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Cycles not using both NUMA Nodes on Dual Xeon Setup
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System Information
Operating system: Windows 7 pro 64bit
CPU: 2*Intel Xeon e5-2696v3

Blender Version
Broken: 2.80.xx
Worked: 2.79

Short description of error
When i render, Cycles wont use both NUMA Nodes (or CPU Groups) but only one. Even if i change from "Auto detect" to "Fixed" and fill in "72" inside the Performance-Tab, it spawns 72 Buckets but will actually use only 36 CPU Threads. While the auto detect option also didnt work in 2.79, the "fixed" parameter worked and used all 72 Threads for rendering.

Since this occurs only on this machine and not my second one (only 48 threads), my guess is that this is an issue with Windows CPU Grouping that will split everything that exceeds 64 Threads into Groups. If a software is not aware of this, they can only use one NUMA Node (or cpu Group). In my case that would be exactly 36 Threads.



Event Timeline

Brecht Van Lommel (brecht) lowered the priority of this task from Needs Triage by Developer to Needs Information from User.EditedFeb 14 2019, 1:48 PM

Which exact 2.79 and 2.80 version are you testing (date from the splash screen)?

Dosent work with: 2.80.44 (2019-02-07)

Works with : 2.79.6 (2018-11-09)

Brecht Van Lommel (brecht) raised the priority of this task from Needs Information from User to Normal.Feb 14 2019, 4:47 PM

Can confirm that it is working again on my dual e5-2696v3 machine. Autodetect will (as before) only show one node (36 threads in my case) but if i put in 72 manually, it uses all cores/threads. Thanks for fixing!