Re: [PATCH net-next 2/3] net: ethernet: ti: cpsw_new: enable broadcast/multicast rate limit support

[Grygorii Strashko]

On 14/11/2020 21:09, Vladimir Oltean wrote:
> On Sat, Nov 14, 2020 at 05:56:53AM +0200, Grygorii Strashko wrote:
> > This patch enables support for ingress broadcast(BC)/multicast(MC) rate limiting
> > in TI CPSW switchdev driver (the corresponding ALE support was added in previous
> > patch) by implementing HW offload for simple tc-flower policer with matches
> > on dst_mac:
> >   - ff:ff:ff:ff:ff:ff has to be used for BC rate limiting
> >   - 01:00:00:00:00:00 fixed value has to be used for MC rate limiting
> >
> > Hence tc policer defines rate limit in terms of bits per second, but the
> > ALE supports limiting in terms of packets per second - the rate limit
> > bits/sec is converted to number of packets per second assuming minimum
> > Ethernet packet size ETH_ZLEN=60 bytes.
> >
> > Examples:
> > - BC rate limit to 1000pps:
> >    tc qdisc add dev eth0 clsact
> >    tc filter add dev eth0 ingress flower skip_sw dst_mac ff:ff:ff:ff:ff:ff \
> >    action police rate 480kbit burst 64k
> >
> >    rate 480kbit - 1000pps * 60 bytes * 8, burst - not used.
> >
> > - MC rate limit to 20000pps:
> >    tc qdisc add dev eth0 clsact
> >    tc filter add dev eth0 ingress flower skip_sw dst_mac 01:00:00:00:00:00 \
> >    action police rate 9600kbit burst 64k
> >
> >    rate 9600kbit - 20000pps * 60 bytes * 8, burst - not used.
> >
> > Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx>
> > ---
>
> Your example for multicast would actually be correct if you specified
> the mask as well. Like this:
>
> tc filter add dev eth0 ingress flower skip_sw \
> 	dst_mac 01:00:00:00:00:00/01:00:00:00:00:00 \
> 	action police rate 9600kbit burst 64k
>
> But as things stand, the flow rule would have a certain meaning in
> software (rate-limit only that particular multicast MAC address) and a
> different meaning in hardware. Please modify the driver code to also
> match on the mask.

ok.

--
Best regards,
grygorii