June 17, 2024


Improved MPI efficiency interprets on to improved software scaling, increasing the set of workloads that run effectively on Google Cloud. In case you plan to run MPI workloads on Google Cloud, use these practices to get the very best efficiency. Quickly, it is possible for you to to make use of the upcoming HPC VM Picture to simply apply these greatest practices and get the perfect out-of-the-box efficiency to your MPI workloads on Google Cloud.

1. Use Compute-optimized VMs

Compute-optimized (C2) cases have a hard and fast virtual-to-physical core mapping and expose NUMA structure to the visitor OS. These options are vital for efficiency of MPI workloads. Additionally they leverage second Era Intel Xeon Scalable Processors (Cascade Lake), which may present as much as a 40% enchancment in efficiency in comparison with earlier era occasion varieties because of their assist for a better clock pace of three.eight GHz, and better reminiscence bandwidth. 

C2 VMs additionally assist vector directions (AVX2, AVX512). We now have observed important efficiency enchancment for a lot of HPC purposes when they’re compiled with AVX directions. 

2. Use compact placement coverage 

A placement coverage offers you extra management over the location of your digital machines inside a knowledge middle. A compact placement coverage ensures cases are hosted in nodes close by on the community, offering decrease latency topologies for digital machines inside a single availability zone. Placement coverage APIs at present permit creation of as much as 22 C2 VMs.

three. Use Intel MPI and collective communication tunings

For the perfect MPI software efficiency on Google Cloud, we advocate the usage of Intel MPI 2018. The selection of MPI collective algorithms can have a major impression on MPI software efficiency and Intel MPI means that you can manually specify the algorithms and configuration parameters for collective communication. 

This tuning is completed utilizing mpitune and must be performed for every mixture of the variety of VMs and the variety of processes per VM on C2-Normal-60 VMs with compact placement insurance policies. Since this takes a substantial period of time, we offer the really useful Intel MPI collective algorithms to make use of in the commonest MPI job configurations.

For higher efficiency of scientific computations, we additionally advocate use of Intel Math Kernel Library (MKL).

four. Regulate Linux TCP settings

MPI networking efficiency is vital for tightly coupled purposes through which MPI processes on completely different nodes talk often or with massive information quantity. You may tune these community settings for optimum MPI efficiency.

5. System optimizations

Disable Hyper-Threading
For compute-bound jobs through which each digital cores are compute sure, Intel Hyper-Threading can hinder total software efficiency and might add nondeterministic variance to jobs. Turning off Hyper-Threading permits extra predictable efficiency and might lower job instances. 

Overview safety settings
You may additional enhance MPI efficiency by disabling some built-in Linux safety features. If you’re assured that your programs are nicely protected, you may consider disabling the next safety features as described in Safety settings part of the perfect practices information:

Now let’s measure the impression  

On this part we display the impression of making use of these greatest practices by way of application-level benchmarks by evaluating the runtime with choose clients’ on-prem setups: 

(i) Nationwide Oceanic and Atmospheric Administration (NOAA) FV3GFS benchmarks

We measured the impression of the perfect practices by operating the NOAA FV3GFS benchmarks with the C768 mannequin and 104 C2-Normal-60 Situations (three,120 bodily cores). The anticipated runtime goal, primarily based on on-premise supercomputers, was 600 seconds. Making use of these greatest practices supplied a 57% enchancment in comparison with baseline measurements—we have been in a position to run the benchmark in 569 seconds on Google Cloud (quicker than the on-prem supercomputer).


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