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Supercomputers? I've done work on 192-core machines in the past doing MPI jobs.

by physicsguy 2y ago

bee_rider 2y ago
It is crazy how few MPI processes it takes to get to 1000 cores now, haha.
- highfrequency 2y ago
  What is MPI?
  - bee_rider 2y ago
    Message Passing Interface. It is a very popular API for distributed computing, particularly in the scientific computing/hpc world.
  - dorfsmay 2y ago
    https://en.wikipedia.org/wiki/Message_Passing_Interface https://en.wikipedia.org/wiki/Message_Passing_Interface
  - porcoda 2y ago
    Distributed memory parallel computing library. Most common in supercomputers with a high performance interconnect where you want to run one program that coordinates separate instances of itself via message passing (“SPMD” - single program multiple data parallelism). Slightly different than distributed computing that generally doesn’t assume a tightly coupled system with a low latency, high bandwidth interconnect. Allows you to scale up beyond what you can do within shared memory spaces where you are limited to low core counts (hundreds) and low memory (<1TB) - MPI is what you use when you’re in the many thousands of cores, many TB of RAM regime. In practice, supercomputers require a mixture: shared memory for many core parallelism, some hybrid host programming model for bringing accelerators in, and then MPI to coordinate between these shared memory/accelerator enabled hosts.
CaliforniaKarl 2y ago
Supercomputers, yes, but also genomics workloads. The vast majority of those workloads are effectively tied to one machine, since they don’t support cross-machine scaling, nor things like MPI.
- Jtsummers 2y ago
  Do they not support MPI and scaling across machines because of the features of the workloads or because of the features of the systems performing the work? If the latter, then maybe they can use multiple cores using things like OpenMP and the like to get some "free" scaling, but they could be made to work with MPI or across machines. However, if it's the former, more cores won't help them.
NGRhodes 2y ago
As a fresh example, we (a University) have just this month had delivered about 9000 cores (and about 80 GPUs) of machines, these are being added to our existing 6000 cores (approx 5 year old) machines. This is a modest HPC system.

Supercomputers? I've done work on 192-core machines in the past doing MPI jobs.

bee_rider 2y ago

It is crazy how few MPI processes it takes to get to 1000 cores now, haha.

highfrequency 2y ago
What is MPI?
- bee_rider 2y ago
  Message Passing Interface. It is a very popular API for distributed computing, particularly in the scientific computing/hpc world.
- dorfsmay 2y ago
  https://en.wikipedia.org/wiki/Message_Passing_Interface https://en.wikipedia.org/wiki/Message_Passing_Interface
- porcoda 2y ago
  Distributed memory parallel computing library. Most common in supercomputers with a high performance interconnect where you want to run one program that coordinates separate instances of itself via message passing (“SPMD” - single program multiple data parallelism). Slightly different than distributed computing that generally doesn’t assume a tightly coupled system with a low latency, high bandwidth interconnect. Allows you to scale up beyond what you can do within shared memory spaces where you are limited to low core counts (hundreds) and low memory (<1TB) - MPI is what you use when you’re in the many thousands of cores, many TB of RAM regime. In practice, supercomputers require a mixture: shared memory for many core parallelism, some hybrid host programming model for bringing accelerators in, and then MPI to coordinate between these shared memory/accelerator enabled hosts.

CaliforniaKarl 2y ago

Supercomputers, yes, but also genomics workloads. The vast majority of those workloads are effectively tied to one machine, since they don’t support cross-machine scaling, nor things like MPI.

Jtsummers 2y ago
Do they not support MPI and scaling across machines because of the features of the workloads or because of the features of the systems performing the work? If the latter, then maybe they can use multiple cores using things like OpenMP and the like to get some "free" scaling, but they could be made to work with MPI or across machines. However, if it's the former, more cores won't help them.

NGRhodes 2y ago

As a fresh example, we (a University) have just this month had delivered about 9000 cores (and about 80 GPUs) of machines, these are being added to our existing 6000 cores (approx 5 year old) machines. This is a modest HPC system.