Re: [PATCH net-next] net: dpaa_eth: convert to napi_gro_receive

[Rosen Penev]

On Mon, Jul 6, 2026 at 1:39 AM Vladimir Oltean <olteanv@xxxxxxxxx> wrote:
>
> Hi Rosen,
>
> On Sun, Jul 05, 2026 at 08:06:32PM -0700, Rosen Penev wrote:
> > Replace netif_receive_skb() with napi_gro_receive() to improve receive
> > performance for this driver. It has rx checksum support so routing speed
> > shouldn't suffer.
> >
> > Tested on a WatchGuard Firebox M300.
> >
> > iperf3 bidir speed test:
> >
> > [ ID][Role]   Interval         Transfer      Bitrate        Retr
> > [  5][TX-C]   0.00-60.01  sec  5.35 GBytes   766 Mbits/sec  184    sender
> > [  5][TX-C]   0.00-60.02  sec  5.35 GBytes   766 Mbits/sec         receiver
> > [  7][RX-C]   0.00-60.01  sec  5.50 GBytes   787 Mbits/sec  124    sender
> > [  7][RX-C]   0.00-60.02  sec  5.49 GBytes   786 Mbits/sec         receiver
> >
> > After:
> >
> > [ ID][Role]   Interval         Transfer      Bitrate        Retr
> > [  5][TX-C]   0.00-60.01  sec  6.49 GBytes   929 Mbits/sec    0    sender
> > [  5][TX-C]   0.00-60.02  sec  6.49 GBytes   928 Mbits/sec         receiver
> > [  7][RX-C]   0.00-60.01  sec  6.55 GBytes   938 Mbits/sec    0    sender
> > [  7][RX-C]   0.00-60.02  sec  6.55 GBytes   937 Mbits/sec         receiver
> >
> > Assisted-by: Opencode:big-pickle
> > Signed-off-by: Rosen Penev <rosenp@xxxxxxxxx>
> > ---
> >  drivers/net/ethernet/freescale/dpaa/dpaa_eth.c | 5 +----
> >  1 file changed, 1 insertion(+), 4 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> > index ad2d8256eb8d..83191f636ec7 100644
> > --- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> > +++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> > @@ -2824,10 +2824,7 @@ static enum qman_cb_dqrr_result rx_default_dqrr(struct qman_portal *portal,
> >
> >       skb_len = skb->len;
> >
> > -     if (unlikely(netif_receive_skb(skb) == NET_RX_DROP)) {
> > -             percpu_stats->rx_dropped++;
> > -             return qman_cb_dqrr_consume;
> > -     }
> > +     napi_gro_receive(&np->napi, skb);
> >
> >       percpu_stats->rx_packets++;
> >       percpu_stats->rx_bytes += skb_len;
> > --
> > 2.55.0
> >
> >
>
> (thanks to Madalin for pointing out this change to me)
>
> I do not have time this week to test this patch, but in premise, you are
> creating exactly the conditions for this bug to occur:
> https://github.com/nxp-qoriq/linux/commit/d0ebec2092d6c5fe327513cb66e02d8c2c1a8f87
>
> In sdk_dpaa we already do GRO for TCP flows and it has the problems
> pointed out in the above commit. With your change to use GRO for all
> capable flows, I currently have no reason to believe that without
> similar countermeasures as those taken by sdk_dpaa (napi_gro_receive()
> global to the entire QMan portal) the outcome would be different.
>
> Have you tested traffic in mixed scenarios, where flows from multiple
> interfaces land on the same CPU?
Just iperf3 --bidir.
>
> Until further evidence comes in:
Maybe netif_receive_skb_list is a better fit here.
>
> pw-bot: cr