https://bugzilla.redhat.com/show_bug.cgi?id=1135491
$ virsh iothread --help
NAME
iothreadpin - control domain IOThread affinity
SYNOPSIS
iothreadpin <domain> <iothread> <cpulist> [--config] [--live] [--current]
DESCRIPTION
Pin domain IOThreads to host physical CPUs.
OPTIONS
[--domain] <string> domain name, id or uuid
[--iothread] <number> IOThread ID number
[--cpulist] <string> host cpu number(s) to set
--config affect next boot
--live affect running domain
--current affect current domain
Using the output from iothreadsinfo, allow changing the pinned CPUs for
a single IOThread.
$ virsh iothreadsinfo $dom
IOThread ID CPU Affinity
---------------------------------------------------
1 2
2 3
3 0-1
$ virsh iothreadpin $dom 3 0-2
Then view the change
$ virsh iothreadsinfo $dom
IOThread ID CPU Affinity
---------------------------------------------------
1 2
2 3
3 0-2
If an invalid value is supplied or require option missing,
then an error will be displayed:
$ virsh iothreadpin $dom 4 3
error: invalid argument: iothread value out of range 4 > 3
$ virsh iothreadpin $dom 3
error: command 'iothreadpin' requires <cpulist> option
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