Re: Windows DomU: Network Issues

[James Dingwall <james-xen@xxxxxxxxxxxxxx>]

On Thu, May 06, 2021 at 07:47:29PM +0000, Paul Leiber wrote:
> Hi everybody,
> 
> I am a novice Xen user. I recently started to set up my home server (file 
> server, print server, media server, TV backend etc.) using Xen based VMs 
> installed on a Debian 10 dom0. I mostly followed the steps laid out in 
> https://wiki.xenproject.org/wiki/Xen_Project_Beginners_Guide. The linux domUs 
> worked like a charm right from the beginning.
> 
> I then wanted to install Windows Server 2012 on a domU for the TV backend 
> (MediaPortal). Following the steps in the above mentioned guide, I could 
> install the Windows system alright. I could solve most of the obvious issues 
> (like mouse pointer off, keyboard layout not correct etc.). However, I 
> utterly failed to get a decent network connection. Transfer speed while 
> copying a large file from a Samba file server on one of the Debian domUs to 
> the Windows Server 2012 domU remained around 1-3 Mbit/s. I of course 
> installed the Windows PV drivers from 
> https://xenproject.org/windows-pv-drivers/, tried different options in the 
> config file, added the GplPv option to the boot options (as described in 
> https://wiki.xenproject.org/wiki/Xen_Windows_GplPv/Installing), but nothing 
> helped. The slow connection made it pointless to use the Windows Server DomU 
> as a media/TV server. Also, there was a persistent error on Windows Update so 
> I couldn't install any updates. I tried a fresh install, but with the same 
> result. I gave up and installed VDR on another Debian DomU which works o.k.

It is a while since I spun up a Windows VM but I vaguely remember having to 
disable checksum offloading in the guest to solve some performance issues... 
From what I can find "IPv4 Checksum Offload", "UDP Checksum Offload (IPv4)" and 
"TCP Checksum Offload (IPv4)" specifically.  There are similar IPv6 settings if 
you have that enabled.

James

> 
> But now it turns out my wife is not happy with the Kodi frontend, so I am 
> forced to give Windows another try. This time, I installed Windows 10, but 
> the results are the same (except for the Windows Update, which now works). 
> Now I am lost. Any help for pinpointing the error and/or finding a solution 
> (besides the obvious one, to replace my wife ;-) would be very much 
> appreciated. Or is this in the end the maximum network speed to be expected 
> on a HVM domU like Windows?
> 
> Further observations from Windows 10 device manager on the domU:
> - There is one device without a driver (yellow triangle), the device is 
> called XSC000 XENVIF 0
> - The system devices XenServer PV Interface, XenServer PV Bus (twice), and 
> XenServer PV Network Class seem to be installed correctly
> - The NIC installed is shown as Realtek RTL8139C+ Fast Ethernet NIC
> 
> Xen config file for the Windows domU:
> 
> kernel = "/usr/lib/xen-4.0/boot/hvmloader"
> type='hvm'
> memory = 4096
> vcpus=4
> name = "windows"
> vif = ['bridge=xenbr0']
> disk = ['phy:/dev/vg0/windows,hda,w']
> device_model_version = 'qemu-xen'
> boot="c"
> hdtype = 'ahci'
> acpi = 1
> apic = 1
> xen_platform_pci = 1
> vendor_device = 'xenserver'
> stdvga = 1
> device_model_version = 'qemu-xen'
> boot = "d"
> sdl = 0
> pae = 1
> serial = 'pty'
> usb = 1
> usbdevice = 'tablet'
> keymap = 'de'
> vnc = 1
> vnclisten = "0.0.0.0"
> vncpasswd = ""
> 
> xl info:
> 
> host                   : xxx
> release                : 4.19.0-14-amd64
> version                : #1 SMP Debian 4.19.171-2 (2021-01-30)
> machine                : x86_64
> nr_cpus                : 4
> max_cpu_id             : 3
> nr_nodes               : 1
> cores_per_socket       : 4
> threads_per_core       : 1
> cpu_mhz                : 1992.095
> hw_caps                : 
> bfebfbff:77faf3ff:2c100800:00000121:0000000f:009c6fbf:00000000:00000100
> virt_caps              : hvm hvm_directio
> total_memory           : 32542
> free_memory            : 18773
> sharing_freed_memory   : 0
> sharing_used_memory    : 0
> outstanding_claims     : 0
> free_cpus              : 0
> xen_major              : 4
> xen_minor              : 11
> xen_extra              : .4
> xen_version            : 4.11.4
> xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 
> hvm-3.0-x86_32p hvm-3.0-x86_64
> xen_scheduler          : credit
> xen_pagesize           : 4096
> platform_params        : virt_start=0xffff800000000000
> xen_changeset          :
> xen_commandline        : placeholder dom0_mem=1024M,max:1024M 
> xen-pciback.hide=(01:00.0)
> cc_compiler            : gcc (Debian 8.3.0-6) 8.3.0
> cc_compile_by          : pkg-xen-devel
> cc_compile_domain      : lists.alioth.debian.org
> cc_compile_date        : Fri Dec 11 21:33:51 UTC 2020
> build_id               : 6d8e0fa3ddb825695eb6c6832631b4fa2331fe41
> xend_config_format     : 4
> 
> Logs from /var/log/xen didn't show errors, but can of course be provided if 
> needed.
> 
> Best regards,
> 
> Paul
>