A little less than 2 years ago, we investigated the first Arm server SoC that had a chance to compete with midrange Xeon E5s: the Cavium ThunderX. The SoC showed promise, however the low single-threaded performance and some power management issues relegated the 48-core SoC to more niche markets such as CDN and Web caching. In the end, Cavium's first server SoC was not a real threat to Intel's Xeon.

But Cavium did not give up, and rightfully so: the server market is more attractive than ever. Intel's datacenter group is good for about 20 Billion USD (!) in revenue per year. And even better, profit margins are in 50% range. When you want to profits and cash flow, the server market far outpaces any other hardware market. So following the launch of the ThunderX, Cavium promised to bring out a second iteration: better power management, better single thread performance and even more cores (54).

The trick, of course, is actually getting to a point where you can take on the well-oiled machine that is Intel. Arm, Calxeda, Broadcom, AppliedMicro and many others have made many bold promises over the past 5 years that have never materialized, so there is a great deal of skepticism – and rightfully so – towards new Arm Server SoCs.

However, the new creation of underdog Cavium deserves the benefit of the doubt. Much has changed – much more than the name alone lets on – as Cavium has bought the "Vulcan" design from Avago. Vulcan is a rather ambitious CPU design which was originally designed by the Arm server SoC team of Broadcom, and as a result has a much different heritage than the original ThunderX. At the same time however, based on its experience from the ThunderX, Cavium was able to take what they've learned thus far and have introduced some microarchitectural improvements to the Vulcan design to improve its performance and power.

As a result, ThunderX2 is a much more "brainiac" core than the previous generation. While the ThunderX core had a very short pipeline and could hardly sustain 2 instructions per clock, the Vulcan core was designed to fetch 8 and execute up to 4 instructions per clock. It gets better: 4 simultaneous threads can be active (SMT4), ensuring that the wide back-end is busy most of the time. 32 of those cores at clockspeeds up to 2.5 GHz find a home in the new ThunderX2 SoC.

With up to 128 threads running and no less than eight DDR4 controllers, this CPU should be able to perform well in all server situations. In other words, while the ThunderX (1) was relegated to niche roles, the ThunderX2 is the first Arm server CPU that has a chance to break the server market open.

Sizing Things Up: Specifications Compared
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  • Gunbuster - Wednesday, May 23, 2018 - link

    Because it's hard to explain the critical line of business software or database is having some unknown edge case issue because you thought look at me I'm so smart and saved 1% of the project cost using unproven low penetration hardware.
  • daanno2 - Wednesday, May 23, 2018 - link

    I'm guessing you've never dealt with expensive enterprise software before. They are mostly licensed per-core, so getting the absolute best performance per core, even if the CPU is 2-3x more expensive, is worth it. At the end of the day, the CPUs might be <5% of the total cost.
  • SirPerro - Wednesday, May 23, 2018 - link

    You can swallow a big risk if the benefit is 75% of the cost. Hey, it's definitely worth the try.

    If your hardware makes up for 5% of the cost, saving a 3% of the total budget is not worth the risk of migration.
  • FunBunny2 - Thursday, May 24, 2018 - link

    "You can swallow a big risk if the benefit is 75% of the cost. Hey, it's definitely worth the try."

    the EOL of today's machines, the amortization schedules must be draconian. only if a 'different' server pays off in dozens of months, not years, will it have chance. to the extent that enterprise software is a C/C++ and *nix codebase, porting won't be onerous. but, I'm willing to guess, even Oracle code isn't all that parallel, so throwing a truckload of teeny cpu at it won't necessarily work.
  • name99 - Thursday, May 24, 2018 - link

    The bigger problem here is the massive uncertainty around the meaning of the word "server" and thus the target for these new ARM CPUs.
    Some people seem to think "server" means primarily boxes that run SAP or ORACLE, but I think it's clear that the ARM ecosystem has little interest in that, at least right now.

    What's of much more interest is racks on racks of CPUs running commodity (LAMP) or homegrown software, ie data warehouses and HPC. I'm not even sure the Java benchmarks being run are of much interest to this market. The things that matter are the sorts of things Cloudflare was measuring when they tested Centriq -- memcached, nginx, transforming one type of data into another (compression/decompression, encrypt/decrypt, transcode,...) at massive throughput.
    That's where I'd expect to see the big sales of the ARM "server" cores -- to Cloudflare, Baidu, Google, and so on.

    Also now that Marvell is in the game, will be interesting to see the extent to which they pull this downward, into their traditional sorts of markets like infrastructure network and storage control (eg to go into network appliances and NAS boxes).
  • Ed469546 - Wednesday, June 13, 2018 - link

    Some of the commercial software you pay per core. Intel had the best single threaded performance mening power license costs.

    Interesting question is how the Thunderx2 cores are counted in this case: one core can run 4 threads.
  • andrewaggb - Wednesday, May 23, 2018 - link

    I wonder what workloads they are targeting? High throughput with poor single threaded results is somewhat limiting.
  • peevee - Wednesday, May 23, 2018 - link

    Web app servers. VM servers. Hadoop/Spark nodes. All benefit more from having more threads running in parallel instead of each request waiting or switching contexts.

    If you are concerned about single-thread performance on 256-thread server (as 2-CPU server with this CPU will provide) AT ALL, you choose outrageously wrong hardware for the task to begin with. Go buy a 2-core i3. Practically the only test in this article which matters is Critical jOPS (assuming the used quality of service metric was configured realistically).
  • GeekyMcGeekface - Friday, May 25, 2018 - link

    I’m building a cluster now with a few hundred Raspberry Pi’s because scale up is expensive and stupid. By distributing across a pool of clusters, I can handle far more memory bandwidth and compute. Consider 100 Raspberry PIs have 400 64-bit cores and 100GB of RAM. Total cost $3500 + power, mounting and switches.

    Running three clusters of those with Kubernetes, Couchbase and Azure Functions provides 1200 64-bit cores, about 100GB of extremely high performance storage, incredible failover and a map-reduce environment to die for.

    Add some 64GB MicroSD cards and an object storage system to the cluster and there’s 12TB of cold storage (4TB when made redundant).

    Pay a service fee to some sweatshop in the Eastern Block to do the labor intensive bits and you can build a massively parallel, almost impossible to crash, CI/CD friendly, multi-tenant, infinitely scalable PaaS... for less than the cost of the RAM for a single one of the servers here.

    The only expensive bits in the design are the Netscalers.

    Oh... and the power foot print is about the same as one of these servers.

    I honestly have no idea what I what I would use a server like these in a new design for.
  • jospoortvliet - Wednesday, May 30, 2018 - link

    single-core performance with your pi's is considerably lower, as is inter-core bandwidth. If your tasks require little inter-process communication you're good but with highly interdependent compute it won't perform well. But for specific tasks, yes, it might be very cost effective.

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