Does UnRAID Have Hugepages Support, IOMMU super pages?


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A little new to this topic, but basically from what I've read if the processor supports it, it is a good idea to enable it.

From what I can tell this needs to be added to the XML in the

<memoryBacking> as such

<memoryBacking>
<hugepages/>
</memoryBacking>

 

I looked at my XML created by the VM manager and it is not there by default (nor selectable at VM creation).

I understand I can add it manually and test, etc... however there seems to (possibly) be more to it.

 

The support for this also looks to be needed in other files such as /etc/sysctl.conf (not sure if this is the same in UnRAID implementation).

 

I know my processor supports it, so I'd like to enable it. I started reading about it at the bottom here http://vfio.blogspot.com/2015_10_01_archive.html

"A more subtle feature also found in these E series processors is support for IOMMU super pages.  The datasheets for the E5 Xeons and these High End Desktop Processors indicate support for 2MB and 1GB IOMMU pages while the standard Core i5 and i7 only support 4KB pages"

 

And found some instructions for KVM here https://help.ubuntu.com/community/KVM%20-%20Using%20Hugepages

 

 

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  • 3 years later...

Hi M0ngr31,

 

I think I may have stumbled upon the root cause, after watching an episode of linus' tech tips. He had some problems with his VM and it turned out to cause by a great amount of RAM. I have 384GB (funny enough the same amount Linus had in his machine) How much do you have in yours?

I have made a thread which describing my scenario, maybe you can confirm?

https://forums.unraid.net/topic/82427-spontaneous-reboots/?tab=comments#comment-764418

 

/Alphahelix

Edited by Alphahelix
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  • 1 month later...

I second this, I have a dell t620 with 128G of RAM and I a guest that is pinned to the second CPU. I want all of that guests 64G RAM to come from the second numa node and all my other vms can just use THP and be on the first core with unraid. THP is quite cpu intensive.
Would something like this work. https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/performance_tuning_guide/sect-red_hat_enterprise_linux-performance_tuning_guide-memory-configuring-huge-pages

Thanks in advance, only been here a couple of days.

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