Hyperthreading in Greenplum hosts

Products

• VMware Tanzu Greenplum
• VMware Tanzu Greenplum / Gemfire

Issue/Introduction

This article provides information about hyperthreading setting on Greenplum Database (GPDB) hosts.

Resolution

Review the Hyperthreading note in Hardware and Network.

Resource Groups - one of the key Greenplum Database features - can control transaction concurrency, CPU and memory resources, workload isolation, and dynamic bursting.

When using resource groups to control resource allocation on Intel based systems, consider switching off Hyper-Threading (HT) in the server BIOS (for Intel cores the default is ON). Switching off HT might cause a small throughput reduction (less than 15%), but can achieve greater isolation between resource groups, and higher query performance with lower concurrency workloads.

Also see the "Example Segment Host Hardware Stack" in the "About the Greenplum Architecture" documentation:

The number of segment instances per segment host is determined by the number of effective CPUs or CPU core. For example, if your segment hosts have two dual-core processors, you may have two or four primary segments per host. If your segment hosts have three quad-core processors, you may have three, six or twelve segments per host. Performance testing will help decide the best number of segments for a chosen hardware platform.