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Message-ID: <831968f6-3abb-6427-bb1a-e6fd40beb633@kernel.org> Date: Thu, 10 Aug 2023 16:11:41 +0200 From: Jesper Dangaard Brouer <hawk@...nel.org> To: Wei Fang <wei.fang@....com>, davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com, shenwei.wang@....com, xiaoning.wang@....com, ast@...nel.org, daniel@...earbox.net, hawk@...nel.org, john.fastabend@...il.com, larysa.zaremba@...el.com, aleksander.lobakin@...el.com, jbrouer@...hat.com, netdev@...r.kernel.org Cc: linux-imx@....com, linux-kernel@...r.kernel.org, bpf@...r.kernel.org Subject: Re: [PATCH V5 net-next 2/2] net: fec: improve XDP_TX performance On 10/08/2023 08.45, Wei Fang wrote: > As suggested by Jesper and Alexander, we can avoid converting xdp_buff > to xdp_frame in case of XDP_TX to save a bunch of CPU cycles, so that > we can further improve the XDP_TX performance. > > Before this patch on i.MX8MP-EVK board, the performance shows as follows. > root@...8mpevk:~# ./xdp2 eth0 > proto 17: 353918 pkt/s > proto 17: 352923 pkt/s > proto 17: 353900 pkt/s > proto 17: 352672 pkt/s > proto 17: 353912 pkt/s > proto 17: 354219 pkt/s > > After applying this patch, the performance is improved. > root@...8mpevk:~# ./xdp2 eth0 > proto 17: 369261 pkt/s > proto 17: 369267 pkt/s > proto 17: 369206 pkt/s > proto 17: 369214 pkt/s > proto 17: 369126 pkt/s > proto 17: 369272 pkt/s > So approx 4.3% improvement. > Signed-off-by: Wei Fang <wei.fang@....com> > Suggested-by: Alexander Lobakin <aleksander.lobakin@...el.com> > Suggested-by: Jesper Dangaard Brouer <hawk@...nel.org> > --- > V5 changes: > New patch. Separated from the first patch, to keep track of the changes > and improvements (suggested by Jesper). Thanks > --- > drivers/net/ethernet/freescale/fec.h | 5 +- > drivers/net/ethernet/freescale/fec_main.c | 134 ++++++++++++---------- > 2 files changed, 73 insertions(+), 66 deletions(-) > > diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h > index 7bb02a9da2a6..a8fbcada6b01 100644 > --- a/drivers/net/ethernet/freescale/fec.h > +++ b/drivers/net/ethernet/freescale/fec.h > @@ -552,10 +552,7 @@ enum fec_txbuf_type { > }; > > struct fec_tx_buffer { > - union { > - struct sk_buff *skb; > - struct xdp_frame *xdp; > - }; > + void *buf_p; I want to hear Olek's (Alexander) oppinion on this void pointer circus. The rest of the patch looks correct to me so: Reviewed-by: Jesper Dangaard Brouer <hawk@...nel.org> --Jesper > enum fec_txbuf_type type; > }; > > diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c > index 30b01985be7c..ae6e41ad71b8 100644 > --- a/drivers/net/ethernet/freescale/fec_main.c > +++ b/drivers/net/ethernet/freescale/fec_main.c > @@ -399,7 +399,7 @@ static void fec_dump(struct net_device *ndev) > fec16_to_cpu(bdp->cbd_sc), > fec32_to_cpu(bdp->cbd_bufaddr), > fec16_to_cpu(bdp->cbd_datlen), > - txq->tx_buf[index].skb); > + txq->tx_buf[index].buf_p); > bdp = fec_enet_get_nextdesc(bdp, &txq->bd); > index++; > } while (bdp != txq->bd.base); > @@ -656,7 +656,7 @@ static int fec_enet_txq_submit_skb(struct fec_enet_priv_tx_q *txq, > > index = fec_enet_get_bd_index(last_bdp, &txq->bd); > /* Save skb pointer */ > - txq->tx_buf[index].skb = skb; > + txq->tx_buf[index].buf_p = skb; > > /* Make sure the updates to rest of the descriptor are performed before > * transferring ownership. > @@ -862,7 +862,7 @@ static int fec_enet_txq_submit_tso(struct fec_enet_priv_tx_q *txq, > } > > /* Save skb pointer */ > - txq->tx_buf[index].skb = skb; > + txq->tx_buf[index].buf_p = skb; > > skb_tx_timestamp(skb); > txq->bd.cur = bdp; > @@ -959,27 +959,27 @@ static void fec_enet_bd_init(struct net_device *dev) > fec32_to_cpu(bdp->cbd_bufaddr), > fec16_to_cpu(bdp->cbd_datlen), > DMA_TO_DEVICE); > - if (txq->tx_buf[i].skb) { > - dev_kfree_skb_any(txq->tx_buf[i].skb); > - txq->tx_buf[i].skb = NULL; > - } > - } else { > - if (bdp->cbd_bufaddr && > - txq->tx_buf[i].type == FEC_TXBUF_T_XDP_NDO) > + if (txq->tx_buf[i].buf_p) > + dev_kfree_skb_any(txq->tx_buf[i].buf_p); > + } else if (txq->tx_buf[i].type == FEC_TXBUF_T_XDP_NDO) { > + if (bdp->cbd_bufaddr) > dma_unmap_single(&fep->pdev->dev, > fec32_to_cpu(bdp->cbd_bufaddr), > fec16_to_cpu(bdp->cbd_datlen), > DMA_TO_DEVICE); > > - if (txq->tx_buf[i].xdp) { > - xdp_return_frame(txq->tx_buf[i].xdp); > - txq->tx_buf[i].xdp = NULL; > - } > + if (txq->tx_buf[i].buf_p) > + xdp_return_frame(txq->tx_buf[i].buf_p); > + } else { > + struct page *page = txq->tx_buf[i].buf_p; > > - /* restore default tx buffer type: FEC_TXBUF_T_SKB */ > - txq->tx_buf[i].type = FEC_TXBUF_T_SKB; > + if (page) > + page_pool_put_page(page->pp, page, 0, false); > } > > + txq->tx_buf[i].buf_p = NULL; > + /* restore default tx buffer type: FEC_TXBUF_T_SKB */ > + txq->tx_buf[i].type = FEC_TXBUF_T_SKB; > bdp->cbd_bufaddr = cpu_to_fec32(0); > bdp = fec_enet_get_nextdesc(bdp, &txq->bd); > } > @@ -1386,6 +1386,8 @@ fec_enet_tx_queue(struct net_device *ndev, u16 queue_id, int budget) > struct netdev_queue *nq; > int index = 0; > int entries_free; > + struct page *page; > + int frame_len; > > fep = netdev_priv(ndev); > > @@ -1407,8 +1409,7 @@ fec_enet_tx_queue(struct net_device *ndev, u16 queue_id, int budget) > index = fec_enet_get_bd_index(bdp, &txq->bd); > > if (txq->tx_buf[index].type == FEC_TXBUF_T_SKB) { > - skb = txq->tx_buf[index].skb; > - txq->tx_buf[index].skb = NULL; > + skb = txq->tx_buf[index].buf_p; > if (bdp->cbd_bufaddr && > !IS_TSO_HEADER(txq, fec32_to_cpu(bdp->cbd_bufaddr))) > dma_unmap_single(&fep->pdev->dev, > @@ -1427,18 +1428,24 @@ fec_enet_tx_queue(struct net_device *ndev, u16 queue_id, int budget) > if (unlikely(!budget)) > break; > > - xdpf = txq->tx_buf[index].xdp; > - if (bdp->cbd_bufaddr && > - txq->tx_buf[index].type == FEC_TXBUF_T_XDP_NDO) > - dma_unmap_single(&fep->pdev->dev, > - fec32_to_cpu(bdp->cbd_bufaddr), > - fec16_to_cpu(bdp->cbd_datlen), > - DMA_TO_DEVICE); > + if (txq->tx_buf[index].type == FEC_TXBUF_T_XDP_NDO) { > + xdpf = txq->tx_buf[index].buf_p; > + if (bdp->cbd_bufaddr) > + dma_unmap_single(&fep->pdev->dev, > + fec32_to_cpu(bdp->cbd_bufaddr), > + fec16_to_cpu(bdp->cbd_datlen), > + DMA_TO_DEVICE); > + } else { > + page = txq->tx_buf[index].buf_p; > + } > + > bdp->cbd_bufaddr = cpu_to_fec32(0); > - if (unlikely(!xdpf)) { > + if (unlikely(!txq->tx_buf[index].buf_p)) { > txq->tx_buf[index].type = FEC_TXBUF_T_SKB; > goto tx_buf_done; > } > + > + frame_len = fec16_to_cpu(bdp->cbd_datlen); > } > > /* Check for errors. */ > @@ -1462,7 +1469,7 @@ fec_enet_tx_queue(struct net_device *ndev, u16 queue_id, int budget) > if (txq->tx_buf[index].type == FEC_TXBUF_T_SKB) > ndev->stats.tx_bytes += skb->len; > else > - ndev->stats.tx_bytes += xdpf->len; > + ndev->stats.tx_bytes += frame_len; > } > > /* Deferred means some collisions occurred during transmit, > @@ -1487,20 +1494,16 @@ fec_enet_tx_queue(struct net_device *ndev, u16 queue_id, int budget) > > /* Free the sk buffer associated with this last transmit */ > dev_kfree_skb_any(skb); > + } else if (txq->tx_buf[index].type == FEC_TXBUF_T_XDP_NDO) { > + xdp_return_frame_rx_napi(xdpf); > } else { > - if (txq->tx_buf[index].type == FEC_TXBUF_T_XDP_NDO) { > - xdp_return_frame_rx_napi(xdpf); > - } else { > - struct page *page = virt_to_head_page(xdpf->data); > - > - page_pool_put_page(page->pp, page, 0, true); > - } > - > - txq->tx_buf[index].xdp = NULL; > - /* restore default tx buffer type: FEC_TXBUF_T_SKB */ > - txq->tx_buf[index].type = FEC_TXBUF_T_SKB; > + page_pool_put_page(page->pp, page, 0, true); > } > > + txq->tx_buf[index].buf_p = NULL; > + /* restore default tx buffer type: FEC_TXBUF_T_SKB */ > + txq->tx_buf[index].type = FEC_TXBUF_T_SKB; > + > tx_buf_done: > /* Make sure the update to bdp and tx_buf are performed > * before dirty_tx > @@ -3230,7 +3233,6 @@ static void fec_enet_free_buffers(struct net_device *ndev) > { > struct fec_enet_private *fep = netdev_priv(ndev); > unsigned int i; > - struct sk_buff *skb; > struct fec_enet_priv_tx_q *txq; > struct fec_enet_priv_rx_q *rxq; > unsigned int q; > @@ -3255,18 +3257,23 @@ static void fec_enet_free_buffers(struct net_device *ndev) > kfree(txq->tx_bounce[i]); > txq->tx_bounce[i] = NULL; > > + if (!txq->tx_buf[i].buf_p) { > + txq->tx_buf[i].type = FEC_TXBUF_T_SKB; > + continue; > + } > + > if (txq->tx_buf[i].type == FEC_TXBUF_T_SKB) { > - skb = txq->tx_buf[i].skb; > - txq->tx_buf[i].skb = NULL; > - dev_kfree_skb(skb); > + dev_kfree_skb(txq->tx_buf[i].buf_p); > + } else if (txq->tx_buf[i].type == FEC_TXBUF_T_XDP_NDO) { > + xdp_return_frame(txq->tx_buf[i].buf_p); > } else { > - if (txq->tx_buf[i].xdp) { > - xdp_return_frame(txq->tx_buf[i].xdp); > - txq->tx_buf[i].xdp = NULL; > - } > + struct page *page = txq->tx_buf[i].buf_p; > > - txq->tx_buf[i].type = FEC_TXBUF_T_SKB; > + page_pool_put_page(page->pp, page, 0, false); > } > + > + txq->tx_buf[i].buf_p = NULL; > + txq->tx_buf[i].type = FEC_TXBUF_T_SKB; > } > } > } > @@ -3789,13 +3796,14 @@ fec_enet_xdp_get_tx_queue(struct fec_enet_private *fep, int index) > > static int fec_enet_txq_xmit_frame(struct fec_enet_private *fep, > struct fec_enet_priv_tx_q *txq, > - struct xdp_frame *frame, > - u32 dma_sync_len, bool ndo_xmit) > + void *frame, u32 dma_sync_len, > + bool ndo_xmit) > { > unsigned int index, status, estatus; > struct bufdesc *bdp; > dma_addr_t dma_addr; > int entries_free; > + u16 frame_len; > > entries_free = fec_enet_get_free_txdesc_num(txq); > if (entries_free < MAX_SKB_FRAGS + 1) { > @@ -3811,30 +3819,36 @@ static int fec_enet_txq_xmit_frame(struct fec_enet_private *fep, > index = fec_enet_get_bd_index(bdp, &txq->bd); > > if (ndo_xmit) { > - dma_addr = dma_map_single(&fep->pdev->dev, frame->data, > - frame->len, DMA_TO_DEVICE); > + struct xdp_frame *xdpf = frame; > + > + dma_addr = dma_map_single(&fep->pdev->dev, xdpf->data, > + xdpf->len, DMA_TO_DEVICE); > if (dma_mapping_error(&fep->pdev->dev, dma_addr)) > return -ENOMEM; > > + frame_len = xdpf->len; > + txq->tx_buf[index].buf_p = xdpf; > txq->tx_buf[index].type = FEC_TXBUF_T_XDP_NDO; > } else { > - struct page *page = virt_to_page(frame->data); > + struct xdp_buff *xdpb = frame; > + struct page *page; > > - dma_addr = page_pool_get_dma_addr(page) + sizeof(*frame) + > - frame->headroom; > + page = virt_to_page(xdpb->data); > + dma_addr = page_pool_get_dma_addr(page) + > + (xdpb->data - xdpb->data_hard_start); > dma_sync_single_for_device(&fep->pdev->dev, dma_addr, > dma_sync_len, DMA_BIDIRECTIONAL); > + frame_len = xdpb->data_end - xdpb->data; > + txq->tx_buf[index].buf_p = page; > txq->tx_buf[index].type = FEC_TXBUF_T_XDP_TX; > } > > - txq->tx_buf[index].xdp = frame; > - > status |= (BD_ENET_TX_INTR | BD_ENET_TX_LAST); > if (fep->bufdesc_ex) > estatus = BD_ENET_TX_INT; > > bdp->cbd_bufaddr = cpu_to_fec32(dma_addr); > - bdp->cbd_datlen = cpu_to_fec16(frame->len); > + bdp->cbd_datlen = cpu_to_fec16(frame_len); > > if (fep->bufdesc_ex) { > struct bufdesc_ex *ebdp = (struct bufdesc_ex *)bdp; > @@ -3875,14 +3889,10 @@ static int fec_enet_xdp_tx_xmit(struct fec_enet_private *fep, > int cpu, struct xdp_buff *xdp, > u32 dma_sync_len) > { > - struct xdp_frame *xdpf = xdp_convert_buff_to_frame(xdp); > struct fec_enet_priv_tx_q *txq; > struct netdev_queue *nq; > int queue, ret; > > - if (unlikely(!xdpf)) > - return -EFAULT; > - > queue = fec_enet_xdp_get_tx_queue(fep, cpu); > txq = fep->tx_queue[queue]; > nq = netdev_get_tx_queue(fep->netdev, queue); > @@ -3891,7 +3901,7 @@ static int fec_enet_xdp_tx_xmit(struct fec_enet_private *fep, > > /* Avoid tx timeout as XDP shares the queue with kernel stack */ > txq_trans_cond_update(nq); > - ret = fec_enet_txq_xmit_frame(fep, txq, xdpf, dma_sync_len, false); > + ret = fec_enet_txq_xmit_frame(fep, txq, xdp, dma_sync_len, false); > > __netif_tx_unlock(nq); >
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