Sizing Things Up: Specifications Compared

Thirty-two high-IPC cores in one package sounds promising. But how does the best ThunderX2 compare to what AMD, Qualcomm and Intel have to offer? In the table below we compare the high level specifications of several top server SKUs.

Comparison of Major Server SKUs
AnandTech.com Cavium
ThunderX2
9980-2200
Qualcomm
Centriq 2460
Intel
Xeon 8176
Intel
Xeon 6148
AMD
EPYC 7601
Process Technology TSMC
16 nm
Samsung
10 nm
Intel
14 nm
Intel
14 nm
Global Foundries
14 nm
Cores 32
Ring bus
48
Ring bus
28
Mesh
20
Mesh
4 dies x 8 cores
MCM
Threads 128 48 56 40 64
Max. number of sockets 2 1 8 4 2
Base Frequency 2.2 GHz 2.2 GHz 2.2 GHz 2.4 GHz 2.2 GHz
Turbo Frequency 2.5 GHz 2.6 GHz 3.8 GHz 3.7 GHz 3.2 GHz
L3 Cache 32 MB 60 MB 38.5 MB 27.5 MB 8x8 MB
DRAM 8-Channel
DDR4-2667
6-Channel
DDR4-2667
6-Channel
DDR4-2667
6-Channel
DDR4-2667
8-Channel
DDR4-2667
PCIe 3.0 lanes 56 32 48 48 128
TDP 180W 120 W 165W 150W  180W
Price $1795 $1995 $8719 $3072 $4200

Astute readers will quickly remark that Intel's top of the line CPU is the Xeon Platinum 8180. However that SKU with its 205W TDP and $10k+ price tage is not comparable at all to any CPU in the list. We are already going out on a limb by including the 8176, which we feel belongs in this list of maximum core/thread count SKUs. In fact, as we will see further, Cavium positions the Cavium 9980 as "comparable" to the Xeon Platinum 8164, which is essentially the same part as the 8176 but with slightly lower clockspeeds.

However, it terms of performance per dollar, Cavium typically compares their flagship 9980 to the Intel Xeon Gold 6148, against which the pricing of Cavium's CPU is very aggressive. Many of Cavium's benchmarks claim that the fastest ThunderX2 is 30% to 40% ahead of the Xeon 6148, all the while Cavium's offering comes in at $1300 less. That aggressive pricing might explain the increasingly persistent rumors that Qualcomm is not going to enter the server market after all.

When looking at the table above, you can already see some important differences between the contenders. Intel seems to have the most advanced core topology and the highest turbo clockspeed. Meanwhile Qualcomm has the best chances when it comes to performance per watt, and has already published some benchmarking data that underlines this advantage.

Similar to AMD's EPYC, Cavium's ThunderX2 is likely to shine in the "sparse matrix" HPC market. This is thanks to its 33% greater theoretical memory bandwidth and a high core/thread count. However as we've seen in the case of AMD's design, EPYC's L3-cache is slow once you need data that is not in the local 8 MB cache slice. The ThunderX2, by comparison, is a lot more sophisticated with a dual ring architecture, which seems to be similar to the ring architecture of the Xeon v4 (Broadwell-EP). According to Cavium, this ring structure is able to offer up to 6 TB/s of bandwidth and is non-blocking.

This ring architecture is connected to Cavium's Coherent Processor Interconnect (CCPI2 - at the top of the picture), which runs at 600 Gb/sec. This interconnect links the two sockets/NUMA nodes. Also connected to the ring are the SoC's 56 PCIe 3.0 lanes, which Cavium allocates among 14 PCIe "controllers.". These 14 controllers can, in turn, be bifurcated down to x4 or x1 as you can see below.

SR-IOV, which is important for I/O virtualization (Xen and KVM), is also supported.

ThunderX2: Cavium Is Back Cavium's "New" Core: Vulcan
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  • JohanAnandtech - Thursday, May 24, 2018 - link

    I have been trouble shooting a Java problem for the last 3 weeks now - for some reason our specific EPYC test system has some serious performance issues after we upgraded to kernel 4.13. This might be a hardware/firmware... issue. I don't know. I just know that the current tests are not accurate. Reply
  • npz - Thursday, May 24, 2018 - link

    Large Pages should be used whenever possible on Intel. You do waste some more memory, but it's worth it for most workloads as can be seen in your Intel Java benchmark. We've tested it for IO devices and enabling large pages in drivers to do DMA to shows a big difference for some high throughput devices. Reply
  • junky77 - Thursday, May 24, 2018 - link

    What? A 2.5GHZ ARM core is around 60-70% of a 3.8GHZ Skylake core?? For 3.8GHZ, the ARM is probably at least as fast? Reply
  • Wilco1 - Thursday, May 24, 2018 - link

    Probably around 90% since performance doesn't scale linearly with frequency. Note these are throughput parts so won't clock that high. However a 7nm version might well reach 3GHz. Reply
  • AJ_NEWMAN - Thursday, May 24, 2018 - link

    If Caviums tweaked 16nm hits 3GHz - it would to be unreasonable to aim for 4GHz for a 7nm part.

    With 2.3 times as many transistors available - it will be interesting to see what else they beef up?

    HIgher IPC? 64 cores? 16 memory controllers? CCIX - or perhaps they will compete with Fujitsu and add some Supercomputer centric hardware?

    AJ
    Reply
  • meta.x.gdb - Thursday, May 31, 2018 - link

    Wonder why the VASP code limped along on ThunderX2 while OpenFOAM saw such gains. I'm pretty familiar with both codes. VASP is mostly doing density functional theory, which is FFT-heavy... Reply
  • Meteor2 - Tuesday, June 26, 2018 - link

    All I want to say (all I can say) is that Anandtech has some of the best writers and commenters in this field. Fantastic article, and fantastic discussion. Reply
  • paldU - Saturday, July 7, 2018 - link

    A typo in Page 2. "it terms of performance per dollar" should be " in terms of performance per dollar". Reply

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