linux-kernel - Re: [EXT] Re: [PATCH net-next 3/5] net: mvpp2: cls: Use RSS contexts to handle RSS tables

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Date:   Sat, 9 May 2020 14:16:19 +0200
From:   Matteo Croce <mcroce@...hat.com>
To:     Stefan Chulski <stefanc@...vell.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        Maxime Chevallier <maxime.chevallier@...tlin.com>,
        netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Antoine Tenart <antoine.tenart@...tlin.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        "gregory.clement@...tlin.com" <gregory.clement@...tlin.com>,
        "miquel.raynal@...tlin.com" <miquel.raynal@...tlin.com>,
        Nadav Haklai <nadavh@...vell.com>,
        Marcin Wojtas <mw@...ihalf.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Russell King - ARM Linux admin <linux@...linux.org.uk>
Subject: Re: [EXT] Re: [PATCH net-next 3/5] net: mvpp2: cls: Use RSS contexts
 to handle RSS tables

On Sat, May 9, 2020 at 1:16 PM Stefan Chulski <stefanc@...vell.com> wrote:
> > Hi,
> >
> > What do you think about temporarily disabling it like this?
> >
> > --- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> > +++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> > @@ -5775,7 +5775,8 @@ static int mvpp2_port_probe(struct platform_device
> > *pdev,
> >                             NETIF_F_HW_VLAN_CTAG_FILTER;
> >
> >         if (mvpp22_rss_is_supported()) {
> > -               dev->hw_features |= NETIF_F_RXHASH;
> > +               if (port->phy_interface != PHY_INTERFACE_MODE_SGMII)
> > +                       dev->hw_features |= NETIF_F_RXHASH;
> >                 dev->features |= NETIF_F_NTUPLE;
> >         }
> >
> >
> > David, is this "workaround" too bad to get accepted?
>
> Not sure that RSS related to physical interface(SGMII), better just remove NETIF_F_RXHASH as "workaround".
>
> Stefan.

Hi,

The point is that RXHASH works fine on all interfaces, but on the
gigabit one (eth2 usually).
And on the 10 gbit interface is very very effective, the throughput
goes 4x when enabled, so it would be a big drawback to disable it on
all interfaces.

Honestly I don't have any 2.5 gbit hardware to test it on eth3, so I
don't know if rxhash actually only works on the first interface of a
unit (so eth0 and eth1),
or if it just doesn't work on the gigabit one.

If someone could test it on the 2.5 gbit port, this will be helpful.

Regards,
-- 
Matteo Croce
per aspera ad upstream