Re: Network traffic performance drops when two domUs share the pipe.

["Mathew, Cherry G." <c%bow.st@localhost>]

On May 22, 2023 1:26:38 PM UTC, Manuel Bouyer <bouyer%antioche.eu.org@localhost> wrote:
>On Mon, May 22, 2023 at 04:25:54AM +0000, Mathew, Cherry G.* wrote:
>> Hi There,
>> 
>> I have an outbound pipe that can hit about 1MBps downstream on dom0 or a
>> single pv domU.
>> 
>> When I run a hvm domU as well, the total bandwidth performance of both
>> domUs combined drops to about 20-30% (I don't have exact numbers as I
>> haven't figured out a way to measure this), and sometimes, I notice that
>> the connections from one or the other domU gets dropped.
>> 
>> This is on NetBSD 10.0_BETA dom0 with a NetBSD 9.3 pv domU and a FreeBSD
>> 13.1-RELEASE hvm domU.
>> 
>> I'm wondering if anyone else is seeing this behaviour.
>
>1MBps doesn't look that big. I have several Xen servers with gigabit
>connectivity, and multiple domUs and didn't notice such issues.
>

Perhaps the slower speed makes it noticeable. In my case , traffic on one domU seems to completely degrade traffic on the other. 

I need to figure out a way to test this more specifically.


>Do you have some kind of firewall running on the dom0 ?
>

Not on this host, although the outbound gateway has a standard npf(7) NAT.