I do with my computer.
If I was just gaming, I'd look at Intel currently because their 4 core i5 is the sweet spot for this. But I'm not just gaming so this chip is infinitely more attractive to someone like me. With the price and features I can't see how it isn't a winner and when the 4 and 6 core parts come out at likely higher frequencies, I think they are going to be the real winners for gaming.
rarson - Thursday, March 2, 2017 - link
Ryzen is clearly well-suited to anyone who values high performance in a multitude of usage scenarios over one single usage scenario, especially if one cares about how much money they need to spend to achieve those results.injurer - Friday, March 3, 2017 - link
1800X is definitely designed for enthusiast, and AMD fans, but when you go to 1700X this is a price killer targeting the mainstream. 1700 is on the same boat but at even lower price. All the 3 are 8 core chips and are quite close to the 6900K but at 2-4 times lower price.At the end I really believe AMD are still having to show us the real potential of their architecture. Those chips are just the start. Remember Ryzen design is a new from its core, so they definitely have room to ecpand and enhance it.
bill.rookard - Thursday, March 2, 2017 - link
Well, thing to remember is that for those looking for a new build, they now have a legitimate choice. I still do see in the future that things will only go more multithreaded, and even though the i7-7700k is still a great chip, having more physical cores and resources to throw at it will only help.To that end, again, anyone planning a NEW build from the ground up will be able to seriously consider a Ryzen system.
Worst case, think about it. In the deep dive they had mention of 'competitive resource sharing' with SMT enabled. If you were to disable SMT on Ryzen - it would give you 8 PHYSICAL cores versus the 4 physical/4 logical cores of the 7700k. Without those resources being partially used across 16 threads - all resources would be allocated to the physical cores instead, potentially allowing more processing power per physical core.
There's still quite a bit to be checked out and dug through.
lilmoe - Thursday, March 2, 2017 - link
This. I want 2 things dug deeper in follow ups:1) Single/multi threaded performance with SMT disabled VS SMT enabled.
2) Game comparisons with more sensible GPUs (which actually ship and sell in volume, IE: the ones people actually buy), like the GTX 1060 and/or RX 480.
BurntMyBacon - Friday, March 3, 2017 - link
@lilmoeI agree with 1). Intel had HT for several generations before it was universally better to leave it enabled (still needs to be disabled some times, but these are more the edge cases now).
Not so sure I'm onboard with 2). Pairing a $200 GPU with a $500 processor for gaming purposes seems a little backwards. I'd like to see that (GTX1060 / RX480) gaming comparison on a higher clocked R5 or R3 processor when they are released.
Meteor2 - Friday, March 3, 2017 - link
I'd rather see tests paired with a 1080 Ti. At RX480/1060 level, it's well known the bottleneck is GPU performance not CPU. A 1080 Ti should be fast enough to show up the CPU.lilmoe - Friday, March 3, 2017 - link
@BurntMyBacon @Meteor2Lots of people, like me, are more into CPU power. I'm OK with a mid-range GPU. Gaming is not my top priority, and when I do, It's never above 1080p.
It'd be interesting to see if there are differences. I wouldn't dismiss it, saying the GPU would be the bottleneck so fast.
bigboxes - Sunday, March 5, 2017 - link
I'm with you on that. Gaming is way down in my priority list. I do it occasionally just because I love to see what my hardware can do. I currently have a ultrawide 1080p monitor. When I move to 4K then hopefully midrange GPU will cover that. My CPU is a 4790K. It's great for most tasks. I've been wanting to go to 6/8 core for some time, but the cost for the platform was too high. I think in a couple of years I will seriously think about Ryzen when building a new workstation.rarson - Thursday, March 2, 2017 - link
I am interested in seeing potential improvement due to BIOS updates. Additionally, I'm interested in seeing potential improvement due to better multi-threaded software. My hunch is that AMD is either on-par or better than Intel, or maybe damn near that prediction, so I think the 4-core parts will compare well to the current Skylake SKUs. I also expect them to overclock better than the 8-core chips. I guess we'll just have to wait for them to release.8 physical cores is definitely better than 4 cores with SMT/HTT/whatever you want to call it.