From: Guenter Roeck <linux@roeck-us•net>
To: Andrew Lunn <andrew@lunn•ch>
Cc: Scott Feldman <sfeldma@gmail•com>,
roopa <roopa@cumulusnetworks•com>,
Viswanath Bandaru <vbandaru@broadcom•com>,
Florian Fainelli <f.fainelli@gmail•com>,
"netdev@vger•kernel.org" <netdev@vger•kernel.org>,
"jiri@resnulli•us" <jiri@resnulli•us>,
"gospo@cumulusnetworks•com" <gospo@cumulusnetworks•com>,
"siva.mannem.lnx@gmail•com" <siva.mannem.lnx@gmail•com>
Subject: Re: [PATCH net-next RFC 0/5] Add NTF_EXT_AGED to control FDB ageing in SW or HW
Date: Wed, 25 Feb 2015 08:43:03 -0800 [thread overview]
Message-ID: <20150225164303.GC25241@roeck-us.net> (raw)
In-Reply-To: <20150225143113.GD17992@lunn.ch>
On Wed, Feb 25, 2015 at 03:31:13PM +0100, Andrew Lunn wrote:
> > Geunter had this question in the thread:
> >
> > "I may be missing something, but I don't immediately see how this patch set
> > helps me solve any of the problems I am seeing when integrating the Marvell
> > switch code. Even if the switch internally does hardware aging, it still
> > seems to me that we'll need software aging on top of that, even if the
> > bridge code in the kernel has the same addresses in its fdb as the switch.
> > I see no feasible means to keep the fdb in the switch synchronized
> > with the fdb in the kernel".
> >
> > You'll want to turn learning off on the bridge, and enable learning (and
> > learning_sync) in hardware. The hw driver will install an FDB entry in the
> > bridge's FDB and mark it "external". The entry will also appear in the
> > device's FDB.
>
> I don't think this is going to work. There is no efficient way to get
> the hardware tables out of the hardware. We don't get notification of
> additions or removals. We can only read the whole table. And it can be
> expensive to read the whole table, since it can be 1K or more entries,
> going over an MDIO bus, which in the worst case can be bit banging on
> gpio lines.
>
Which, coincidentially, is the case in my application. The newer
Marvell switches support up to 8k forwarding table entries, so that
would be really awkward.
> We probably need a design for devices where we can efficiently get
> access to the hardware table, and use it in the software bridge. But
> we also need a design where the SW and HW bridges have independently
> tables.
>
Agreed.
Some of the Marvell chip support accessing its registers through Ethernet,
so that may be an option. That is not supported on all chips, so it would
not be a generic solution, but it may be worthwhile looking into.
Guenter
next prev parent reply other threads:[~2015-02-25 16:43 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-20 7:09 [PATCH net-next RFC 0/5] Add NTF_EXT_AGED to control FDB ageing in SW or HW sfeldma
2015-02-20 7:09 ` [PATCH net-next RFC 1/5] neighbour: add external aged flag sfeldma
2015-02-20 7:09 ` [PATCH net-next RFC 2/5] switchdev: add ntf_flags to FDB notifier sfeldma
2015-02-20 7:09 ` [PATCH net-next RFC 3/5] bridge: call external learn add if adding FDB entry with NTF_EXT_LEARNED set sfeldma
2015-02-20 7:09 ` [PATCH net-next RFC 4/5] bridge: let HW control FDB ageing by setting NTF_EXT_AGED sfeldma
2015-02-20 17:31 ` David Miller
2015-02-20 7:09 ` [PATCH net-next RFC 5/5] rocker: explicitly set SW ageing for rocker sfeldma
2015-02-20 9:46 ` Jiri Pirko
2015-02-20 14:56 ` Scott Feldman
2015-02-20 17:29 ` [PATCH net-next RFC 0/5] Add NTF_EXT_AGED to control FDB ageing in SW or HW roopa
2015-02-20 19:13 ` Florian Fainelli
2015-02-20 19:45 ` Guenter Roeck
2015-02-21 0:20 ` Viswanath Bandaru
2015-02-21 0:39 ` Guenter Roeck
2015-02-21 18:29 ` roopa
[not found] ` <CAE4R7bAPS1GZKaC4M6x9cqfTOkVju1+Po4KzanfSniEFX9oi1w@mail.gmail.com>
2015-02-25 14:31 ` Andrew Lunn
2015-02-25 16:43 ` Guenter Roeck [this message]
2015-02-25 17:31 ` B Viswanath
2015-02-25 18:39 ` Guenter Roeck
2015-02-25 18:51 ` B Viswanath
2015-02-25 19:15 ` Guenter Roeck
2015-02-25 19:33 ` B Viswanath
2015-02-25 20:03 ` Guenter Roeck
2015-02-25 17:29 ` David Miller
2015-02-21 11:03 ` Jiri Pirko
2015-02-21 11:29 ` Viswanath Bandaru
2015-02-21 15:50 ` Jiri Pirko
2015-02-21 17:20 ` Viswanath Bandaru
2015-02-21 18:31 ` roopa
2015-02-21 1:23 ` Siva Mannem
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