Messages in this thread | | | From | Maxim Levitsky <> | Date | Sat, 4 Nov 2017 11:55:14 +0200 | Subject | Guaranteed allocation of huge pages (1G) using movablecore=N doesn't seem to work at all |
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Hi!
My system has 64G of ram and I want to create 32 1G huge pages to use in KVM virtualization, on demand, only when VM is running.
So I booted the kernel with 'hugepagesz=1G hugepages=0 default_hugepagesz=1G movablecore=40G'
However I still can't allocate the pages reliably. For instance this simple script is enough to make it not possible to even allocate one 1G huge page after few dozens of iterations:
while true ; do sudo hugeadm --enable-zone-movable --pool-pages-min 1G:0G sudo hugeadm --enable-zone-movable --pool-pages-min 1G:60G done
I disabled mlock systemwide (now ulimit -l shows 0), I still see 8 pages mlocked in zone 'Movable' but this is not enough to explain this nr_mlock 8
I do have around 64GB of swap too, but I see no even an attempt to use it.
# free total used free shared buff/cache available Mem: 65887928 1748344 62640276 61688 1499308 62053832 Swap: 67108860 0 67108860
Any idea about what is going on?
This was tested on 4.14.0-rc5 (my custom compiled) and on several older kernels (4.10,4.12,4.13) from ubuntu repositories.
Disabling/enabling transparent huge pages in the kernel config didn't make a difference.
VT-d was enabled during the tests (intel_iommu=on,igfx_off) if that would make any difference, but no VM was started when I run the above script, in fact I run it just after the system booted.
Best regards, Maxim Levitsky
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