Accelerating Fidelity CFD on AMD EPYC CPUs with AMD 3D V-Cache Technology

Computational fluid dynamics (CFD) applications are memory bandwidth-hungry, and Cadence Fidelity CFD software is no exception. From Fidelity Fine Turbo to Fidelity CharLES, the more memory bandwidth a processor has, the faster your simulation is going to run. AMD has once again knocked it out of the park with their 4^th Gen AMD EPYC^TM CPUs, which feature a best-in-class 12 channels of DDR5-4800. Compared to the previous generation AMD chips with eight channels of DDR4-3200, that means we would expect a server node with 4^th Gen AMD EPYC CPUs to run Fidelity solver technologies more than twice as fast as a similar node with previous-generation processors.

But that, of course, isn’t all. Since CFD easily consumes all the main memory bandwidth you can throw at it, technologies to increase the efficiency at which that bandwidth gets used have an outsize impact on CFD. A large L3 cache is especially useful to unstructured CFD since when you iterate through your mesh to build your fluxes, every value gets used multiple times, and the second read often doesn’t happen very close to the first. When this occurs, the value is no longer in the cache and must be reread from the comparatively slow main RAM once again.

With 2^nd Gen AMD EPYC processors, we saw the introduction of CPUs with a then-massive 128 MB max of L3 cache, which had visible effects on CFD performance. They upped the ante again with 3^rd Gen’s max of 256 MB, and shortly after 3^rd Gen’s release, AMD broke new ground with 3D die stacking, enabling 3^rd Gen AMD EPYC processors with AMD 3D V-Cache^TM technology to have 768 MB of L3 Cache. Across the CFD industry, the performance gains were substantial and obvious, and the response has been enthusiastic. I have been personally recommending 3^rd Gen AMD EPYC processors with AMD 3D V-Cache technology for CFD hardware whenever I get the chance.

The next generation is now here, and 4^th Gen AMD EPYC with AMD 3D V-Cache technology is delivering stunning performance gains. We benchmarked our Fidelity pressure-based solver technology on two different 4^th Gen AMD EPYC processors, the 9174F and 9814X, the second of which has an extra-large L3 cache. We found up to a 40% performance gain* across a variety of benchmarks run internally at Cadence, demonstrating that 4^th Gen AMD EPYC processors with AMD 3D V-Cache technology are an excellent choice for any HPC system built to run Fidelity CFD software.

Figure 1: 4^th Gen AMD EPYC processors with AMD 3D V-Cache technology enable up to 40% speedup in Fidelity CFD software over the baseline model.

AMD has once again delivered leadership-class performance for CFD users with the addition of AMD 3D V-Cache technology to their latest generation of processors. I’m thrilled to see the performance potential of these chips because I know CFD engineers who rely on Fidelity technology will do more work, better and faster than ever before. There are a wide variety of potential benefits: 40% faster means you can populate your Fidelity Fine Design3D design space with more points, leading to better optimizations. It means more time steps in your Fidelity Fine Marine seakeeping simulations for better predictions of how a ship responds to waves. It means a faster turnaround time for NLH simulations in Fidelity Fine Turbo, so you can analyze results, improve your design, and get to production faster. And if you have a large cluster, it can accelerate scale-resolving simulations with Fidelity CharLES, enabling deep investigation of fine flow structures and related phenomena. 

Figure 2: A combustion chamber optimized using Fidelity Fine Design3D. The speed of 4^th Gen AMD EPYC processors with AMD 3D V-Cache technology enables faster, more complete optimization runs

Cadence is accelerating CFD with our Fidelity CFD software family, and AMD 3D V-Cache^TM technology accelerates our software. Whether in a workstation or a cluster, I think Fidelity CFD users will be impressed by the performance.

*Testing performed internally by Cadence with no involvement from AMD 

For more information about AMD EPYC processors with 3D V-Cache technology, visit this page.