KVM - User contributions [en]

KVM Forum 2017 BOF

2017-07-18T14:07:22Z

Yanv:

= Introduction =

We will reserve some time for people to get together and discuss
strategic decisions as well as other topics that are best solved within
smaller groups. This time can also be used for hands-on hacking
sessions.

If you are interested in organizing such a group time event, please add
it to the list '''before''' KVM Forum, so people have time to organize which
one they will attend.

Adding links to this wiki is restricted. If you have problems adding your
BoF, please send it to the program committee at
[mailto:kvm-forum-2017-pc@redhat.com kvm-forum-2017-pc@redhat.com].

= BoF Ideas =

=== Windows guests on KVM/QEMU ===

'''Anything and everything related to running Windows on KVM/QEMU'''

What's new, what's broken, what's coming in the future. Topics may include (feel free to add your own):

* Windows guest performance tuning
* VMbus on KVM
* Hyper-V nested on KVM
* Windows drivers for new virtio devices (virtio-gpu, virtio-vsock, virtio-9p, ...)
* Hyper-V enlightenments exposed by KVM
* Debugging, host-side MEMORY.DMP generation

'''Links:'''
* [https://github.com/virtio-win/kvm-guest-drivers-windows virtio-win GitHub page]

'''People:'''
* Ladi Prosek <lprosek@redhat.com> (organizer)
* Denis Lunev <den@openvz.org>
* Roman Kagan <rkagan@virtuozzo.com>
* Yan Vugenfirer <yan@daynix.com>
* Dmitry Fleytman <dmitry@daynix.com>
* Sameeh Jubran <sameeh@daynix.com>

== BoF idea template ==

<pre>
=== TITLE ===

'''Summary:''' Short description of the idea

Detailed description of the idea.

'''Links:'''
* Wiki links to relevant material
* External links to mailing lists or web sites

'''People:'''
* Your Name (organizer)
* People that want to attend this session
</pre>

WindowsGuestDrivers/kvmnet/registry

2011-01-15T18:48:40Z

Yanv:

This page describes best practice for configuring Windows TCP\IP related parameters to archive the best performance with Windows guests.
Those parameters are unrelated to kvm\VirtIO drivers , rather general Windows settings.
After changing those setting reboot is required for the changes to effect the system.

= Windows XP and 2003 registry settings =

== Registry settings ==

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\AFD\Parameters]

"DefaultSendWindow"=dword:00100000

"DefaultReceiveWindow"=dword:00100000

"FastSendDatagramThreshold"=dword:00004000

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters]

"Tcp1323Opts"=dword:00000001

"TcpWindowSize"=dword:00100000

* Tcp1323Opts - allows the scaling of the TCP window above 16k. For more info read [http://technet.microsoft.com/en-us/library/cc938205.aspx Tcp1323Opts]
* "DefaultSendWindow", "DefaultReceiveWindow" and "TcpWindowSize" control TCP window size
* "FastSendDatagramThreshold" - controls fast UDP transmit.

== Additional links ==
* [http://technet.microsoft.com/en-us/library/cc781532(WS.10).aspx Windows Sockets and DNS Registry Parameters]
* [http://support.microsoft.com/kb/235257 Server Does Not Use All Bandwidth Available When Streaming Files with Bit Rates over 100 Kbps]

= Starting from Vista =
Starting from Windows Vista the mentioned above setting are not effecting Windows networking stack.

netsh configuration tool should be used to configure the networking settings.

== Disable Windows Scaling heuristics ==
Starting from Windows Windows Vista, Windows can disregard user TCP Windows setings. This behavior could be desabled:

netsh int tcp set heuristics disabled
possible settings are: disabled,enabled,defaul

The corresponding Registry value (not necessary to edit if setting via netsh) is located in:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\Tcpip\Parameters
EnableWsd=0
(default: 1, recommended: 0)

== TCP Auto-Tuning ==
To turn off the default receive window auto tuning behavior:

netsh int tcp set global autotuninglevel=disabled

The default auto-tuning level is "normal", possible settings are:

disabled: uses a fixed value for the tcp receive window. Limits it to 64KB.
highlyrestricted: allows the receive window to grow beyond its default value, very conservatively.
restricted: somewhat restricted growth of the tcp receive window beyond its default value.
normal: default value, allows the receive window to grow to accommodate most conditions.
experimental: allows the receive window to grow to accommodate extreme scenarios (It enables RWIN values of over 16 MB).

== Compound TCP ==
To increase the TCP Windows with the faster rate Compound TCP should be enabled.
On Vista and Windows 7, CTCP is off by default. On Windows 2008 it is on.

To enable CTCP:
netsh int tcp set global congestionprovider=ctcp

To disable CTCP:
netsh int tcp set global congestionprovider=none

WindowsGuestDrivers/kvmnet/registry

2011-01-15T18:24:50Z

Yanv:

WindowsGuestDrivers/kvmnet/registry

2011-01-15T17:56:42Z

Yanv: