[pve-devel] win8r2 virtio net problems

[Alexandre DERUMIER]

Good news,

on win2012, I have enable  "offload Tx LSO option" in virtio net driver

now, vm->host, jump from 500mbits to 1,5gbits !   (always cpu limited)

now sure that lso is supported by all windows versions, I need to check that.
(and stability too)



(tests are done with iperf, default 64k windows size)


----- Mail original ----- 

De: "Daniel Hunsaker" <danhunsaker at gmail.com> 
À: "Alexandre DERUMIER" <aderumier at odiso.com> 
Cc: pve-devel at pve.proxmox.com, "Dietmar Maurer" <dietmar at proxmox.com> 
Envoyé: Dimanche 30 Mars 2014 05:50:18 
Objet: Re: [pve-devel] win8r2 virtio net problems 


Ultimately, the Windows network stack is pretty terrible. You'll get some improvements from tweaking things (and it would be nice to have those tweaks applied automatically wherever possible), but it'll never be near as efficient as a Linux or BSD guest. Microsoft hasn't done much with it since they adapted it (poorly) from BSD's back around the time of NT4 (or earlier), aside from fixing a few of the more major bugs. Personally, I'd avoid using Windows servers for anything network-heavy, whenever possible. 
On Mar 29, 2014 9:36 PM, "Alexandre DERUMIER" < aderumier at odiso.com > wrote: 


I have done test with win2012 + virtio-net, no tuning, last virtio driver. 

on a small 2core 5110 @ 1.60GHz, I can achieve around 500mbit/s 

But the cpu is limiting the speed. (so 500mbits vm<->host, or 250mbits vm<->vm) 

(seem that virtio-net windows use a lot more cpu than linux) 

I try to play with offloading to see if I can improve performance. 


----- Mail original ----- 

De: "Alexandre DERUMIER" < aderumier at odiso.com > 
À: "Dietmar Maurer" < dietmar at proxmox.com > 
Cc: pve-devel at pve.proxmox.com 
Envoyé: Samedi 29 Mars 2014 13:22:21 
Objet: Re: [pve-devel] win8r2 virtio net problems 

Hi, I never reach myself more than 900Mbits with windows guest. (2003 > 2012, any virito driver 

But 30mbit/s seem very slow. 

Maybe trying to play with disabling offloading options (in windows guest driver options) ? gro,gso,... 


----- Mail original ----- 

De: "Dietmar Maurer" < dietmar at proxmox.com > 
À: pve-devel at pve.proxmox.com 
Envoyé: Vendredi 28 Mars 2014 15:07:23 
Objet: [pve-devel] win8r2 virtio net problems 



Hi all, 

we just observed bad performance values with virtio network on win8r2 guests. 

A simple iperf from a VM to the host shown about 700Mbit/s. 

Even worse, iperf between 2 win8r2 guests on the same bridge shown below 30Mbit/s. 

Using linux VMs, I am able to get > 9Gbit/s. 

I already made all optimizations suggested at: 

http://pve.proxmox.com/wiki/Paravirtualized_Network_Drivers_for_Windows 

Any ideas? 

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