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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Notmyusualid - Saturday, March 4, 2017 - link
Can't disagree with you pal. They look like they execptional value for money.I on the other hand, am already on LGA2011-v3 platform, so I won't be changing, but the main point here is - AMD are back. And we welcome them too.
Alexvrb - Saturday, March 4, 2017 - link
Yeah... if the pricing is as good as rumored for the Ryzen 5, I may pick up a quad-core model. Gives me an upgrade path too, maybe a Ryzen+ hexa or octa-core down the road. For budget builds that Ryzen 3 non-SMT quad-core is going to be hard to argue with though.wut - Sunday, March 5, 2017 - link
You're really optimistically assuming things.Kaby Lake Core i5 7400 $170
Ryzen 5 1600X $259
...and single thread benchmark shows Core i5 to be firmly ahead, just as Core i7 is. The story doesn't seem to change much in the mid range.
Meteor2 - Tuesday, March 7, 2017 - link
@wut spot-on. It also seems that Zen on GloFlo 14 nm doesn't clock higher than 4.0 GHz. Zen has lower IPC and lower actual clocks than Intel KBL.Whichever way you cut it, however many cores in a chip are being considered, in terms of performance, Intel leads. Intel's pricing on >4 core parts is stupid and AMD gives them worthy price competition here. But at 4C and below, Intel still leads. AMD isn't price-competitive here either. No wonder Intel haven't responded to Zen. A small clock bump with Coffee Lake and a slow move to 10 nm starting with Cannon Lake for mobile CPUs (alongside or behind the introduction of 10 nm 'datacentre' chips) is all they need to do over the next year.
After all, if Intel used the same logic as TSMC and GloFlo in naming their process nodes, i.e. using the equivalent nanometre number of if finFETs weren't being used, Intel would say they're on a 10 nm process. They have a clear lead over GloFlo and thus anything AMD can do.
Cooe - Sunday, February 28, 2021 - link
I'm here from the future to tell you that you were wrong about literally everything though. AMD is kicking Intel's ass up and down the block with no end in sight.Cooe - Sunday, February 28, 2021 - link
Hahahaha. I really fucking hope nobody actually took your "buying advice". The 6-core/12-thread Ryzen 5 1600 was about as fast at 1080p gaming as the 4c/4t i5-7400 ON RELEASE in 2017, and nowadays with modern games/engines it's like TWICE AS FAST.deltaFx2 - Saturday, March 4, 2017 - link
I think the reviewer you're quoting is Gamers Nexus. He doesn't come across as being a particularly erudite person on matters of computer architecture. He throws a bunch of tests at it, and then spews a few untutored opinions, which may or may not be true. Tom's hardware does a lot of the same thing, and more, and their opinions are far more nuanced. Although they too could have tried to use an AMD graphics card to see if the problems persist there as well, but perhaps time was the constraint.There's the other question of whether running the most expensive GPU at 1080p is representative of real-world performance. Gaming, after all, is visual and largely subjective. Will you notice a drop of (say) 10 FPS at 150 FPS? How do you measure goodness of output? Let's contrive something.
All CPUs have bottlenecks, including Intel. The cases where AMD does better than Intel are where AMD doesn't have the bottlenecks Intel has, but nobody has noticed it before because there wasn't anything else to stack up against it. The question that needs to be answered in the following weeks and months is, are AMD's bottlenecks fixable with (say) a compiler tweak or library change? I'd expect much of it is, but lets see. There was a comment on some forum (can't remember) that said that back when Athlon64 (K8) came out, the gaming community was certain that it was terrible for gaming, and Netburst was the way to go. That opinion changed pretty quickly.
Notmyusualid - Saturday, March 4, 2017 - link
Gamers Nexus seem 'OK' to me. I don't know the site like I do Anandtech, but since Anand missed out the games....I am forced to make my opinions elsewhere. And funny you mentions Toms, they seem to back it up to some degree too, and I know these two sites are cross-owned.
But still, when Anand get around to benching games with Ryzen, only then will I draw my final conclusions.
deltaFx2 - Sunday, March 5, 2017 - link
@ Notmyusualid: I'm sure Gamers Nexus numbers are reasonable. I think they and Tom's (and other reviewers) see a valid bottleneck that I can only guess is software optimization related. The issue with GN was the bizarre and uninformed editorializing. Comments like, the workloads that AMD does well at are not important because they can be accelerated on GPU (not true, but if true, why on earth did GN use it in the first place?). There are other cases where he drops i5s from evaluation for "methodological reasons" but then says R7 == i5. Even based on the tests he ran, this is not true. Anyway, the reddit link goes over this in far more detail than I could (or would).Meteor2 - Tuesday, March 7, 2017 - link
@DeltaFX2 in what way was GamersNexus conclusion that tasks that can be pushed to GPUs should be incorrect? Are you saying Premiere and Blender can't be used on GPUs?GN's conclusion was:
"If you’re doing something truly software accelerated and cannot push to the GPU, then AMD is better at the price versus its Intel competition. AMD has done well with its 1800X strictly in this regard. You’ll just have to determine if you ever use software rendering, considering the workhorse that a modern GPU is when OpenCL/CUDA are present. If you know specific in stances where CPU acceleration is beneficial to your workflow or pipeline, consider the 1800X."
I think that's very fair and a very good summary of Ryzen.