Re: [Qemu-devel] [RFC V2 10/10] cpus: reclaim allocated vCPU objects

[Gu Zheng <guz.fnst@cn.fujitsu.com>]

Hi Bharata,
On 12/08/2014 05:16 PM, Bharata B Rao wrote:

> On Thu, Aug 28, 2014 at 9:06 AM, Gu Zheng <guz.fnst@cn.fujitsu.com> wrote:
>> After ACPI get a signal to eject a vCPU, the vCPU must be
>> removed from CPU list，before the vCPU really removed,  then
>> release the all related vCPU objects.
>> But we do not close KVM vcpu fd, just record it into a list, in
>> order to reuse it.
> 
> Hi Gu Zheng,
> 
> So this approach of parking the vcpu fd in QEMU and reusing it next
> time during CPU hotplug will only work if all architectures supported
> by KVM driver are ok with reuse of vcpu object in the kernel. I am
> using relevant bits of this patch of yours with PowerPC architecture
> to support cpu unplug and I realize that there is at least one case
> where reuse of vcpu object in the kernel causes problems. Before I
> attempt to fix that in ppc KVM, I wanted to check if there is
> consensus on this approach (parking and reusing kvm vcpu fd) in QEMU.

Not yet, also no objection.
But it's the best way that I can find to handle the vcpu object without
touching the CPU array in kernel.

> 
> Also is there a latest version of this patchset that I can try ?

A new version is on the respinning, and will be sent out once the 2.2 released.

Thanks,
Gu

> 
> Regards,
> Bharata.
> .
>