On 4/10/17, 2:30 AM, "ovs-discuss-boun...@openvswitch.org on behalf of O
Mahony, Billy" <ovs-discuss-boun...@openvswitch.org on behalf of
billy.o.mah...@intel.com> wrote:
Hi Everybody,
I just wanted to reflag this discussion below about possible methods of how
to prioritize certain types of traffic handled by OVS.
By prioritize I mean either or both of:
a) 'priority' packets are sent to their destination port faster than other
packets
For scheduling priority, there is api support thru. other_config : priority at
the queue level
QoS type would be htb in this case
Main code is in netdev-linux.c
Uses tc under the hood, so there is dependency on tc and beyond.
Queues so defined are referenced thru set_queue actions as usual.
I have not tried it…
b) in an overloaded situation the switch drops non-prioritized packets
rather than prioritized packets.
Maybe you are referring to RED types of approaches
I don’t know of any hooks or even how good the Linux base support is.
Hopefully others have some exposure.
Also just to be clear I am discussing kernel ovs here. Also I'm looking at
doing this without writing new code - ie is it possible and if so how is it
configured using existing OVS.
Thanks again,
Billy.
> -----Original Message-----
> From: ovs-discuss-boun...@openvswitch.org [mailto:ovs-discuss-
> boun...@openvswitch.org] On Behalf Of O Mahony, Billy
> Sent: Friday, November 25, 2016 5:04 PM
> To: ovs-discuss@openvswitch.org
> Subject: [ovs-discuss] prioritizing latency-sensitive traffic
>
> Hi,
>
> I have been performing tests investigating latency profiles of
low-bandwidth
> time-sensitive traffic when the system is busy with 'normal' traffic.
> Unsurprisingly the latency-sensitive traffic is affected by the normal
traffic
> and has basically the same latency profile as the normal traffic.
>
> I would like to be able to perform prioritization of traffic as some
protocols
> such as PTP would benefit greatly from having it's packets 'jump the
queue'.
>
> From skimming the documentation it looks that ingress QoS offers only
> policing (rate-limiting). Is this actually the case or maybe I'm not
looking in the
> right place?
>
> But if so, I am looking at some alternatives:
>
> a) create two separate egress ports and have PTP listen on one port,
> everything else listen on the other port and use normal forwarding rules
to
> send PTP traffic incoming from eth0 to it's own port. Something like:
>
> other apps ptp_daemon
> + +
> + +
> if_norm if_ptp
> + +
> | |
> | |
> ++------------++
> | |
> | ovs |
> | |
> +-----+--------+
> |
> +
> eth0
>
> b) create prioritized queues on a port and use match and actions such as
> set_queue(queue) and enqueue(port, queue) on ingress traffic to forward
> the PTP traffic to the higher priority queue. However I think queue
priority
> for this case only relates to which queue get to consume the bandwidth of
> the port first and not about changing the order in which the packets
egress
> the port.
>
> c) Or perhaps I can re-use tc PRIO or CBQ qdiscs by passing all traffic
to tc first
> before ovs?
>
> other apps
> |
> |
> if_norm
> +
> |
> |
> +--------------+
> | |
> | ovs |
> | |
> +-----+--------+
> |
> |
> tc ----- if_ptp ---- ptp_daemon
> +
> eth0
>
> Any thoughts, ideas or clarifications most welcome.
>
> Thanks,
> Billy.
>
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