Slow networking speeds with Freebsd 12.0 and Xen-4.12.1, freebsd-12.0 as dom0

classic Classic list List threaded Threaded
5 messages Options
Reply | Threaded
Open this post in threaded view
|

Slow networking speeds with Freebsd 12.0 and Xen-4.12.1, freebsd-12.0 as dom0

Brian Buhrow
        Hello.  I'm noticing that network performance on guest VN's whether
they're pv or hvm is very slow when using FreeBSD-12.0 as dom0 as compared
with older versions of Xen and NetBSD as dom0.  For example,
I have the following two comparisons, both with the same domu running:

FreeBSD-12.0/Xen 4.12.1, 60 mbits/sec from the vm in question.

NetBSD-5.2/xen 3.3, 781 mbits/sec with the same vm as above.

The NetBSD installation is running single CPU for the dom0, with 4GB of
RAM, as opposed to FreeBSD, which is running 8GB of RAM and 4 CPU's.
By contrast, disk performance under FreeBSD using zfs zvols' as virtual
disks is quite fast.  

        As a work around, I tried turning on msi interrupt handling on dom0 on
FreeBSD, using msi=false on the xen command line at boot time, but that
only resulted in a panic from FreeBSD because it couldn't get enough disk
interrupts to mount the root filesystem.

        Has anyone else noticed this abysmal network performance with
FreeBSD-12 as dom0?
If so, has anyone come up with fixes?
-thanks
-Brian

_______________________________________________
[hidden email] mailing list
https://lists.freebsd.org/mailman/listinfo/freebsd-xen
To unsubscribe, send any mail to "[hidden email]"
Reply | Threaded
Open this post in threaded view
|

Re: Slow networking speeds with Freebsd 12.0 and Xen-4.12.1, freebsd-12.0 as dom0

Roger Pau Monné
On Thu, Feb 13, 2020 at 06:58:53PM -0800, Brian Buhrow wrote:
> Hello.  I'm noticing that network performance on guest VN's whether
> they're pv or hvm is very slow when using FreeBSD-12.0 as dom0 as compared
> with older versions of Xen and NetBSD as dom0.  For example,
> I have the following two comparisons, both with the same domu running:
>
> FreeBSD-12.0/Xen 4.12.1, 60 mbits/sec from the vm in question.

So I've done a small test and using a FreeBSD dom0 with a FreeBSD domU
in HVM mode and I get:

# iperf -c 192.168.1.150
------------------------------------------------------------
Client connecting to 192.168.1.150, TCP port 5001
TCP window size:  113 KByte (default)
------------------------------------------------------------
[  3] local 192.168.1.101 port 12224 connected with 192.168.1.150 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec   302 MBytes   253 Mbits/sec

This is using my macbook as an iperf server with a USB-ethernet
adapter (so not professional grade hardware at all).

I'm quite sure speed could be better, we certainly have quite a lot of
room for improvement regarding netfront/netback on FreeBSD, as no one
looked at it for quite some time.

Which OS are you using on the domU?

Can you paste the output of ifconfig from the domU? (I'm mostly
interested in knowing which features the domU is attempting to use)

Thanks, Roger.
_______________________________________________
[hidden email] mailing list
https://lists.freebsd.org/mailman/listinfo/freebsd-xen
To unsubscribe, send any mail to "[hidden email]"
Reply | Threaded
Open this post in threaded view
|

Re: Slow networking speeds with Freebsd 12.0 and Xen-4.12.1, freebsd-12.0 as dom0

Brian Buhrow
        hello Roger.  In building the tests for this e-mail, I think I
discovered the problem.  For the FreeBSD installation, I had guest_loglvl=all
loglvl=all on the xen command line.  When I turned that off and re-ran my
tests, the network performance on the FreeBSD system matches that of the
NetBSD system.  My apologies for the noise.
I'll perform some more tests and see how things progress.  I'm guessing,
however, that all will be well.
-thanks
-Brian

_______________________________________________
[hidden email] mailing list
https://lists.freebsd.org/mailman/listinfo/freebsd-xen
To unsubscribe, send any mail to "[hidden email]"
Reply | Threaded
Open this post in threaded view
|

Re: Slow networking speeds with Freebsd 12.0 and Xen-4.12.1, freebsd-12.0 as dom0

Brian Buhrow
        hello.  Ok.  Perhaps I spoke too soon!  the domu I was testing with,
which is an entirely pv guest, performs fine with FreeBSD.  However, if I
take an hvm guest and run that using Intel E1000 emulation, my performance
drops back to 70 mbits/sec or so of throughput.  For HVM guests, what kind
of network performance should I expect?  I've been running pv guests for
years, but don't have much experience with hvm guests.  
-thanks

_______________________________________________
[hidden email] mailing list
https://lists.freebsd.org/mailman/listinfo/freebsd-xen
To unsubscribe, send any mail to "[hidden email]"
Reply | Threaded
Open this post in threaded view
|

Re: Slow networking speeds with Freebsd 12.0 and Xen-4.12.1, freebsd-12.0 as dom0

Roger Pau Monné
On Fri, Feb 14, 2020 at 10:15:48AM -0800, Brian Buhrow wrote:
> hello.  Ok.  Perhaps I spoke too soon!  the domu I was testing with,
> which is an entirely pv guest, performs fine with FreeBSD.  However, if I
> take an hvm guest and run that using Intel E1000 emulation, my performance
> drops back to 70 mbits/sec or so of throughput.  For HVM guests, what kind
> of network performance should I expect?

That's hard to tell. My recommendation would be to try to install PV
drivers to HVM guests if possible in order to get better performance.
Performance of emulated nics is always going to be worse.

Is the QEMU process in dom0 consuming lots of CPU when using the
emulated nic?

> I've been running pv guests for
> years, but don't have much experience with hvm guests.  
> -thanks

Guests using PV devices (that applies to HVM/PVH guests also) should
always get better IO performance than those using emulated devices.

Thanks, Roger.
_______________________________________________
[hidden email] mailing list
https://lists.freebsd.org/mailman/listinfo/freebsd-xen
To unsubscribe, send any mail to "[hidden email]"