netdev - Re: [PATCH net-next 1/3] net:dsa:mv88e6xxx: use hashtable to store multicast entries

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Date:   Thu, 15 Dec 2016 12:21:18 -0500
From:   Vivien Didelot <vivien.didelot@...oirfairelinux.com>
To:     Volodymyr Bendiuga <volodymyr.bendiuga@...il.com>,
        Andrew Lunn <andrew@...n.ch>
Cc:     Volodymyr Bendiuga <valdr.linuxnext@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        netdev@...r.kernel.org,
        Volodymyr Bendiuga <volodymyr.bendiuga@...termo.se>,
        John Crispin <john@...ozen.org>
Subject: Re: [PATCH net-next 1/3] net:dsa:mv88e6xxx: use hashtable to store multicast entries

Hi Volodymyr,

Volodymyr Bendiuga <volodymyr.bendiuga@...il.com> writes:

> Hi Andrew,
>
> I have tested the approach you wrote in previous mails, the one
> with setting next.mac to address we are looking for -1. It seems
> to be as slow as the original implementation, unfortunately.

Hum, that is what I was expecting... The ATU GetNext operation
(alongside an ether_addr_equal() call) should be quite fast.

> We use 6097 and 6352 chips, and both of them can not do any port
> filtering in hardware for fdb dump operation. Seems like they would
> benefit from cache. But I am not sure about other switches.
>
> Does anyone know about such feature in other switches?

Marvell switches cannot filter ATU entries for a specific port, they
contain a port vector.

I guess Florian might answer for Broadcom switches, and John might
answer for Qualcomm switches.

In all cases *if caching is really needed*, I think it won't hurt to do
it in DSA core even if a switch support FDB dump operations on a
per-port basis, as Andrew mentioned.

Thanks,

        Vivien