November 2, 2021 at 7:30 pm
Wanted to get feedback from others if there are any other changes they had to do at BIOS level while turning off hyper-threading. I am trying to reduce the number of cores assigned to the server ( in short goal is to cut down CPU, I completely understand I can tackle individual queries and so on to reduce CPU usage) purely from SQL licensing perspective. Avg CPU usage with HT ( 196 core with HT) was about 25%, after disabling HT we were frequently noticing CPU spikes with avg around 60%. All this is measured using perfmon, we also noticed our processes ran about 40% longer.
November 2, 2021 at 7:36 pm
removing HT will not reduce the licensing - the licensing is per core or vCpu if on a vm and the host not fully licensed (Entreprise + SA).
if it is a VM then just allocate less vCpus to it - if it is physical then the only way to reduce licensing is to physically remove processores/cores from the machine - disabling them on the machine but leaving them installed (if it is a multi processor machine) will not reduce the licensing.
November 2, 2021 at 7:58 pm
You can use CPU affinity to reduce the number of CPUs available to SQL Server.
196 cores? Wowza that's a *lot*. If you're only at 25% usage, you presumably would be able to cut that in half and still only have about 50% usage.
SQL DBA,SQL Server MVP(07, 08, 09) "It's a dog-eat-dog world, and I'm wearing Milk-Bone underwear." "Norm", on "Cheers". Also from "Cheers", from "Carla": "You need to know 3 things about Tortelli men: Tortelli men draw women like flies; Tortelli men treat women like flies; Tortelli men's brains are in their flies".
November 2, 2021 at 8:26 pm
As to licensing issues, talk to an expert on that. Licensing has gotten really complex, you need someone who truly studies to know all the details on that correctly.
SQL DBA,SQL Server MVP(07, 08, 09) "It's a dog-eat-dog world, and I'm wearing Milk-Bone underwear." "Norm", on "Cheers". Also from "Cheers", from "Carla": "You need to know 3 things about Tortelli men: Tortelli men draw women like flies; Tortelli men treat women like flies; Tortelli men's brains are in their flies".
November 2, 2021 at 8:52 pm
Sorry should have provided more details, we want to move to a smaller box with 96 cores on AWS , there is lot more details around that, but long story short I wanted to see if I am loosing in performance by disabling HT in my case looks like I am taking a performance hit. I will explore CPU affinity option too.
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