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.
574 Comments
View All Comments
rudolphna - Thursday, March 2, 2017 - link
Demonizing gamers in your post does nothing to contribute to your credibility, and will only turn off more well reasoned people from listening, or caring, about your opinion.samer1970 - Friday, March 3, 2017 - link
Gamers dont buy 8 cores chips .. If you want good AMD gaming chip at very low price , wait for the 6 and 4 cores Ryzen and then judge ...I expect the 4 cores/8 threads Ryzen at 150$ to blow Intel to pieces ... SOON ..
Imagine a 4.5Ghz AMD Ryzen 4 cores for $150 then talk .
Sttm - Friday, March 3, 2017 - link
4 cores that are noticeably slower than Intel's 4 cores, which sell in a handsome i5 package for $200. I think they need a software miracle and they need it fast to win over the gaming crowd.Cooe - Sunday, February 28, 2021 - link
Bet you're feeling like a massive idiot now if you actually got that 4c/4t Kaby Lake i5 over a 6c/12t Ryzen 5 1600. It was about as fast at 1080p gaming in 2017 as the R5, but nowadays isn't even in the same UNIVERSE as the Ryzen chip. Let alone the performance difference for literally EVERYTHING else.Diji1 - Thursday, March 2, 2017 - link
Hurr durr you don't like what I like so you're a dumbo making me smarter than you! (yes, I know but they cannot see it themselves because their so smart in their own imagination).JoeyJoJo123 - Thursday, March 2, 2017 - link
What exactly are you trying to say here?Holliday75 - Thursday, March 2, 2017 - link
I think it was "Hurr durr".BikeDude - Friday, March 3, 2017 - link
sounded more like 'hold door' to me?star-affinity - Thursday, March 2, 2017 - link
I didn't know what is considered "wasting your life" is objective – please elaborate. What do you do with your life that makes it better than someone who likes to plays RPGs?Dug - Friday, March 3, 2017 - link
I'm so glad you are the one to judge what people are when they play games. Your insight and thought process is inspiring.I'm only to guess that what you do with a computer is going to change the world.