What Makes Ryzen Tick
We have been exposed to details about the Zen architecture for the past several Hot Chips conventions as well as other points of information directly from AMD. Zen was a clean sheet design that borrowed some of the best features from the Bulldozer and Jaguar architectures, as well as integrating many new ideas that had not been executed in AMD processors before. The fusion of ideas from higher performance cores, lower power cores, and experience gained in APU/GPU design have all come together in a very impressive package that is the Ryzen CPU.
It is well known that AMD brought back Jim Keller to head the CPU group after the slow downward spiral that AMD entered in CPU design. While the Athlon 64 was a tremendous part for the time, the subsequent CPUs being offered by the company did not retain that leadership position. The original Phenom had problems right off the bat and could not compete well with Intel’s latest dual and quad cores. The Phenom II shored up their position a bit, but in the end could not keep pace with the products that Intel continued to introduce with their newly minted “tic-toc” cycle. Bulldozer had issues out of the gate and did not have performance numbers that were significantly greater than the previous generation “Thuban” 6 core Phenom II product, much less the latest Intel Sandy Bridge and Ivy Bridge products that it would compete with.
AMD attempted to stop the bleeding by iterating and evolving the Bulldozer architecture with Piledriver, Steamroller, and Excavator. The final products based on this design arc seemed to do fine for the markets they were aimed at, but certainly did not regain any marketshare with AMD’s shrinking desktop numbers. No matter what AMD did, the base architecture just could not overcome some of the basic properties that impeded strong IPC performance.
The primary goal of this new architecture is to increase IPC to a level consistent to what Intel has to offer. AMD aimed to increase IPC per clock by at least 40% over the previous Excavator core. This is a pretty aggressive goal considering where AMD was with the Bulldozer architecture that was focused on good multi-threaded performance and high clock speeds. AMD claims that it has in fact increased IPC by an impressive 54% from the previous Excavator based core. Not only has AMD seemingly hit its performance goals, but it exceeded them. AMD also plans on using the Zen architecture to power products from mobile products to the highest TDP parts offered.
The Zen Core
The basis for Ryzen are the CCX modules. These modules contain four Zen cores along with 8 MB of shared L3 cache. Each core has 64 KB of L1 I-cache and 32 KB of D-cache. There is a total of 512 KB of L2 cache. These caches are inclusive. The L3 cache acts as a victim cache which partially copies what is in L1 and L2 caches. AMD has improved the performance of their caches to a very large degree as compared to previous architectures. The arrangement here allows the individual cores to quickly snoop any changes in the caches of the others for shared workloads. So if a cache line is changed on one core, other cores requiring that data can quickly snoop into the shared L3 and read it. Doing this allows the CPU doing the actual work to not be interrupted by cache read requests from other cores.
Each core can handle two threads, but unlike Bulldozer has a single integer core. Bulldozer modules featured two integer units and a shared FPU/SIMD. Zen gets rid of CMT for good and we have a single integer and FPU units for each core. The core can address two threads by utilizing AMD’s version of SMT (symmetric multi-threading). There is a primary thread that gets higher priority while the second thread has to wait until resources are freed up. This works far better in the real world than in how I explained it as resources are constantly being shuffled about and the primary thread will not monopolize all resources within the core.
Subject: Processors | February 21, 2017 - 10:54 AM | Sebastian Peak
Tagged: ryzen, rumor, report, R7, processor, leak, IPC, cpu, Cinebench, benchmark, amd, 1700X
The Ryzen 7 1700X is reportedly an 8-core/16-thread processor with a base clock speed of 3.40 GHz, and while overall performance from the leaked benchmarks looks very impressive, it is the single-threaded score from the Cinebench R15 run pictured which really makes this CPU look like major competition for Intel with IPC.
An overall score of 1537 is outstanding, placing the CPU almost even with the i7-6900K at 1547 based on results from AnandTech:
Image credit AnandTech
And the single-threaded performance score of the reported Ryzen 7 1700X is 154, which places it above the i7-6900K's score of 153. (It is worth noting that Cinebench R15 shows a clock speed of 3.40 GHz for this CPU, which is the base, while CPU-Z is displaying 3.50 GHz - likely indicating a boost clock, which can reportedly surpass 3.80 GHz with this CPU.)
Other results from the reported leak include 3DMark Fire Strike, with a physics score of 17,916 with Ryzen 7 1700X clocking in at ~3.90 GHz:
We will know soon enough where this and other Ryzen processors stand relative to Intel's current offerings, and if Intel will respond to the (rumored) price/performance double whammy of Ryzen. An i7-6900K retails for $1099 and currently sells for $1049 on Newegg.com, and the rumored pricing (taken from Wccftech), if correct, gives AMD a big win here. Competition is very, very good!
Chart credit Wccftech.com