[pve-devel] [PATCH docs 1/2] qm: multiqueue specify that it needs to be vCPUs not cores

[Stefan Sterz]

total number of cores != vCPUs if there is more than one socket
configured. according to the redhat docs it should be vCPUs not cores:

> Multi-queue virtio-net provides the greatest performance benefit when:
> [..]
> - The number of queues is equal to the number of vCPUs.

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/virtualization_tuning_and_optimization_guide/sect-virtualization_tuning_optimization_guide-networking-techniques#sect-Virtualization_Tuning_Optimization_Guide-Networking-Multi-queue_virtio-net
Signed-off-by: Stefan Sterz <s.sterz at proxmox.com>
---
 qm.adoc | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/qm.adoc b/qm.adoc
index 1170dd1..8630419 100644
--- a/qm.adoc
+++ b/qm.adoc
@@ -770,14 +770,15 @@ vhost driver. With this option activated, it is possible to pass _multiple_
 network queues to the host kernel for each NIC.
 
 //https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Virtualization_Tuning_and_Optimization_Guide/sect-Virtualization_Tuning_Optimization_Guide-Networking-Techniques.html#sect-Virtualization_Tuning_Optimization_Guide-Networking-Multi-queue_virtio-net
-When using Multiqueue, it is recommended to set it to a value equal
-to the number of Total Cores of your guest. You also need to set in
-the VM the number of multi-purpose channels on each VirtIO NIC with the ethtool
-command:
+When using Multiqueue, it is recommended to set it to a value equal to the
+number of vCPUs of your guest. Remember that the number of vCPUs is the number
+of sockets times the number of cores configured for the VM. You also need to set
+the number of multi-purpose channels on each VirtIO NIC in the VM with this
+ethtool command:
 
 `ethtool -L ens1 combined X`
 
-where X is the number of the number of vcpus of the VM.
+where X is the number of the number of vCPUs of the VM.
 
 You should note that setting the Multiqueue parameter to a value greater
 than one will increase the CPU load on the host and guest systems as the
-- 
2.39.2