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Re: [Xen-users] Slow upstream speeds from guest OS

Enable the PV network driver as Seffan said. Also can you tell us a little bit about your networking setup? Are you using an ethernet bridge (where the physical and guest interfaces are both slaves of the bridge), layer 3 routing, NAT, wireless proxy ARP, or something else? Post the output of `ip link` in the guest and host. Check for packet loss using ping or by comparing the in/out byte count of the guest and host[0]. If relevant, post your firewall rules using `iptables {,-tnat} -L -v` or `nft list ruleset`. Also, make sure your DomU has equal or better resources (memory, vcpus) than your Dom0 (or whatever domain you're testing against).

Also, consider setting up a driver domain[1]. Driver domains are good for security and reliability if you have an IOMMU, and can be good for performance in many cases, particularly when the Dom0 is CPU- or memory-bound by DomU excessive I/O. It also allows you to choose a different OS (and therefore driver) for the network card, so you can use one that gives you better performance.

If you only need networking in one guest, you can use PCI/USB passthrough which usually offers the best performance.

[0]: https://serverfault.com/questions/533513/how-to-get-tx-rx-bytes-without-ifconfig
[1]: http://wiki.xenproject.org/wiki/Driver_Domain

Quoting Wei Liu <wei.liu2@xxxxxxxxxx>:

On Mon, Feb 15, 2016 at 06:08:19PM -0700, Steffan Cline wrote:

Running into an odd thing and not sure where to look.

When I log into my CentOS 6 host OS and use the speediest-cli tool (https://github.com/sivel/speedtest-cli) I can get 20mbps up.

When I log into my CentOS 6 guest OS and use the same tool, I can only get about 2.5-5mbps up.

Any suggestions as to where to look for the cause of this horrid upstream?

Download speeds are only off by about 2mbps.

In the .cfg files, there are no limits imposed anywhere.

Please make sure your guest has PV network driver installed and

You can probably check that by "lsmod | grep netfront", provided the
driver is compiled as module (which most distros do).


Thank you,
Steffan Cline

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