Re: [dpdk-dev] QoS Question

[Sangjin Han <sangjin@eecs.berkeley.edu>]

Hi,

According to "21.2.4.6.6.2", it seems that the implementation is supposed
to achieve max-min fairness. In your example, the effective cap of single
active pipe should be 1Mbps, given the total demand of other 1999 pipes is
less than 999Mbps.

Sangjin

On Mon, Apr 20, 2015 at 9:40 AM Greg Smith <gregsmith@juniper.net> wrote:

> Hi DPDK team,
>
> The docs on QoS (http://dpdk.org/doc/guides/prog_guide/qos_framework.html#
> ) describe the traffic class (TC) as follows:
> 1 - The  TCs of the same pipe handled in strict priority order.
> 2 - Upper limit enforced per TC at the pipe level.
> 3 - Lower priority TCs able to reuse pipe bandwidth currently unused by
> higher priority TCs.
> 4 - When subport TC is oversubscribed (configuration time event), pipe TC
> upper limit is capped to a dynamically adjusted value that is shared by all
> the subport pipes.
>
> Can someone describe how and when the TC upper limit is "dynamically"
> changed?
>
> For example, assume there's a 1Gb/s port and a single 1Gb/s subport and
> 2000 pipes each of 1Mb/s (total pipes = 2Gb/s which is > the 1Gb/s subport
> which I think means "oversubscribed" as used in the doc). Each Pipe has a
> single TC.
> In that case, would each pipe be shaped to an upper limit of 0.5 Mb/s?
> What if there was no traffic on 1999 pipes, would the single active pipe
> still be limited to 0.5 Mb/s?
> What if the number of pipes changes without restarting the OS, how does
> that change the behavior?
>
> BTW, great docs overall, thanks for writing those up.
>
> Thanks,
>
> Greg Smith
>
>
>
>