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Move Multiqueue and IO Threads description at bottom of each chapter

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Also rename Multiqueues to Multiqueue, to match upstream description
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Emmanuel Kasper 2016-06-14 10:08:46 +02:00 committed by Dietmar Maurer
parent 1ff7835b6b
commit af9c6de102
1 changed files with 29 additions and 27 deletions
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@ -169,6 +169,7 @@ when the filesystem of a VM marks blocks as unused after removing files, the
emulated SCSI controller will relay this information to the storage, which will
then shrink the disk image accordingly.
.IO Thread
The option *IO Thread* can only be enabled when using a disk with the *VirtIO* controller,
or with the *SCSI* controller, when the emulated controller type is *VirtIO SCSI*.
With this enabled, Qemu uses one thread per disk, instead of one thread for all,
@ -290,33 +291,6 @@ when importing a VM from another hypervisor.
{pve} will generate for each NIC a random *MAC address*, so that your VM is
addressable on Ethernet networks.
If you are using the VirtIO driver, you can optionally activate the
*Multiqueues* option. This option allows the guest OS to process networking
packets using multiple virtual CPUs, providing an increase in the total number
of packets transfered.
//http://blog.vmsplice.net/2011/09/qemu-internals-vhost-architecture.html
When using the VirtIO driver with {pve}, each NIC network queue is passed to the
host kernel, where the queue will be processed by a kernel thread spawn by the
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 Multiqueues, 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:
`ethtool -L eth0 combined X`
where X is the number of the number of vcpus of the VM.
You should note that setting the Multiqueues parameter to a value greater
than one will increase the CPU load on the host and guest systems as the
traffic increases. We recommend to set this option only when the VM has to
process a great number of incoming connections, such as when the VM is running
as a router, reverse proxy or a busy HTTP server doing long polling.
The NIC you added to the VM can follow one of two differents models:
* in the default *Bridged mode* each virtual NIC is backed on the host by a
@ -332,6 +306,34 @@ should only be used for testing.
You can also skip adding a network device when creating a VM by selecting *No
network device*.
.Multiqueue
If you are using the VirtIO driver, you can optionally activate the
*Multiqueue* option. This option allows the guest OS to process networking
packets using multiple virtual CPUs, providing an increase in the total number
of packets transfered.
//http://blog.vmsplice.net/2011/09/qemu-internals-vhost-architecture.html
When using the VirtIO driver with {pve}, each NIC network queue is passed to the
host kernel, where the queue will be processed by a kernel thread spawn by the
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:
`ethtool -L eth0 combined X`
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
traffic increases. We recommend to set this option only when the VM has to
process a great number of incoming connections, such as when the VM is running
as a router, reverse proxy or a busy HTTP server doing long polling.
USB Passthrough
~~~~~~~~~~~~~~~
There are two different types of USB passthrough devices: