From: Emmanuel Kasper Date: Tue, 14 Jun 2016 08:08:46 +0000 (+0200) Subject: Move Multiqueue and IO Threads description at bottom of each chapter X-Git-Url: https://git.proxmox.com/?p=pve-docs.git;a=commitdiff_plain;h=af9c6de1027b37608a511f313ac0bd26bf9c20e2 Move Multiqueue and IO Threads description at bottom of each chapter Also rename Multiqueues to Multiqueue, to match upstream description --- diff --git a/qm.adoc b/qm.adoc index e8dc3ba..375cc39 100644 --- a/qm.adoc +++ b/qm.adoc @@ -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, @@ -290,8 +291,24 @@ 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. +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 +_tap device_, ( a software loopback device simulating an Ethernet NIC ). This +tap device is added to a bridge, by default vmbr0 in {pve}. In this mode, VMs +have direct access to the Ethernet LAN on which the host is located. + * in the alternative *NAT mode*, each virtual NIC will only communicate with +the Qemu user networking stack, where a builting router and DHCP server can +provide network access. This built-in DHCP will serve adresses in the private +10.0.2.0/24 range. The NAT mode is much slower than the bridged mode, and +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 -*Multiqueues* option. This option allows the guest OS to process networking +*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. @@ -302,7 +319,7 @@ 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 +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: @@ -311,27 +328,12 @@ command: 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 +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. -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 -_tap device_, ( a software loopback device simulating an Ethernet NIC ). This -tap device is added to a bridge, by default vmbr0 in {pve}. In this mode, VMs -have direct access to the Ethernet LAN on which the host is located. - * in the alternative *NAT mode*, each virtual NIC will only communicate with -the Qemu user networking stack, where a builting router and DHCP server can -provide network access. This built-in DHCP will serve adresses in the private -10.0.2.0/24 range. The NAT mode is much slower than the bridged mode, and -should only be used for testing. - -You can also skip adding a network device when creating a VM by selecting *No -network device*. - USB Passthrough ~~~~~~~~~~~~~~~ There are two different types of USB passthrough devices: