Intel Core i9 9900K CofeeLake-R Review & Benchmarks – 2-channel DDR4 Cache & Memory Performance

What is “CofeeLake-R” CFL-R?

It is the “refresh” (updated) version of the 8th generation Intel Core architecture (CFL) – itself a minor stepping of the previous 7th generation “KabyLake” (KBL), itself a minor update of the 6th generation “SkyLake” (SKL). While ordinarily this would not be much of an event – this time we do have more significant changes:

  • Patched vulnerabilities in hardware: this can help restore I/O workload performance degradation due to OS mitigations
    • Kernel Page Table Isolation (KPTI) aka “Meltdown” – Patched in hardware
    • L1TF/Foreshadow – Patched in hardware
    • (IBPB/IBRS) “Spectre 2” – OS mitigation needed
    • Speculative Store Bypass disabling (SSBD) “Spectre 4” – OS mitigation needed
  • Increased core counts yet again: CFL-R top-end now has 8 cores, not 6.

Intel CPUs bore the brunt of the vulnerabilities disclosed at the start of 2018 with “Meltdown” operating system mitigations (KVA) likely having the biggest performance impact in I/O workloads. While modern features (e.g. PCID (process context id) acceleration) could help reduce performance impact somewhat on recent architectures (4th gen and newer) the impact can still be significant. The CFL-R hardware fixes (thus not needing KVA) may thus prove very important.

On the desktop we also see increased cores (again!) now up to 8 (thus 16 threads with HyperThreading) – double what KBL and SKL brought and matching AMD.

We also see increased clocks, mainly Turbo, but this still allows 1 or 2 cores to boost clocks higher than CFL could and thus help workloads not massively threaded. This can improve responsiveness as single tasks can be run at top speed when there is little thread utilization.

While rated TDP has not changed, in practice we are likely to see increased “real” power consumption especially due to higher clocks – with Turbo pushing power consumption even higher – close to SKL/KBL-X.

In this article we test CPU Core performance; please see our other articles on:

Hardware Specifications

We are comparing the top-of-the-range Gen 8 Core i7 (8700K) with previous generation (6700K) and competing architectures with a view to upgrading to a mid-range high performance design.

CPU Specifications Intel i9-9900K CofeeLake-R Intel i7-8700K CofeeLake AMD Ryzen2 2700X Pinnacle Ridge Intel i9-7900X SkyLake-X Comments
L1D / L1I Caches 8x 32kB 8-way / 8x 32kB 8-way 6x 32kB 8-way / 6x 32kB 8-way 8x 32kB 8-way / 8x 64kB 8-way 10x 32kB 8-way / 10x 32kB 8-way No L1D/I changes, Ryzen’s L1I is twice as big.
L2 Caches 8x 256kB 4-way 6x 256kB 4-way 8x 512kB 8-way 10x 1MB 16-way No L2 changes, Ryzen’s L2 is twice as big again.
L3 Caches 16MB 16-way 12MB 16-way 2x 8MB 16-way 2x 8MB 16-way L3 has also increased with no of cores, and now matches Ryzen.
TLB 4kB pages
64 4-way / 64 8-way / 1536 6-way 64 4-way / 64 8-way/ 1536 6-way 64 full-way 1536 8-way 64 4-way / 64 8-way / 1536 6-way No TLB changes.
TLB 2MB pages
8 full-way / 1536 6-way 8 full-way / 1536 6-way 64 full-way 1536 2-way 8 full-way / 1536 6-way No TLB changes.
Memory Controller Speed (MHz) 1200-5000 1200-4400 1333-2667 1200-2700 The uncore (memory controller) runs at faster clock due to higher rated clock but not a lot in it.
Memory Data Speed (MHz)
3200 3200 2667 3200 CFL/R can easily run at 3200Mt/s while KBL/SKL were not as reliable. We could not get Ryzen past 2667 while it does support 2933.
Memory Channels / Width
2 / 128-bit 2 / 128-bit 2 / 128-bit 2 / 128-bit All have 128-bit total channel width.
Memory Bandwidth (GB/s)
50 50 42 100 Bandwidth has naturally increased with memory clock speed but latencies are higher.
Uncore / Memory Controller Firmware
2.6.2 2.6.2 We’re on firmware 2.6.x on both.
Memory Timing (clocks)
16-16-16-36 6-52-25-12 2T 16-16-16-36 6-52-25-12 2T 16-17-17-35 7-60-20-10 2T Timings are very much BIOS dependent and vary a lot.

Native Performance

We are testing native arithmetic, SIMD and cryptography performance using the highest performing instruction sets (AVX2, AVX, etc.). CFL-R supports most modern instruction sets (AVX2, FMA3) but not the latest SKL/KBL-X AVX512 nor a few others like SHA HWA (Atom, Ryzen).

Results Interpretation: Higher values (GOPS, MB/s, etc.) mean better performance.

Environment: Windows 10 x64 (1807), latest drivers. 2MB “large pages” were enabled and in use. Turbo / Boost was enabled on all configurations.

Spectre / Meltdown Windows Mitigations: all were enabled as per default (BTI enabled, RDCL/KVA enabled, PCID enabled).

Native Benchmarks Intel i9-9900K CofeeLake-R Intel i7-8700K CofeeLake AMD Ryzen2 2700X Pinnacle Ridge Intel i9-7900X SkyLake-X Comments
CPU Multi-Core Benchmark Total Inter-Core Bandwidth – Best (GB/s) 70.7 [+28%] 52.5 55.3 86 CFL-R finally overtakes Ryzen2 in inter-core bandwidth with almost 30% more bandwidth.
CPU Multi-Core Benchmark Total Inter-Core Bandwidth – Worst (GB/s) 15.4 [-1%] 15.5 6.35 25.7 In worst-case pairs on Ryzen2 must go across CCXes – unlike Intel’s CPUs – thus CFL can muster over 2x more bandwidth in this case.
CFL-R manages good bandwidth improvement with its 2  extra cores allowing it to dominate Ryzen  2; worst-case bandwidth does not improve as the inter-core connector has remained the same
CPU Multi-Core Benchmark Inter-Unit Latency – Same Core (ns) 13.4 [-7%] 14.4 13.5 15 With its faster clock, CFL-R manages lower inter-core latency with 7% drop.
CPU Multi-Core Benchmark Inter-Unit Latency – Same Compute Unit (ns) 43.7 [-3%] 45 40 75 Within the same unit, Ryzen2 is again faster than CFL/R.
CPU Multi-Core Benchmark Inter-Unit Latency – Different Compute Unit (ns) 115 Obviously going across CCXes is slow, about 3x slower which needs careful thread scheduling.
The multiple CCX designof Ryzen 2 still presents some challenges to programmers requiring threads to be carefully scheduled – thus the unified CFL-R just like CFL before it enjoys lower latencies throughout.
Aggregated L1D Bandwidth (GB/s) 1890 [+39%] 1630
854 2220 Intel’s wide L1D in CFL/R means almost 2x more bandwidth than Ryzen 2.
Aggregated L2 Bandwidth (GB/s) 618 [+8%] 571 720 985 But Ryzen2’s L2 caches are not only twice as big but also very wide – CFL/R surprisingly cannot beat it.
Aggregated L3 Bandwidth (GB/s) 326 [=] 327 339 464 Ryzen’s 2 L3 caches also provide good bandwidth matching CFL’s unified L3 cache.
Aggregated Memory (GB/s) 35.5 [=] 35.6 32.2 70 Running at 3200Mt’s obviously CFL enjoys higher bandwidth than Ryzen2 at 2667Mt’s but somehow the latter has better efficiency.
Nothing much has changed in CFL/R vs. old SKL/KBL thus while L1 caches are wide and thus fast – the L2, L3 are not as impressive and the memory controller while competitive it does not seem as efficient as Ryzen2 but is more stable at high data rates allowing for higher bandwidth.
Data In-Page Random Latency (ns) 17.5 (3-10-21) 17.4 (4-11-20) [-73%] 63.4 (4-12-31) 25.5 (4-13-30) While clock latencies have not changed w.s. old KBL/SKL, CFLR enjoys lower latencies due to higher data rates. Ryzen2 has problems here.
Data Full Random Latency (ns) 54.3 (3-10-36) 53.4 (4-11-42) [-30%] 76.2 (4-12-32) 74 (4-13-62) Out-of-page clock latencies have increased but still overall lower. Ryzen2 has almost caught up here.
Data Sequential Latency (ns) 3.8 (3-10-11) 3.8 (4-11-12) 3.3 (4-6-7) 5.3 (4-12-12) With sequential access, Ryzen2 is now faster as CFL/R’s clock latencies have not changed.
CFL-R does not improve over CFL (same memory controller) is lucky here as even Ryzen2 still has high latencies in random accesses (either in-page or full range) but manages to be faster with sequential access. Intel will need to improve going forward as clock latencies while good have really not improved at all.
Code In-Page Random Latency (ns) 8.6 (2-9-19) 8.7 (2-10-21) 13.8 (4-9-24) 11.8 (4-14-25) Code clock latencies also have not changed and again and while Ryzen2 performs a lot better, CFL/R manage to be ~35% faster.
Code Full Random Latency (ns) 60.1 (2-9-48) 59.8 (2-10-48) 85.7 (4-14-49) 83.6 (4-15-74) Out-of-page clock latencies also have not changed and here CFL/R is 20% faster over Ryzen2.
Code Sequential Latency (ns) 4.3 (2-3-8) 4.5 (2-4-10) 7.4 (4-12-20) 6.8 (4-7-11) Ryzen2 is competitive but again CFL/R manages to be almost 40% faster.
CFL/R does not improve over CFL but still dominates here and enjoys 30-40% less latency over Ryzen2 but the latter has improved a lot in time.
Memory Update Transactional (MTPS) 73.3 [+36%] 54 5 59 Finally all top-end Intel CPUs have HLE enabled and working and thus enjoy huge performance increase.
Memory Update Record Only (MTPS) 53.4 [+41%] 38 4.58 59 Nothing much changes here. CFL-R can do over 40% more transactions.

CFL-R does not really perform any different cache/memory wise vs. old CFL as the caches and memory controller are unchanged.

SiSoftware Official Ranker Scores

Final Thoughts / Conclusions

CFL-R just adds more cores, thus enjoys higher aggregated L1D/L2 bandiwdths vs CFL but the L3 is still disappointing – especially as now it has to feed 33% more cores/threads (8/16 vs 6/12). Latencies (in clocks) do not change either but as it can clock higher they do decrease in real terms (ns).

The memory controller is the very same (even running same firmware) thus performs the same though now it has to feed 33% more cores/threads (8/16 vs 6/12) thus when all cores/threads are used the aggregated bandwidth falls due to extra contention. In fairness Ryzen2 has the same issue (too many cores/threads for too little bandwidth) thus SKL/KBL-X is where you should be looking for more bandwidth.

SiSoftware Sandra Titanium (2018) SP4/a Update: Retpoline and hardware support

We are pleased to release SP4/a (Service Pack 4/a – version 28.61) update for Sandra Titanium (2018) with the following updates:

Sandra Titanium (2018) Press Release

  • Reporting of Operating System (Windows) speculation control settings for the recently discovered vulnerabilities:
    • Kernel Retpoline mitigation status in recent Windows 10 / Server 2019 updates
    • Kernel Address Table Import Optimisation status (as above)
    • L1TF – L1 data terminal fault mitigation status
  • Hardware Support:
    • AMD Ryzen2 (Matisse), Stoney Ridge support
    • Intel CometLake (CML), CannonLake (CNL), IceLake (ICL) support (based on public information)
  • CPU Benchmarks:
    • Image Processing: SIMD code improvement (SSE2/SSE4/AVX/AVX2-FMA/AVX512)
  • Memory/Cache Benchmarks
    • Return memory controller firmware version to Ranker
  • GPGPU Benchmarks:
    • CUDA SDK 10.1
    • OpenCL: Processing (Fractals/Mandelbrot) variable vector width based on reported FP16/32/64 optimal SIMD width.
  • Ranker, Price & Information Engines
    • HTTPS (encryption) support for all engines as well as the main website

What is Retpoline?

It is a mitigation against ‘Spectre‘ 2 variant (BTI – Branch Target Injection) that affects just about all CPUs (not just Intel but AMD, ARM, etc.). While ‘Spectre’ does not have the same overall performance impact degradation as ‘Meltdown‘ (RDCL – Rogue Data Cache Load) it can have a sizeable impact on some processors and workloads. At this time no CPUs contain hardware mitigation for Spectre without performance impact.

Retpoline (Return Trampoline) is a faster way to mitigate against it without restricting branch speculation in kernel mode (using IBRS/IBPB) and has recently been added to Linux and now Windows version 1809 builds with KB4482887. Note that it still needs to be enabled in registry via the Mitigation Features Override flags as by default it is not enabled.

What CPUs can Retpoline be used on?

Unfortunately Retpoline is only safe to use on some CPUs: AMD CPUs (though does not engage on Ryzen, see below), Intel Broadwell or older (v5 and earlier) – thus not Skylake (v6 or later).

Windows speculation control settings reporting:

Intel Haswell (Core v4), Broadwell (v5) – Retpoline enabled, KATI enabled
Kernel Retpoline Speculation Control – Enabled

Kernel Address Table Import Optimisation – Enabled

(Note RDCL mitigations KVA, L1TF are also enabled as required)

Intel Skylake (Core v6), Kabylake (v7), Skylake/Kabylake-X (v6x) – no Retpoline, KATI can be enabled
Kernel Retpoline Speculation Control – no

Kernel Address Table Import Optimisation – no/yes (can be enabled)

(Note RDCL mitigations KVA, L1TF are enabled as required)

Intel Coffeelake-R (Core v8r), Whiskeylake/AmberLake (Core v8r), CometLake* – no Retpoline but KATI enabled
Kernel Retpoline Speculation Control – no

Kernel Address Table Import Optimisation – Enabled

(Note CPU does not require RDCL mitigation thus no KVA, L1TF required)

Intel Atom Braswell (Atom v5), GeminiLake/ApolloLake (Atom v6) – no Retpoline but KATI enabled
Kernel Retpoline Speculation Control – no

Kernel Address Table Import Optimisation – Enabled

(Note RDCL mitigations KVA, L1TF are enabled as required)

AMD Ryzen (Threadripper) 1, 2 – no Retpoline, no KATI
Kernel Retpoline Speculation Control – no (should be usable?)

Kernel Address Table Import Optimisation – no (should be usable)

(Note CPU does not require RDCL mitigation thus no KVA, L1TF required)

From our somewhat limited testing above it seems that:

  • Intel Haswell/Broadwell (Core v4/v5) and perhaps earlier (Ivy Bridge/Sandy Bridge Core v3/v2) users are in luck, Retpoline is enabled and should improve performance; unfortunately KVA (Meltdown mitigation) remains.
  • Intel Coffeelake-R (Core v8r refresh), Whiskylake ULV (v8r) users do benefit a bit more for their investment – while Retpoline is not enabled, KATI is enabled and should help. Not requiring KVA is the biggest gain of CFL-R.
  • Intel Skylake (Core v6), Kabylake (v7) and Coffeelake (v8) are not able to benefit from Retpoline but KATI can work on some systems (driver dependent). However, on our Skylake ULV, Skylake-X test systems KATI could not be enabled. We are investigating further.
  • Intel Atom (v4/v5+) users should be able to use Retpoline but it seems it cannot be enabled currently. KATI is enabled.
  • AMD Ryzen (Threadripper) 1, 2 users should also be able to use Retpoline but it seems it cannot be enabled currently. While KVA is not required, mitigations for Spectre v2 are required and should be enabled. We are investigating further.

Commercial version customers can download the free updates from their software distributor; Lite users please download from your favourite download site.

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