Re: [PATCH 0/8] RFC: vcpu pinning at qemu start

Avi Kivity
2008-03-05T05:28:09Z

Glauber Costa wrote:
> Hi guys,
>
> Here's a first series of patch aiming at vcpu pinning support in qemu.
> Ideally, as vcpu as just normal threads, the usual userspace tools can be used
> to set cpu affinities mask.
>
> However, It makes it very difficult to _start_ a vm with vcpus pinned, since
> we don't know the thread ids from qemu in advance, nor do we know when are the
> vcpus created.
>
> The patches introduce a -cpu-map option, that, if specified, starts the virtual cpus
> with the specified affinities.
>
> Comments? Welcome. Random rants? Not welcome, but... how can I stop you? So go ahead!
>
>

A monitor interface would be more useful than a command line option, as
it allows you to migrate the vcpus at runtime, and also control
hotplugged cpus. For unmanaged use, taskset is probably sufficient to
control affinity from the command line.

Normally I encourage splitting patches, but this is a bit extreme. 1
and 3 are pointless without each other, 4 and 5, 7 and 8. Hope that
doesn't interfere with any pay-per-patch contract.

--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.