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Feature: hpc8a instances CPU count customization #7422
Description
Hpc8a instances are available in a single 96xlarge size with a 1:4 core-to-memory ratio, enabling customers to right-size compute capacity by customizing the number of cores at instance launch.
It appears the hpc8a instances allow you to specify the amount of CPUs to launch with.
Looking at https://docs.aws.amazon.com/parallelcluster/latest/ug/Scheduling-v3.html it appears that there is no option tp specify this at the time.
A workaround could be defining the custom amount of CPUs in a launch template and then reference that launch template. But I have yet to test this.
Activity
hanwen-cluster commentedon Jun 4, 2026
Hi Ezri!
ParallelCluster launches instances with all vCPU active.
You are right that you can customize the launch using LaunchTemplateOverrides.
Can you provide your usecase of only making a subset of vCPU active?
Thank you,
Hanwen
ezrizhu commentedon Jun 4, 2026
Disabling a subset of vCPUs allows more L3 cache and memory bandwidth per undisabled cores.
So for jobs that faces diminishing returns after a certain amount of core counts, disabling cores should allow for some job performance improvements.