[Libvirt-cim] [PATCH] Add dynamic VCPU adjustments

[Heidi Eckhart]

Dan Smith wrote:
> # HG changeset patch
> # User Dan Smith <danms at us.ibm.com>
> # Date 1201029734 28800
> # Node ID 84f80a8040eb29109d0fce50b582582527c2e50e
> # Parent  47438edf32be70e65bdb814ab609a70304fad2f4
> Add dynamic VCPU adjustments
>
> Signed-off-by: Dan Smith <danms at us.ibm.com>
>
> diff -r 47438edf32be -r 84f80a8040eb libxkutil/device_parsing.c
> --- a/libxkutil/device_parsing.c	Tue Jan 22 10:55:59 2008 -0800
> +++ b/libxkutil/device_parsing.c	Tue Jan 22 11:22:14 2008 -0800
> @@ -897,11 +897,38 @@ static int change_memory(virDomainPtr do
>          return 1;
>  }
>
> +static int change_vcpus(virDomainPtr dom, int delta)
> +{
> +        int count = 32;
> +        int max;
> +        virVcpuInfoPtr foo;
> +
> +        /* This is retarded, but I don't think there's an API to
> +         *   expose the total VCPU number otherwise
> +         */
>   
I saw that virDomainInfo contains a field nrVirtCpu. Maybe this is an 
alternative.
> +        for (max = count; max == count; max += 32) {
> +                foo = calloc(max, sizeof(*foo));
> +                count = virDomainGetVcpus(dom, foo, max, NULL, 0);
>   
Wouldn't the case "virDomainGetVcpus = 32" cause an endless loop ? On 
the other hand ... I can not quite follow the reason of this for loop, 
which exits right after the first run in case of "count < 32" ?
> +                free(foo);
> +        }
> +
> +        CU_DEBUG("Changing VCPUs of %s from %i to %i",
> +                 virDomainGetName(dom),
> +                 count,
> +                 count + delta);
> +
> +        virDomainSetVcpus(dom, count + delta);
>   
This function returns -1 in case of failure. Shouldn't this error case 
be reported to the caller ? With the current setup the caller expects 
that everything worked.
> +
> +        return 1;
> +}
> +
>  int attach_device(virDomainPtr dom, struct virt_device *dev)
>  {
>          if ((dev->type == VIRT_DEV_NET) ||
>              (dev->type == VIRT_DEV_DISK))
>                  return _change_device(dom, dev, true);
> +        else if (dev->type == VIRT_DEV_VCPU)
> +                return change_vcpus(dom, 1);
>
>          CU_DEBUG("Unhandled device type %i", dev->type);
>
> @@ -913,6 +940,8 @@ int detach_device(virDomainPtr dom, stru
>          if ((dev->type == VIRT_DEV_NET) ||
>              (dev->type == VIRT_DEV_DISK))
>                  return _change_device(dom, dev, false);
> +        else if (dev->type == VIRT_DEV_VCPU)
> +                return change_vcpus(dom, -1);
>
>          CU_DEBUG("Unhandled device type %i", dev->type);
>
>
>   


-- 
Regards

Heidi Eckhart
Software Engineer
IBM Linux Technology Center - Open Hypervisor