On Fri, Dec 14, 2018 at 05:53:05PM +0500, Ramzah Rehman wrote:
> I have two servers connected via 1Gbps cable. I have installed OVS 2.8 on
> server one. I have a switch named OVS_BR_LEAF_1 on it. I experimented with
> QoS traffic shaping. I have connected eth3 of server one to ovs-switch on
> port 2. I want traffic going from server one to server two to observer QoS
> traffic rate that I specify.
>
> I added following configuration:
>
> #ovs-vsctl -- set port eth3 qos=@newqos -- --id=@newqos create qos
> type=linux-hfsc other-config:max-rate=1000000000 queues:1=@q1 -- --id=@q1
> create queue other-config:min-rate=x other-config:max-rate=x
>
> I have following flow entries in my switch:
> #vs-ofctl add-flow OVS_BR_LEAF_1
> priority=6000,in_port=LOCAL,actions=set_queue:1,normal
> #ovs-ofctl add-flow OVS_BR_LEAF_1 priority=6000,in_port=2,actions=normal
>
> Then I checked throughput for TCP traffic (from server one to two) via
> iperf and got following results:
>
> got 846 Mbps for x=900 Mbps
> got 757 Mbps for x=800 Mbps
> got 653 Mbps for x=700 Mbps
> got 428 Mbps for x=450 Mbps
> got 381 Mbps for x=400 Mbps
> got 287 Mbps for x=300 Mbps
> got 239 Mbps for x=250 Mbps
> got 192 Mbps for x=200 Mbps
>
> Seems like traffic shaping is working fine for TCP traffic. However, for
> UDP, I got these results:
>
> 148 Mbps for x=800 Mbps
> 185 Mbps for x=300 Mbps
> 131 Mbps for x=200 Mbps
> 93 Mbps for x=100 Mbps
> 77 Mbps for x=80 Mbps
> 28.9 Mbps for x=30 Mbps
> 19.3 Mbps for x=20 Mbps
>
> For UDP, traffic shaping works fine till x=100Mpbs, but for higher values
> is shows unexpected behavior. Is there an explanation?
This FAQ entry probably applies.
Q: I configured QoS, correctly, but my measurements show that it isn't working
as well as I expect.
A: With the Linux kernel, the Open vSwitch implementation of QoS has two
aspects:
- Open vSwitch configures a subset of Linux kernel QoS features, according
to what is in OVSDB. It is possible that this code has bugs. If you
believe that this is so, then you can configure the Linux traffic control
(QoS) stack directly with the "tc" program. If you get better results
that way, you can send a detailed bug report to [email protected].
It is certain that Open vSwitch cannot configure every Linux kernel QoS
feature. If you need some feature that OVS cannot configure, then you
can also use "tc" directly (or add that feature to OVS).
- The Open vSwitch implementation of OpenFlow allows flows to be directed
to particular queues. This is pretty simple and unlikely to have serious
bugs at this point.
However, most problems with QoS on Linux are not bugs in Open vSwitch at
all. They tend to be either configuration errors (please see the earlier
questions in this section) or issues with the traffic control (QoS) stack
in Linux. The Open vSwitch developers are not experts on Linux traffic
control. We suggest that, if you believe you are encountering a problem
with Linux traffic control, that you consult the tc manpages (e.g. tc(8),
tc-htb(8), tc-hfsc(8)), web resources (e.g. http://lartc.org/), or mailing
lists (e.g. http://vger.kernel.org/vger-lists.html#netdev).
_______________________________________________
discuss mailing list
[email protected]
https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
