AMD Zen Microarchitecture: Dual Schedulers, Micro-Op Cache and Memory Hierarchy Revealed
by Ian Cutress on August 18, 2016 9:00 AM ESTSimultaneous Multi-Threading
On Zen, each core will be able to support two threads in what is called ‘simulatenous multi-threading’. Intel has supported their version of SMT for a number of years, and other CPU manufacturers like IBM support up to 8 threads per core on their POWER8 platform designs. Building a core to be able to use multiple threads can be tough, as it requires a lot of resources to make sure that the threads do not block each other by consuming all the cache and buffers in play. But AMD will equip Zen with SMT which means we will see 8C/16T parts hitting the market.
Unlike Bulldozer, where having a shared FP unit between two threads was an issue for floating point performance, Zen’s design is more akin to Intel’s in that each thread will appear as an independent core and there is not that resource limitation that BD had. With sufficient resources, SMT will allow the core instructions per clock to improve, however it will be interesting to see what workloads will benefit and which ones will not.
Timeframe and Availability
At the presentation, it was given that Zen will be available in volume in 2017. As the AM4 platform will share a socket with Bristol Ridge, users are likely to see Bristol Ridge systems from AMD’s main OEM partners, like Dell and others, enter the market before separate Zen CPUs will hit the market for DIY builders. It’s a matter of principle that almost no consumer focused semiconductor company releases a product for the sale season, and Q1 features such events as CES, which gives a pretty clear indication of when we can expect to get our hands on one.
It’s worth noting that AMD said that as we get closer to launch, further details will come as well as deeper information about the design. It was also mentioned that the marketing strategy is also currently being determined, such that Zen may not actually be the retail product name for the line of processors (we already have Summit Ridge as the platform codename, but that could change for retail as well).
Wrap Up
AMD has gone much further into their core design than I expected this week. When we were told we had a briefing, and there were 200-odd press and analysts in the room, I was expecting to hear some high level puff about the brand and a reiteration of their commitment to the high end. To actually get some slides detailing parts of the microarchitecture, even at a basic cache level, was quite surprising and it somewhat means that AMD might have stolen the show with the news this week.
We’ve got another couple of pieces detailing some of the AMD internal/live benchmark numbers during the presentation, as well as the dual socket server platform, the 32-core Naples server CPU, and what we saw at the event in terms of motherboard design.
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patel21 - Friday, August 19, 2016 - link
Actually whom are you asking these questions ?Peichen - Friday, August 19, 2016 - link
Lets hope this isn't another one of AMD's empty claim that we've all seen like 8 times over the last 10 years on both CPU, GPU and the nonsense APU.The stock tripled over the last 12 months but that's only if Zen can deliver. If Zen is another <fill in AMD product for the last 10 years>, AMD will be a dollar stock again.
mxnerd - Friday, August 19, 2016 - link
Wow. AMD stock climbs 12.5% after the news.jihe - Friday, August 19, 2016 - link
I pray to god this is a worthwhile processorjust4U - Friday, August 19, 2016 - link
All it really needs to be is competitive on the performance front. It doesn't need to beat Intel but hey if it can well shoot.. that would be interesting. Not expecting that or even hoping for it since I think that would be unrealistic.cocochanel - Friday, August 19, 2016 - link
If Zen is good enough, it'll take some market share away from Intel, but not much since Intel CPU's are pretty much state of the art. However, the real advantages will come with their APU's (Zen + Polaris). The upcoming PlayStation Neo and Xbox Scorpio will use them. AMD will also go after mobile since they have no completion there with their APU's. Intel has some powerful iGPU's but they are nowhere near AMD APU's in performance. With the node disadvantage gone away, performance and power consumption should be up there. I know the desktop diehards will disagree, but desktops sales have been falling for years. Likely causes are a move by many to mobile devices and cheap, powerful gaming consoles. I don't see that trend changing. The ARM ecosystem is also rolling along and now it's beginning to creep into so far, exclusive x86 server markets. VR will also force ARM designers to come up with more powerful hardware. The next 5-10 years should be interesting.Michael Bay - Friday, August 19, 2016 - link
Problem is, mobile itself has reached saturation and isn`t so attractive anymore. Plus, what AMD is to go there with, x86? Intel tried already.Node disadvantage will come back at some point, simply because it`s a matter of survival for intel.
Where things should get interesting is the server side. ARM is hardly a threat, but AMD might have a good product here with GPU+CPU compute, likely at lower price.
cocochanel - Friday, August 19, 2016 - link
My mistake. By mobile, I meant laptops and not tablets. It's still a big market.Intel regaining node advantage ? Mmm, from I have seen in tech reports ( and I am not a big expert ), both 10nm and 7nm will be a tough nut to crack and will cost huge amounts. Compared to years past, Intel is now up against big giants ( Samsung and TSMC ) who are making billions every year selling tons of ARM SoC and have the deep pockets needed for new nodes. The South Koreans and the Chinese are a smart bunch. I mean, look at the SSD market. Intel had a lock on that until Samsung decided that one was too many. Remember Thunderbold ? Nice tech, but now the market is moving away from it. Sadly, even for mighty Intel, the landscape has changed.
I hope you're right about the server market. AMD can use any sales they can get, but then again, Intel has a lock on that and they will get aggressive and mean if necessary ( it's big bucks, you know).
ARM not a threat ? Architecturally speaking, they have advantages, after all, x86 is a dinosaur and ARM business model is one of their biggest strengths. But you're right, the installed base for x86 is huge and it will take time. There are some big names, however ( Qualcomm and others ) pouring some serious money in it.
Should be interesting.
Michael Bay - Saturday, August 20, 2016 - link
x86 is a very functional dinosaur with A LOT of companies standing behind it. ARM can license all they want, to actually break in and make those huge server monies, you need a full sw/hw/oem stack.I`d look at IBM`s last hooray POWER thing as the real competitor for intel right now, with AMD hopefully coming in soon as well.
BillBear - Saturday, August 20, 2016 - link
Google has announced their intention to open up competition in the server space by fully adopting IBM's POWER chips over their entire server software/hardware stack and is working with AMD and others to make sure they can do the same thing with the ARM based server chips in development.Competition is a good thing.