Re: [PATCH net-next v3 3/4] net: ocelot: pre-compute injection frame header content

[Clément Léger]

Le Fri, 26 Nov 2021 17:54:55 +0000,
Vladimir Oltean <vladimir.oltean@xxxxxxx> a écrit :

> On Fri, Nov 26, 2021 at 06:27:38PM +0100, Clément Léger wrote:
> > IFH preparation can take quite some time on slow processors (up to 5% in
> > a iperf3 test for instance). In order to reduce the cost of this
> > preparation, pre-compute IFH since most of the parameters are fixed per
> > port. Only rew_op and vlan tag will be set when sending if different
> > than 0. This allows to remove entirely the calls to packing() with basic
> > usage. In the same time, export this function that will be used by FDMA.
> > 
> > Signed-off-by: Clément Léger <clement.leger@xxxxxxxxxxx>
> > ---  
> 
> If you would move this injection frame header template into struct
> ocelot_port_private instead of struct ocelot_port, I would not have
> anything against it. Because struct ocelot_port is common with DSA,
> whereas struct ocelot_port_private isn't.
> 
> Also, as things stand, all switch drivers call ocelot_init_port, but not
> all supported switches have the same IFH format. See seville_xmit() ->
> seville_ifh_set_dest(). So even though DSA does not use this for
> anything, it wouldn't even contain valid information even if it wanted
> to. So maybe you can move this initialization to some place isolated to
> vsc7514.

Acked, this makes sense, I will do this.

-- 
Clément Léger,
Embedded Linux and Kernel engineer at Bootlin
https://bootlin.com