On Wed, 16 Oct 2019 23:03:08 +0200, Lorenzo Bianconi wrote: > Refactor mvneta_rx_swbm code introducing mvneta_swbm_rx_frame and > mvneta_swbm_add_rx_fragment routines. Rely on build_skb in oreder to > allocate skb since the previous patch introduced buffer recycling using > the page_pool API. > This patch fixes even an issue in the original driver where dma buffers > are accessed before dma sync. > mvneta driver can run on not cache coherent devices so it is > necessary to sync DMA buffers before sending them to the device > in order to avoid memory corruptions. Running perf analysis we can > see a performance cost associated with this DMA-sync (anyway it is > already there in the original driver code). In follow up patches we > will add more logic to reduce DMA-sync as much as possible. > > Signed-off-by: Ilias Apalodimas <ilias.apalodi...@linaro.org> > Signed-off-by: Jesper Dangaard Brouer <bro...@redhat.com> > Signed-off-by: Lorenzo Bianconi <lore...@kernel.org> > --- > drivers/net/ethernet/marvell/mvneta.c | 201 ++++++++++++++------------ > 1 file changed, 107 insertions(+), 94 deletions(-) > > diff --git a/drivers/net/ethernet/marvell/mvneta.c > b/drivers/net/ethernet/marvell/mvneta.c > index 9e4d828787fd..2f8123224f6e 100644 > --- a/drivers/net/ethernet/marvell/mvneta.c > +++ b/drivers/net/ethernet/marvell/mvneta.c > @@ -323,6 +323,11 @@ > ETH_HLEN + ETH_FCS_LEN, \ > cache_line_size()) > > +#define MVNETA_SKB_PAD (SKB_DATA_ALIGN(sizeof(struct skb_shared_info) > + \ > + NET_SKB_PAD)) > +#define MVNETA_SKB_SIZE(len) (SKB_DATA_ALIGN(len) + MVNETA_SKB_PAD) > +#define MVNETA_MAX_RX_BUF_SIZE (PAGE_SIZE - MVNETA_SKB_PAD) > + > #define IS_TSO_HEADER(txq, addr) \ > ((addr >= txq->tso_hdrs_phys) && \ > (addr < txq->tso_hdrs_phys + txq->size * TSO_HEADER_SIZE)) > @@ -646,7 +651,6 @@ static int txq_number = 8; > static int rxq_def; > > static int rx_copybreak __read_mostly = 256; > -static int rx_header_size __read_mostly = 128; > > /* HW BM need that each port be identify by a unique ID */ > static int global_port_id; > @@ -1817,6 +1821,7 @@ static int mvneta_rx_refill(struct mvneta_port *pp, > struct mvneta_rx_queue *rxq, > gfp_t gfp_mask) > { > + enum dma_data_direction dma_dir; > dma_addr_t phys_addr; > struct page *page; > > @@ -1826,6 +1831,9 @@ static int mvneta_rx_refill(struct mvneta_port *pp, > return -ENOMEM; > > phys_addr = page_pool_get_dma_addr(page) + pp->rx_offset_correction; > + dma_dir = page_pool_get_dma_dir(rxq->page_pool); > + dma_sync_single_for_device(pp->dev->dev.parent, phys_addr, > + MVNETA_MAX_RX_BUF_SIZE, dma_dir);
This belongs in patch 2. > mvneta_rx_desc_fill(rx_desc, phys_addr, page, rxq); > > return 0; > @@ -1942,30 +1950,101 @@ int mvneta_rx_refill_queue(struct mvneta_port *pp, > struct mvneta_rx_queue *rxq) > return i; > } > /* Main rx processing when using software buffer management */ > static int mvneta_rx_swbm(struct napi_struct *napi, > struct mvneta_port *pp, int budget, > struct mvneta_rx_queue *rxq) > { > - struct net_device *dev = pp->dev; > - int rx_todo, rx_proc; > - int refill = 0; > - u32 rcvd_pkts = 0; > - u32 rcvd_bytes = 0; > + int rcvd_pkts = 0, rcvd_bytes = 0; > + int rx_pending, refill, done = 0; > > /* Get number of received packets */ > - rx_todo = mvneta_rxq_busy_desc_num_get(pp, rxq); > - rx_proc = 0; > + rx_pending = mvneta_rxq_busy_desc_num_get(pp, rxq); > > /* Fairness NAPI loop */ > - while ((rcvd_pkts < budget) && (rx_proc < rx_todo)) { > + while (done < budget && done < rx_pending) { > struct mvneta_rx_desc *rx_desc = mvneta_rxq_next_desc_get(rxq); > unsigned char *data; > struct page *page; > - dma_addr_t phys_addr; > - u32 rx_status, index; > - int rx_bytes, skb_size, copy_size; > - int frag_num, frag_size, frag_offset; > + int index; > > index = rx_desc - rxq->descs; > page = (struct page *)rxq->buf_virt_addr[index]; > @@ -1973,98 +2052,33 @@ static int mvneta_rx_swbm(struct napi_struct *napi, > /* Prefetch header */ > prefetch(data); > > - phys_addr = rx_desc->buf_phys_addr; > - rx_status = rx_desc->status; > - rx_proc++; > rxq->refill_num++; > + done++; > + > + if (rx_desc->status & MVNETA_RXD_FIRST_DESC) { > + int err; > > - if (rx_status & MVNETA_RXD_FIRST_DESC) { If I may nit pick - not removing the rx_status and dev local variables could make this chunk a little bit more readable - could you experiment in moving that to a separate patch? > /* Check errors only for FIRST descriptor */ > - if (rx_status & MVNETA_RXD_ERR_SUMMARY) { > + if (rx_desc->status & MVNETA_RXD_ERR_SUMMARY) { > mvneta_rx_error(pp, rx_desc); > - dev->stats.rx_errors++; > + pp->dev->stats.rx_errors++; > /* leave the descriptor untouched */ > continue; > } > - rx_bytes = rx_desc->data_size - > - (ETH_FCS_LEN + MVNETA_MH_SIZE); > > - /* Allocate small skb for each new packet */ > - skb_size = max(rx_copybreak, rx_header_size); > - rxq->skb = netdev_alloc_skb_ip_align(dev, skb_size); > - if (unlikely(!rxq->skb)) { > - netdev_err(dev, > - "Can't allocate skb on queue %d\n", > - rxq->id); > - dev->stats.rx_dropped++; > - rxq->skb_alloc_err++; > + err = mvneta_swbm_rx_frame(pp, rx_desc, rxq, page); > + if (err) > continue; > - } > - copy_size = min(skb_size, rx_bytes); > - > - /* Copy data from buffer to SKB, skip Marvell header */ > - memcpy(rxq->skb->data, data + MVNETA_MH_SIZE, > - copy_size); > - skb_put(rxq->skb, copy_size); > - rxq->left_size = rx_bytes - copy_size; > - > - mvneta_rx_csum(pp, rx_status, rxq->skb); > - if (rxq->left_size == 0) { > - int size = copy_size + MVNETA_MH_SIZE; > - > - dma_sync_single_range_for_cpu(dev->dev.parent, > - phys_addr, 0, > - size, > - DMA_FROM_DEVICE); > - > - /* leave the descriptor and buffer untouched */ > - } else { > - /* refill descriptor with new buffer later */ > - rx_desc->buf_phys_addr = 0; > - > - frag_num = 0; > - frag_offset = copy_size + MVNETA_MH_SIZE; > - frag_size = min(rxq->left_size, > - (int)(PAGE_SIZE - frag_offset)); > - skb_add_rx_frag(rxq->skb, frag_num, page, > - frag_offset, frag_size, > - PAGE_SIZE); > - page_pool_release_page(rxq->page_pool, page); > - rxq->left_size -= frag_size; > - } > } else { > - /* Middle or Last descriptor */ > if (unlikely(!rxq->skb)) { > pr_debug("no skb for rx_status 0x%x\n", > - rx_status); > + rx_desc->status); > continue; > } > - if (!rxq->left_size) { > - /* last descriptor has only FCS */ > - /* and can be discarded */ > - dma_sync_single_range_for_cpu(dev->dev.parent, > - phys_addr, 0, > - ETH_FCS_LEN, > - DMA_FROM_DEVICE); > - /* leave the descriptor and buffer untouched */ > - } else { > - /* refill descriptor with new buffer later */ > - rx_desc->buf_phys_addr = 0; > - > - frag_num = skb_shinfo(rxq->skb)->nr_frags; > - frag_offset = 0; > - frag_size = min(rxq->left_size, > - (int)(PAGE_SIZE - frag_offset)); > - skb_add_rx_frag(rxq->skb, frag_num, page, > - frag_offset, frag_size, > - PAGE_SIZE); > - > - page_pool_release_page(rxq->page_pool, page); > - rxq->left_size -= frag_size; > - } > + mvneta_swbm_add_rx_fragment(pp, rx_desc, rxq, page); > } /* Middle or Last descriptor */ > > - if (!(rx_status & MVNETA_RXD_LAST_DESC)) > + if (!(rx_desc->status & MVNETA_RXD_LAST_DESC)) > /* no last descriptor this time */ > continue; > > @@ -2080,13 +2094,12 @@ static int mvneta_rx_swbm(struct napi_struct *napi, > rcvd_bytes += rxq->skb->len; > > /* Linux processing */ > - rxq->skb->protocol = eth_type_trans(rxq->skb, dev); > + rxq->skb->protocol = eth_type_trans(rxq->skb, pp->dev); > > napi_gro_receive(napi, rxq->skb); > > /* clean uncomplete skb pointer in queue */ > rxq->skb = NULL; > - rxq->left_size = 0; > } > > mvneta_update_stats(pp, rcvd_pkts, rcvd_bytes, false);