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 ESTSimultaneous MultiThreading (SMT)
Zen will be AMD’s first foray into a true simultaneous multithreading structure, and certain parts of the core will act differently depending on their implementation. There are many ways to manage threads, particularly to avoid stalls where one thread is blocking another that ends in the system hanging or crashing. The drivers that communicate with the OS also have to make sure they can distinguish between threads running on new cores or when a core is already occupied – to achieve maximum throughput then four threads should be across two cores, but for efficiency where speed isn’t a factor, perhaps power gating/clock gating half the cores in a CCX is a good idea.
There are a number of ways that AMD will deal with thread management. The basic way is time slicing, and giving each thread an equal share of the pie. This is not always the best policy, especially when you have one performance dominant thread, or one thread that creates a lot of stalls, or a thread where latency is vital. In some methodologies the importance of a thread can be tagged or determined, and this is what we get here, though for some of the structures in the core it has to revert to a basic model.
With each thread, AMD performs internal analysis on the data stream for each to see which thread has algorithmic priority. This means that certain threads will require more resources, or that a branch miss needs to be prioritized to avoid long stall delays. The elements in blue (Branch Prediction, INT/FP Rename) operate on this methodology.
A thread can also be tagged with higher priority. This is important for latency sensitive operations, such as a touch-screen input or immediate user input elements required. The Translation Lookaside Buffers work in this way, to prioritize looking for recent virtual memory address translations. The Load Queue is similarly enabled this way, as typically low latency workloads require data as soon as possible, so the load queue is perfect for this.
Certain parts of the core are statically partitioned, giving each thread an equal timing. This is implemented mostly for anything that is typically processed in-order, such as anything coming out of the micro-op queue, the retire queue and the store queue. However, when running in SMT mode but only with a single thread, the statically partitioned parts of the core can end up as a bottleneck, as they are idle half the time.
The rest of the core is done via competitive scheduling, meaning that if a thread demands more resources it will try to get there first if there is space to do so each cycle.
New Instructions
AMD has a couple of tricks up its sleeve for Zen. Along with including the standard ISA, there are a few new custom instructions that are AMD only.
Some of the new commands are linked with ones that Intel already uses, such as RDSEED for random number generation, or SHA1/SHA256 for cryptography (even with the recent breakthrough in security). The two new instructions are CLZERO and PTE Coalescing.
The first, CLZERO, is aimed to clear a cache line and is more aimed at the data center and HPC crowds. This allows a thread to clear a poisoned cache line atomically (in one cycle) in preparation for zero data structures. It also allows a level of repeatability when the cache line is filled with expected data. CLZERO support will be determined by a CPUID bit.
PTE (Page Table Entry) Coalescing is the ability to combine small 4K page tables into 32K page tables, and is a software transparent implementation. This is useful for reducing the number of entries in the TLBs and the queues, but requires certain criteria of the data to be used within the branch predictor to be met.
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bobsta22 - Saturday, March 4, 2017 - link
Office with 20 PCs - all developers - loads of VMs and containers.All the PCs are due a CPU/Gfx refresh, but ITX mobos required.
Cant wait tbh. This is a game changer.
prisonerX - Saturday, March 4, 2017 - link
What if they come out with a 16 core line next year!bobsta22 - Saturday, March 4, 2017 - link
What?lilmoe - Tuesday, March 7, 2017 - link
It really is. As a freelance developer, I can't wait.ericgl21 - Saturday, March 4, 2017 - link
For me, the more important thing to see from AMD is if they can come up with a chip that can beat the mobile Core i7-7820HQ (4c/8t no ECC) & the Xeon E3-1575M v5 (4c/8t with ECC), for less money.And the number of PCIe gen3 lanes is very important, especially with the rise of M.2 NVMe storage sticks.
cmagic - Sunday, March 5, 2017 - link
Will anandtech review Ryzen in gaming? I would really like Anandtech view, since I don't really trust other sites especially those "entertainment" sites. Want to see how Anandtech dive into its main cause.Tchamber - Sunday, March 5, 2017 - link
@cmagicPage 15
2017 GPU
The bad news for our Ryzen review is that our new 2017 GPU testing stack not yet complete. We recieved our Ryzen CPU samples on February 21st, and tested in the hotel at the event for 6hr before flying back to Europe.
