Re: Number of threads for virtual machine process

Paolo Bonzini
2015-02-17T06:52:01Z

On 17/02/2015 05:44, mad Engineer wrote:
> Thanks for the response.
> Can a vm process create any number of extra threads based
> on i/o requirement ,or is there any relation between number of VCPU
> allowed and these extra threads.

No, there is not relation. The I/O threads are created by QEMU, which
is a userspace program that uses KVM. Different implementations could
do I/O in a different way. Alternatively, QEMU itself can use the Linux
AIO API. In that case it still creates threads to do fdatasync, but not
to do read/write.

> I hope these threads are for disk i/o and for network it uses
> vhost-'pid' process.

For network it can use vhost or do everything into the main thread of QEMU.

Paolo