Category: Hardware

Glenn Berry takes a look at whether we want to invest in AMD’s latest server-grade processor:

On August 7, 2019, AMD finally unveiled their new 7nm EPYC 7002 Series of server processors, formerly code-named “Rome” at the AMD EPYC Horizon Event in San Francisco. This is the second generation EPYC server processor that uses the same Zen 2 architecture as the AMD Ryzen 3000 Series desktop processors. These new processors are socket compatible with the previous generation AMD EPYC 7001 Series processors, so they will work in existing model servers (with a BIOS update). Despite that, you will need a new model server to be able to use PCIe 4.0 support from the newer processors.

The AMD EPYC 7002 series includes 19 public launch SKUs that have anywhere from 8 to 64 physical cores, plus SMT, for twice the number of logical cores per processor. There are fourteen SKUs that will work in both one-socket and two-socket servers. There are also five less expensive processor SKUs (which have a “P” suffix) that only work in one-socket servers. This processor family has enough compute horsepower, memory bandwidth and capacity, and I/O bandwidth to support large server workloads on a single-socket server.

It certainly looks competitive. And that’s a great thing for consumers, even those who never make the switch, as it will force Intel to up its game.

Glenn Berry has an interesting post on why he’s seriously considering recommending AMD CPUs to people:

AMD claims a 15% Instructions Per Clock (IPC) increase between the desktop Zen+ and Zen 2 generations, and we are likely to see a similar increase between the previous AMD EPYC 7001 “Naples” and the AMD EPYC 7002 series processors.

So far, we don’t know the official base and turbo clock speeds, but there was a recent leak of partial specifications and pricing by a European retailer that listed max boost clock speeds of up to 3.4 GHz. We won’t know the actual single-threaded performance of these processors until they have been released and benchmarked by neutral third-party testers. I am optimistic that they will have higher single-threaded CPU performance than Intel Cascade Lake-SP processors.

I’ve always had a soft spot in my heart for AMD, so I’d love to see them come through with a serious competitor to Intel in the server space, for nostalgic reasons but also to make price more competitive and to make Intel get back on its game.

Joe Chang thinks about single-socket servers:

There is a mechanism by which we can significantly influence memory latency in a multi-processor (socket) server system, that being memory locality. But few applications actually make use of the NUMA APIs in this regard. Some hypervisors like VMware allow VMs to be created with cores and memory from the same node. What may not be appreciated, however, is that even local node memory on a multi-processor system has significantly higher latency than memory access on a (physical) single-socket system.

That the single processor system has low memory latency was interesting but non-actionable bit of knowledge, until recently. The widespread practice in IT world was to have the 2-way system as the baseline standard. Single socket systems were relegated to small business and turnkey solutions. From long ago to a few years ago, there was a valid basis for this, though the reasons changed over the years. When multi-core processors began to appear, the 2-way became much more powerful than necessary for many secondary applications. But this was also the time virtualization became popular, which gave new reason to continue the 2-way as baseline practice.

Joe points out that for a highly-used transactional system, the lower memory latency might make a single-socket server perform better than a multi-socket server.

Joe Chang wants us to think about socket counts:

It might seem that the 2-socket system continues to be a good choice, as two processors with an intermediate number of cores is less expensive than one processor with twice as many cores. An example is the Xeon Gold 6132 14-core versus the Xeon Platinum 8180 28-core processors. In addition, the two-socket system has twice the memory capacity and nominally twice as much memory bandwidth.

So, end of argument, right? Well, no.

Click through for his argument in favor of single-socket machines for OLTP systems.

Glenn Berry talks about the new AMD processor lines and how they might work with SQL Server:

AMD is really pushing the idea of a single-socket EPYC system as a better alternative to a two-socket Intel system for many server workloads. According to AMD, it will be much less expensive, yet will have plenty of cores, memory, and PCIe 3.0 lanes, along with no NUMA overhead. One key advantage AMD is touting is their Infinity Fabric modular interconnect technology, that works both within a single processor and between multiple processors.

For SQL Server 2016/2017 usage, you would still want the “top of the line” SKU for a given physical core count, to get the most performance for each physical core license that you buy. Unlike Intel, AMD does not increase the base clock speed in the lower core count models. These EPYC systems have a lot of PCIe 3.0 lanes and very high memory density, so they might work really well for large SQL Server DW/Reporting workloads. For OLTP workloads, the key will be how much single-threaded performance AMD is able to get from this first-generation of EPYC, and how they compare to Intel’s new Skylake-SP processors. Figure 3 shows the fastest EPYC processor at each core count, which is what you would want for SQL Server usage.

There aren’t too many hard numbers yet, but the worst case scenario is that they force Intel to improve their offerings.