Re: [PATCH] x86: Raise the hard VCPU count limit

[Avi Kivity <avi@redhat.com>]

On 07/09/2011 03:25 PM, Sasha Levin wrote:
> The patch raises the hard limit of VCPU count to 1024.
>
> This will allow developers to easily work on scalability
> and will allow users to test high VCPU setups easily without
> patching the kernel.
>
> To prevent possible issues with current setups, KVM_CAP_NR_VCPUS
> now returns the recommended VCPU limit (which is still 64) - this
> should be a safe value for everybody, while a new KVM_CAP_MAX_VCPUS
> returns the hard limit which is now 1024.
>

Can 1024 vcpus even work without interrupt remapping?

Looks like the patch will break coalesced mmio:

static int coalesced_mmio_in_range(struct kvm_coalesced_mmio_dev *dev,
                    gpa_t addr, int len)
{
     struct kvm_coalesced_mmio_zone *zone;
     struct kvm_coalesced_mmio_ring *ring;
     unsigned avail;
     int i;

     /* Are we able to batch it ? */

     /* last is the first free entry
      * check if we don't meet the first used entry
      * there is always one unused entry in the buffer
      */
     ring = dev->kvm->coalesced_mmio_ring;
     avail = (ring->first - ring->last - 1) % KVM_COALESCED_MMIO_MAX;
     if (avail < KVM_MAX_VCPUS) {
         /* full */
         return 0;
     }


-- 
error compiling committee.c: too many arguments to function