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Domain-0 CPU pinning - is it still a best practice?

  • To: xen-users@xxxxxxxxxxxxx
  • From: Andy Smith <andy@xxxxxxxxxxxxxx>
  • Date: Thu, 28 Jan 2021 14:46:48 +0000
  • Delivery-date: Thu, 28 Jan 2021 14:47:31 +0000
  • List-id: Xen user discussion <xen-users.lists.xenproject.org>
  • Openpgp: id=BF15490B; url=http://strugglers.net/~andy/pubkey.asc


A lot of the information on
https://wiki.xenproject.org/wiki/Xen_Project_Best_Practices is very
old now (e.g. shows xm stack or commands that are no longer valid
for xl). Are people still dedicating CPU cores to dom0 in modern
versions of Xen with credit2 scheduler?

If I put this on the hypervisor command line:

    dom0_max_vcpus=2 dom0_vcpus_pin

how do I know which PCPUs dom0 will be pinned to?

I am aware that after boot I can:

# xl vcpu-pin Domain-0 0 0 -
# xl vcpu-pin Domain-0 1 1 -

to pin Domain-0 to PCPUs 0 and 1.

And then potentially set:

cpus = "all,^0,^1"

in every guest config to tell them to use "all PCPUs except 0 or 1",
thus leaving PCPUs 0 and 1 exclusively used by Domain-0.




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