docs: Document limitation of maximum vcpu count used with <topology>

qemu requires that the topology equals to the maximum vcpu count.
Document this along with the API to set maximum vcpu count and the XML
element.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1426220
This commit is contained in:
Peter Krempa 2017-04-04 16:02:21 +02:00
parent 2e8c60958a
commit 4661a1868b
3 changed files with 8 additions and 3 deletions

View File

@ -1401,7 +1401,10 @@
virtual CPU provided to the guest. Three non-zero values have to be virtual CPU provided to the guest. Three non-zero values have to be
given for <code>sockets</code>, <code>cores</code>, and given for <code>sockets</code>, <code>cores</code>, and
<code>threads</code>: total number of CPU sockets, number of cores per <code>threads</code>: total number of CPU sockets, number of cores per
socket, and number of threads per core, respectively.</dd> socket, and number of threads per core, respectively. Hypervisors may
require that the maximum number of vCPUs specified by the
<code>cpus</code> element equals to the number of vcpus resulting
from the topology.</dd>
<dt><code>feature</code></dt> <dt><code>feature</code></dt>
<dd>The <code>cpu</code> element can contain zero or more <dd>The <code>cpu</code> element can contain zero or more

View File

@ -7010,7 +7010,8 @@ virDomainSetVcpus(virDomainPtr domain, unsigned int nvcpus)
* CPU limit is altered; generally, this value must be less than or * CPU limit is altered; generally, this value must be less than or
* equal to virConnectGetMaxVcpus(). Otherwise, this call affects the * equal to virConnectGetMaxVcpus(). Otherwise, this call affects the
* current virtual CPU limit, which must be less than or equal to the * current virtual CPU limit, which must be less than or equal to the
* maximum limit. * maximum limit. Note that hypervisors may not allow changing the maximum
* vcpu count if processor topology is specified.
* *
* If @flags includes VIR_DOMAIN_VCPU_GUEST, then the state of processors is * If @flags includes VIR_DOMAIN_VCPU_GUEST, then the state of processors is
* modified inside the guest instead of the hypervisor. This flag can only * modified inside the guest instead of the hypervisor. This flag can only

View File

@ -2477,7 +2477,8 @@ marked as hotpluggable.
The I<--maximum> flag controls the maximum number of virtual cpus that can The I<--maximum> flag controls the maximum number of virtual cpus that can
be hot-plugged the next time the domain is booted. As such, it must only be be hot-plugged the next time the domain is booted. As such, it must only be
used with the I<--config> flag, and not with the I<--live> or the I<--current> used with the I<--config> flag, and not with the I<--live> or the I<--current>
flag. flag. Note that it may not be possible to change the maximum vcpu count if
the processor topology is specified for the guest.
=item B<setvcpu> I<domain> I<vcpulist> [I<--enable>] | [I<--disable>] =item B<setvcpu> I<domain> I<vcpulist> [I<--enable>] | [I<--disable>]
[[I<--live>] [I<--config>] | [I<--current>]] [[I<--live>] [I<--config>] | [I<--current>]]