netdev - Re: [PATCH net-next v3 5/7] net: axienet: implement NAPI and GRO receive

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Date:   Tue, 8 Mar 2022 21:13:44 +0000
From:   Robert Hancock <robert.hancock@...ian.com>
To:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "jwiedmann.dev@...il.com" <jwiedmann.dev@...il.com>
CC:     "linux@...linux.org.uk" <linux@...linux.org.uk>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "michal.simek@...inx.com" <michal.simek@...inx.com>,
        "radhey.shyam.pandey@...inx.com" <radhey.shyam.pandey@...inx.com>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH net-next v3 5/7] net: axienet: implement NAPI and GRO
 receive

On Mon, 2022-03-07 at 08:53 +0200, Julian Wiedmann wrote:
> On 05.03.22 04:24, Robert Hancock wrote:
> > Implement NAPI and GRO receive. In addition to better performance, this
> > also avoids handling RX packets in hard IRQ context, which reduces the
> > IRQ latency impact to other devices.
> > 
> > Signed-off-by: Robert Hancock <robert.hancock@...ian.com>
> > ---
> >  drivers/net/ethernet/xilinx/xilinx_axienet.h  |  6 ++
> >  .../net/ethernet/xilinx/xilinx_axienet_main.c | 81 ++++++++++++-------
> >  2 files changed, 59 insertions(+), 28 deletions(-)
> > 
> 
> [...]
> 
> > -static void axienet_recv(struct net_device *ndev)
> > +static int axienet_poll(struct napi_struct *napi, int budget)
> >  {
> >  	u32 length;
> >  	u32 csumstatus;
> >  	u32 size = 0;
> > -	u32 packets = 0;
> > +	int packets = 0;
> >  	dma_addr_t tail_p = 0;
> > -	struct axienet_local *lp = netdev_priv(ndev);
> > -	struct sk_buff *skb, *new_skb;
> >  	struct axidma_bd *cur_p;
> > +	struct sk_buff *skb, *new_skb;
> > +	struct axienet_local *lp = container_of(napi, struct axienet_local,
> > napi);
> >  
> >  	cur_p = &lp->rx_bd_v[lp->rx_bd_ci];
> >  
> > -	while ((cur_p->status & XAXIDMA_BD_STS_COMPLETE_MASK)) {
> > +	while (packets < budget && (cur_p->status &
> > XAXIDMA_BD_STS_COMPLETE_MASK)) {
> >  		dma_addr_t phys;
> >  
> >  		/* Ensure we see complete descriptor update */
> > @@ -918,7 +916,7 @@ static void axienet_recv(struct net_device *ndev)
> >  					 DMA_FROM_DEVICE);
> >  
> >  			skb_put(skb, length);
> > -			skb->protocol = eth_type_trans(skb, ndev);
> > +			skb->protocol = eth_type_trans(skb, lp->ndev);
> >  			/*skb_checksum_none_assert(skb);*/
> >  			skb->ip_summed = CHECKSUM_NONE;
> >  
> > @@ -937,13 +935,13 @@ static void axienet_recv(struct net_device *ndev)
> >  				skb->ip_summed = CHECKSUM_COMPLETE;
> >  			}
> >  
> > -			netif_rx(skb);
> > +			napi_gro_receive(napi, skb);
> >  
> >  			size += length;
> >  			packets++;
> >  		}
> >  
> > -		new_skb = netdev_alloc_skb_ip_align(ndev, lp->max_frm_size);
> > +		new_skb = netdev_alloc_skb_ip_align(lp->ndev, lp-
> > >max_frm_size);
> >  		if (!new_skb)
> >  			break;
> >  
> 
> Here you should be able to use napi_alloc_skb() now instead.

Thanks - this patch set was merged to net-next already, but I just submitted a
follow-on patch to add in this change.

-- 
Robert Hancock
Senior Hardware Designer, Calian Advanced Technologies
www.calian.com