Category: CPU

NUMA Deep Dive Part 1: From UMA to NUMA

Non-uniform memory access (NUMA) is a shared memory architecture used in today's multiprocessing systems. Each CPU is assigned its own local memory and can access memory from other CPUs in the system. Local memory access provides a low latency - high bandwidth performance. While accessing memory owned by the other CPU...

Introduction 2016 NUMA Deep Dive Series

Recently I've been analyzing traffic to my site and it appears that a lot CPU and memory articles are still very popular. Even my first article about NUMA published in february 2010 is still in high demand. And although you see a lot of talk about the upper levels and...

Contention on lightly utilized hosts

Often I receive the question why a virtual machine is not receiving resources while the ESXi host is lightly utilized and is accumulating idle time. This behavior is observed while reviewing the DRS distribution chart or the Host summary tab in the vSphere Client. A common misconception is that low...

Beating a dead horse - using CPU affinity

Lately the question about setting CPU affinity is rearing its ugly head again. Will it offer performance advantages for the virtual machine? Yes it can, but only in very specific cases. Additional settings and changes to the virtual infrastructure are required to obtain a performance increase over the default scheduling...