netdev - Re: [PATCH net v2 3/3] octeontx2-pf: Do xdp_do

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Message-ID: <f5832f155f3daff50b0e7ea94fee84d3a70e4f29.camel@redhat.com>
Date: Thu, 21 Sep 2023 09:01:16 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: Kui-Feng Lee <sinquersw@...il.com>, Sebastian Andrzej Siewior
	 <bigeasy@...utronix.de>, netdev@...r.kernel.org, bpf@...r.kernel.org
Cc: "David S. Miller" <davem@...emloft.net>, Alexei Starovoitov
 <ast@...nel.org>,  Daniel Borkmann <daniel@...earbox.net>, Eric Dumazet
 <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,  Jesper Dangaard
 Brouer <hawk@...nel.org>, John Fastabend <john.fastabend@...il.com>, Thomas
 Gleixner <tglx@...utronix.de>, Geetha sowjanya <gakula@...vell.com>,
 Subbaraya Sundeep <sbhatta@...vell.com>, Sunil Goutham
 <sgoutham@...vell.com>, hariprasad <hkelam@...vell.com>
Subject: Re: [PATCH net v2 3/3] octeontx2-pf: Do xdp_do_flush() after
 redirects.

On Mon, 2023-09-18 at 10:58 -0700, Kui-Feng Lee wrote:
> 
> On 9/18/23 08:36, Sebastian Andrzej Siewior wrote:
> > xdp_do_flush() should be invoked before leaving the NAPI poll function
> > if XDP-redirect has been performed.
> > 
> > Invoke xdp_do_flush() before leaving NAPI.
> > 
> > Cc: Geetha sowjanya <gakula@...vell.com>
> > Cc: Subbaraya Sundeep <sbhatta@...vell.com>
> > Cc: Sunil Goutham <sgoutham@...vell.com>
> > Cc: hariprasad <hkelam@...vell.com>
> > Fixes: 06059a1a9a4a5 ("octeontx2-pf: Add XDP support to netdev PF")
> > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
> > Acked-by: Geethasowjanya Akula <gakula@...vell.com>
> > ---
> >   .../marvell/octeontx2/nic/otx2_txrx.c         | 19 +++++++++++++------
> >   1 file changed, 13 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c
> > index e77d438489557..53b2a4ef52985 100644
> > --- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c
> > +++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c
> > @@ -29,7 +29,8 @@
> >   static bool otx2_xdp_rcv_pkt_handler(struct otx2_nic *pfvf,
> >   				     struct bpf_prog *prog,
> >   				     struct nix_cqe_rx_s *cqe,
> > -				     struct otx2_cq_queue *cq);
> > +				     struct otx2_cq_queue *cq,
> > +				     bool *need_xdp_flush);
> >   
> >   static int otx2_nix_cq_op_status(struct otx2_nic *pfvf,
> >   				 struct otx2_cq_queue *cq)
> > @@ -337,7 +338,7 @@ static bool otx2_check_rcv_errors(struct otx2_nic *pfvf,
> >   static void otx2_rcv_pkt_handler(struct otx2_nic *pfvf,
> >   				 struct napi_struct *napi,
> >   				 struct otx2_cq_queue *cq,
> > -				 struct nix_cqe_rx_s *cqe)
> > +				 struct nix_cqe_rx_s *cqe, bool *need_xdp_flush)
> >   {
> >   	struct nix_rx_parse_s *parse = &cqe->parse;
> >   	struct nix_rx_sg_s *sg = &cqe->sg;
> > @@ -353,7 +354,7 @@ static void otx2_rcv_pkt_handler(struct otx2_nic *pfvf,
> >   	}
> >   
> >   	if (pfvf->xdp_prog)
> > -		if (otx2_xdp_rcv_pkt_handler(pfvf, pfvf->xdp_prog, cqe, cq))
> > +		if (otx2_xdp_rcv_pkt_handler(pfvf, pfvf->xdp_prog, cqe, cq, need_xdp_flush))
> >   			return;
> >   
> >   	skb = napi_get_frags(napi);
> > @@ -388,6 +389,7 @@ static int otx2_rx_napi_handler(struct otx2_nic *pfvf,
> >   				struct napi_struct *napi,
> >   				struct otx2_cq_queue *cq, int budget)
> >   {
> > +	bool need_xdp_flush = false;
> >   	struct nix_cqe_rx_s *cqe;
> >   	int processed_cqe = 0;
> >   
> > @@ -409,13 +411,15 @@ static int otx2_rx_napi_handler(struct otx2_nic *pfvf,
> >   		cq->cq_head++;
> >   		cq->cq_head &= (cq->cqe_cnt - 1);
> >   
> > -		otx2_rcv_pkt_handler(pfvf, napi, cq, cqe);
> > +		otx2_rcv_pkt_handler(pfvf, napi, cq, cqe, &need_xdp_flush);
> >   
> >   		cqe->hdr.cqe_type = NIX_XQE_TYPE_INVALID;
> >   		cqe->sg.seg_addr = 0x00;
> >   		processed_cqe++;
> >   		cq->pend_cqe--;
> >   	}
> > +	if (need_xdp_flush)
> > +		xdp_do_flush();
> >   
> >   	/* Free CQEs to HW */
> >   	otx2_write64(pfvf, NIX_LF_CQ_OP_DOOR,
> > @@ -1354,7 +1358,8 @@ bool otx2_xdp_sq_append_pkt(struct otx2_nic *pfvf, u64 iova, int len, u16 qidx)
> >   static bool otx2_xdp_rcv_pkt_handler(struct otx2_nic *pfvf,
> >   				     struct bpf_prog *prog,
> >   				     struct nix_cqe_rx_s *cqe,
> > -				     struct otx2_cq_queue *cq)
> > +				     struct otx2_cq_queue *cq,
> > +				     bool *need_xdp_flush)
> >   {
> >   	unsigned char *hard_start, *data;
> >   	int qidx = cq->cq_idx;
> > @@ -1391,8 +1396,10 @@ static bool otx2_xdp_rcv_pkt_handler(struct otx2_nic *pfvf,
> >   
> >   		otx2_dma_unmap_page(pfvf, iova, pfvf->rbsize,
> >   				    DMA_FROM_DEVICE);
> > -		if (!err)
> > +		if (!err) {
> > +			*need_xdp_flush = true;
> 
> Is it possible to call xdp_do_flush() at the first place (here)?

AFAICT that would kill much/all of the performance benefits of bulk
redirect.

I think the proposed solution is a better one.

Cheers,

Paolo