AMD Ryzen 7 2700X and Ryzen 5 2600 Memory Performance
AMD Ryzen 7 2700X and Ryzen 5 2600 Memory Performance
Core Topology & Testing
Cores on Ryzen are grouped in blocks (CCX or compute units) each with its own 8MB L3 cache – but connected via a 256-bit bus running at memory controller clock. This is better than older designs like Intel Core 2 Quad or Pentium D which were effectively 2 CPU dies on the same socket – but not as good as a unified design where all cores are part of the same unit.
Running algorithms that require data to be shared between threads – e.g. producer/consumer – scheduling those threads on the same CCX would ensure lower latencies and higher bandwidth which we will test with presently.
We have thus modified Sandra’s ‘CPU Multi-Core Efficiency Benchmark‘ to report the latencies of each producer/consumer unit combination (e.g. same core, same CCX, different CCX) as well as providing different matching algorithms when selecting the producer/consumer units: best match (lowest latency), worst match (highest latency) thus allowing us to test inter-CCX bandwidth also. We hope users and reviewers alike will find the new features useful!
We are testing native arithmetic, SIMD and cryptography performance using the highest performing instruction sets (AVX2, AVX, etc.). Ryzen supports all modern instruction sets including AVX2, FMA3 and even more.
Results Interpretation: Higher rate values (GOPS, MB/s, etc.) mean better performance. Lower latencies (ns, ms, etc.) mean better performance.
Environment: Windows 10 x64, latest AMD and Intel drivers. 2MB “large pages” were enabled and in use. Turbo / Boost was enabled on all configurations.
Total Inter-Core Bandwidth – Best : Ryzen2 manages 15% higher bandwidth between its cores, slightly better than just 11% clock increase – signalling some improvements under the hood.
Total Inter-Core Bandwidth – Worst : In worst-case pairs on Ryzen must go across CCXes – and with this link running at the same clock (1200 MHz) on Ryzen2 we can only manage a 2% increase in bandwidth. This is why faster memory is needed.
Inter-Unit Latency – Same Core : Within the same core (sharing L1D/L2), Ryzen2 manages a 13% reduction in latency, again better than just clock speed increase.
Inter-Unit Latency – Same Compute Unit : Within the same compute unit (sharing L3), the latency decreased by 7% on Ryzen2 thus L3 seems to have improved also.
Inter-Unit Latency – Different Compute Unit : Going inter-CCX we still see a 6% reduction in latency on Ryzen2 – with the CCX link at the same speed – a welcome surprise.
The multiple CCX design still presents some challenges to programmers requiring threads to be carefully scheduled – but we see a decent 6-7% reduction in L3/CCX latencies on Ryzen2 even when running at the same clock as Ryzen1.
Aggregated L1D Bandwidth : Right off we see a 18% bandwidth increase – almost 2x higher (than the 11% clock increase) – thus some improvements have been made to the cache system. It allows Ryzen2 to finally beat the i7 with its wide L1 data paths (512-bit) though with twice as many (8 vs 4).
Aggregated L2 Bandwidth : We see a huge 32% increase in L2 cache bandwidth – almost 3x clock increase (the 11%) suggesting the L2 caches have been improved also. Ryzen2 has thus 2x the L2 bandwidth of i7 though with 2x more caches (8 vs 4).
Aggregated L3 Bandwidth : The bandwidth of the L3 caches has also increased by 19% (2x clock increase) though we see the 6-core 2600 doing better (398 vs 339) likely due to less threads competing for the same L3 caches. Ryzen2 L3 caches are not just 2x bigger than Intel but also 2x more bandwidth.
Aggregated Memory : With the same memory clock, Ryzen2 does still manage a small 2% improvement – signalling memory controller improvements. We also see Ryzen’s memory controller at 2400 having better bandwidth than Intel at 2533MHz.
We see big improvements on Ryzen2 for all caches L1D/L2/L3 of 20-30% – more than just raw clock increase (11%) – so AMD has indeed made improvements – which to be fair needed to be done. The memory controller is also a bit more efficient (2%) though it can run at higher clocks – hopefully fast DDR4 memory will become more affordable.
Data In-Page Random Latency : In-page latency has decreased by a noticeable 6% on Ryzen2 – we see 5 clocks reduction for L2 and 4 for L3 a welcome improvement. But still a way to go to catch Intel which has 1/3x (three times less) latency.
Data Full Random Latency : Out-of-page latencies have also been reduced by 8% on Ryzen2 (same memory) and we see the same 5 and 4 clock reduction for L2 and L3 (on both 2700X and 2600 thus no fluke). Again these are welcome but still have a way to go to catch Intel.
Data Sequential Latency : Ryzen’s prefetchers are working well with sequential access pattern latency and we see a 8% latency drop for Ryzen2.
Ryzen1’s issue was high memory latencies (in-page/full random) and Ryzen2 has reduced them all by 6-8%. While it is a good improvement, they are still pretty high compared to Intel’s thus more work needs to be done here.
Code In-Page Random Latency : Code latencies were not a problem on Ryzen1 but we still see a welcome reduction of 9% on Ryzen2.
Code Full Random Latency : Out-of-page latency also sees a 9% decrease on Ryzen2 but somewhat surprisingly a 1-2 clock increase.
Code Sequential Latency : Ryzen’s prefetchers are working well with sequential access pattern latency and we see a 8% reduction on Ryzen2.
While code access latencies were not a problem on Ryzen1 and they also see a 8% improvement on Ryzen2 which is welcome.
Memory Update Transactional : Ryzen2 is 10% faster than Ryzen1 but naturally without HLE support it cannot match the i7. But with Intel disabling HLE on all but top-end CPUs AMD does not have much to worry.
Memory Update Record Only : With only record updates we still see an 11% increase.
Ryzen2 brings nice updates – good bandwidth increases to all caches L1D/L2/L3 and also well-needed latency reduction for data (and code) accesses. Yes, there is still work to be done to bring the latencies down further – but it may be just enough to beat Intel to 2nd place for a good while.
At the high-end, ThreadRipper will likely benefit most as it’s going against many-core SKL-X AVX512-enabled competitor and we cannot wait to test those.
Final Thoughts & Conclusion On The Ryzen 7 2700X and Ryzen 5 2600
As with original Ryzen, the cache and memory system performance is not the clean-sweep we’ve seen in CPU testing – but Ryzen2 does bring welcome improvements in bandwidth and latency – which hopefully will further improve with firmware/BIOS updates.
With the potential to use faster DDR4 memory – Ryzen2 can do far better than in this test (e.g. with 3200MHz memory). Unfortunately at this time DDR4 – especially high-end fast versions – memory is hideously expensive which is a bit of a problem. You are better off using less but fast memory with Ryzen designs.
Ryzen2 is a great update that will not disappoint upgraders and is likely to increase AMD’s market share. AMD is here to stay!
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