I just ordered my 1700X, I plan to keep it for at least 5 years, as my needs don't change much. My current Intel 6 core is coming up on 7 years old now. I like to buy high end and use it a long time.
Lazlo Panaflex - Monday, March 6, 2017 - link
Same here...probably gonna grab a 1700 at some point and put this here i5-2500 non-k in the kids computer.asH98 - Sunday, March 5, 2017 - link
'''The BIG QUESTION is WHY are the HEDT benchmarks (professional ie Blender) fairer than gaming benchmarks??Bottom line is that CUTTING-EDGE CODING is happening NOW in AI, HPC, data, and AV/AR, game coders because of $$$ are the last to change or learn unless forced (great for NVidia Intel) so most of the game coding is stuck in yesteryear- Bethesda will be the test bed for game coders to move forward
Hence the difference in game benchmarks vs 'professional' (HEDT) benchmarks. Game coders can get stuck using yesterday's code without repercussions and consequences as long as old hardware dominates and there are no incentives to change or learn new skills. The same Cant happen in the Professional area where speed is tantamount to performance and $$$
TheJian - Sunday, March 5, 2017 - link
I hope you're going to test a dozen games at 1080p where most of us run for article #2 and the GAMING article should come in a week not 1/2 year later like 1080/1070 gtx reviews...LOL. As this article just seems like AMD told you "guys, please don't run any games so we can sell some chips to suckers before they figure out games suck". And you listened. No point in testing 1440p or 4k for CPU, and 95% of us run 1920x1200 and BELOW so you should be testing your games there for a CPU test.The fact they are talking Zen2 instead of fixing Zen1 kind of makes me think most of the gaming is NOT going to be fixable.
http://www.legitreviews.com/amd-ryzen-7-1800x-1700...
149fps for 7700 in theif vs. 108 for 1800x? JEEZ. GTA5 again, 163 to 138. Deus ex MD 127 to 103. These are massive losses to Intel's chip and Deus was clearly gpu bound as many of Intel's chips hit the same 127fps including my old 4790k :( OUCH AMD.
https://www.guru3d.com/articles_pages/amd_ryzen_7_...
Tombraider same 7700k vs. 1800x 132fps to 114 (never mind 6850 scoring 140fps). This will probably get worse as we move to 1080ti, vega, nvidia refresh for xmas, Volta, 10nm etc. If you were using a faster gpu the cpus will separate even more especially if people are mostly gaming at 1080p. Even if many move to 1440p, that maybe fixes some games (tombraider is one with 1080 regular that hits a wall at 90fps), but again goes back to major losses as we move to 10nm etc. We get 10nm chips for mobile now and gpus probably next year at 12nm (real? fake 12nm? Either way) and might squeak into 2017 (volta, TSMC). 10nm gpus will likely come 2018 at the latest. Those gpus will make 1440p look like 1080p today surely and cpus will again spread out (and no, we won't all be running 4k then...LOL). You could see cpus smaller than 10nm BEFORE you upgrade your cpu again if you buy this year. That could get pretty ugly if the benchmarks around the web for gaming are not going to improve. One more point you'll likely be looking at GDDR6 (16Gbps probably) for vid cards allowing them to possibly stretch their legs even more if needed. Again, all not good for a gamer here IMHO.
“But Senior Engineer Mike Clark says he knows where the easy gains are for Zen 2, and they're already working through the list”
So maybe no fix in sight for Zen1? Just excuses like "run higher res, and code right guys"...I hope that isn't the best they've got. I could go on about games, but most should get the point. I was going to buy ryzen purely for Handbrake, but I'll need to see motherboard improvements and at least some movement on gaming VERY soon.
One more ouch statement from pcper.
https://www.pcper.com/news/Processors/AMD-responds...
"For buyers today that are gaming at 1080p, the situation is likely to remain as we have presented it going forward."
So they don't think a fix is coming based on AMD info and as noted as gpus get much faster (along with their memory speeds) expect 1440p to look like today's 1080p benchmarks at least to some extent.
The board part is of major interest to me, so I can wait a bit and also see Intel's response. So AMD has be hanging for a bit here, but not for too long. I do like the pro side of these though (handbrake especially, just not quite enough).