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You are here: Home / NSX / Quick Tip: Reducing High CPU Utilization on NSX due to slow Entropy from AMD Zen4/5 CPUs

Quick Tip: Reducing High CPU Utilization on NSX due to slow Entropy from AMD Zen4/5 CPUs

07.31.2026 by William Lam // Leave a Comment

AMD Zen4/Zen5 processors have been known to have slower entropy generation, which can lead to higher CPU utilization for workloads that depend on random number generation. I recently learned from a colleague (Ross Wynne) about a simple optimization for NSX Manager that can significantly reduce CPU utilization when running on AMD Zen4/Zen5 processors.

Shut down your NSX Manager VM and add the following VM Advanced Setting. This allows the guest operating system to retrieve entropy directly from the ESXi host, which already includes optimizations for entropy generation on AMD Zen4 and Zen5 processors.

isolation.tools.getEntropy.disable = FALSE


Note: Ensure you have applied the recommended entropySource configuration for your physical ESX host in addition to this configuration change.

In my limited testing, I have observed the NSX Manager load average drop to less than 5, whereas it was consistently much higher before applying this optimization. I will continue to monitor my environment, but this is definitely a worthwhile optimization to add to your VCF homelab toolkit.

Categories // NSX, VMware Cloud Foundation Tags // VCF 9.0, VCF 9.1

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William is Distinguished Platform Engineering Architect in the VMware Cloud Foundation (VCF) Division at Broadcom. His primary focus is helping customers and partners build, run and operate a modern Private Cloud using the VMware Cloud Foundation (VCF) platform.

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