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SQL Server CPU usage available in sys.dm_os_ring_buffers DMV starting SQL Server 2019 RC on Linux

Tejas Shah's avatar
Tejas Shah
Icon for Microsoft rankMicrosoft
Aug 27, 2019
Sys.dm_os_ring_buffers DMV has been a key DMV used for monitoring SQL Server by built-in tools as well as third party monitoring utilities. When SQL Server 2017 was released on Linux, unfortunately t...
Updated Sep 04, 2019
Version 2.0
SQLServerTiger
chadbaldwin's avatar
chadbaldwin
Copper Contributor
Aug 22, 2024

So I'm just here to +1 the other comment. This view does not seem to report accurate CPU usage. I realize it is some sort of aggregate/average over the course of a minute...but it still does not report accurate values.

For non-hypervisor instances, it seems to report ProcessUtilization values WELL above their actual CPU % when viewing it directly in Task Manager (or similar). For example, we have one instance that will show ProcessUtilization values as high as 300+.

I've spent hours trying to figure out if maybe for non-hypervisors this value is multiplied by the number of NUMA nodes, memory nodes, sockets, etc....but nothing has proven to be accurate.

On top of that, the SystemIdle value does not appear to be accurate either. For example, I ran a query which steadily held the instance CPU at 45% and System Idle at 55% (when viewing Task Manager). It held this reading for 5+ minutes without deviating. Which means the averages should also be 45/55.

However, sys.dm_os_ring_buffers reported a ProcessUtilization value of 180 and a SystemIdle of 50.

And yes...this is still true even for SQL Server 2022 (running on Windows Server, not Linux). Could someone please look into this? I'm not necessarily asking for it to be "fixed" , but maybe at the very least, provide a formula/method for normalizing that value back to being 100 based.

This is obviously an ongoing issue based on the number of feature suggestions that have been submitted specifically mentioning this issue...

https://feedback.azure.com/d365community/idea/5e7f7457-8125-ec11-b6e6-000d3a4f0da0
https://feedback.azure.com/d365community/idea/6b113656-5d25-ec11-b6e6-000d3a4f0da0
https://feedback.azure.com/d365community/idea/8d09dfb3-4a25-ec11-b6e6-000d3a4f0da0
https://feedback.azure.com/d365community/idea/8e09dfb3-4a25-ec11-b6e6-000d3a4f0da0
https://feedback.azure.com/d365community/idea/9320f59a-4a25-ec11-b6e6-000d3a4f0da0
https://feedback.azure.com/d365community/idea/cefc64f0-8125-ec11-b6e6-000d3a4f0da0
https://feedback.azure.com/d365community/idea/f7db3568-6f25-ec11-b6e6-000d3a4f0da0
https://feedback.azure.com/d365community/idea/fe0aaeb8-5025-ec11-b6e6-000d3a4f0da0