From 4cce66cdd14aa5006a011505865d932adb49f600 Mon Sep 17 00:00:00 2001 From: Thadeu Lima de Souza Cascardo Date: Mon, 16 Jul 2012 07:01:53 +0000 Subject: [PATCH] mlx4_en: map entire pages to increase throughput In its receive path, mlx4_en driver maps each page chunk that it pushes to the hardware and unmaps it when pushing it up the stack. This limits throughput to about 3Gbps on a Power7 8-core machine. One solution is to map the entire allocated page at once. However, this requires that we keep track of every page fragment we give to a descriptor. We also need to work with the discipline that all fragments will be released (in the sense that it will not be reused by the driver anymore) in the order they are allocated to the driver. This requires that we don't reuse any fragments, every single one of them must be reallocated. We do that by releasing all the fragments that are processed and only after finished processing the descriptors, we start the refill. We also must somehow guarantee that we either refill all fragments in a descriptor or none at all, without resorting to giving up a page fragment that we would have already given. Otherwise, we would break the discipline of only releasing the fragments in the order they were allocated. This has passed page allocation fault injections (restricted to the driver by using required-start and required-end) and device hotplug while 16 TCP streams were able to deliver more than 9Gbps. Signed-off-by: Thadeu Lima de Souza Cascardo Signed-off-by: David S. Miller --- drivers/net/ethernet/mellanox/mlx4/en_rx.c | 237 ++++++++++--------- drivers/net/ethernet/mellanox/mlx4/mlx4_en.h | 3 +- 2 files changed, 131 insertions(+), 109 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c index 796cd58e6229..f32e70300770 100644 --- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c +++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c @@ -41,41 +41,75 @@ #include "mlx4_en.h" - -static int mlx4_en_alloc_frag(struct mlx4_en_priv *priv, - struct mlx4_en_rx_desc *rx_desc, - struct page_frag *skb_frags, - struct mlx4_en_rx_alloc *ring_alloc, - int i) +static int mlx4_en_alloc_frags(struct mlx4_en_priv *priv, + struct mlx4_en_rx_desc *rx_desc, + struct mlx4_en_rx_alloc *frags, + struct mlx4_en_rx_alloc *ring_alloc) { - struct mlx4_en_frag_info *frag_info = &priv->frag_info[i]; - struct mlx4_en_rx_alloc *page_alloc = &ring_alloc[i]; + struct mlx4_en_rx_alloc page_alloc[MLX4_EN_MAX_RX_FRAGS]; + struct mlx4_en_frag_info *frag_info; struct page *page; dma_addr_t dma; + int i; - if (page_alloc->offset == frag_info->last_offset) { - /* Allocate new page */ - page = alloc_pages(GFP_ATOMIC | __GFP_COMP, MLX4_EN_ALLOC_ORDER); - if (!page) - return -ENOMEM; - - skb_frags[i].page = page_alloc->page; - skb_frags[i].offset = page_alloc->offset; - page_alloc->page = page; - page_alloc->offset = frag_info->frag_align; - } else { - page = page_alloc->page; - get_page(page); + for (i = 0; i < priv->num_frags; i++) { + frag_info = &priv->frag_info[i]; + if (ring_alloc[i].offset == frag_info->last_offset) { + page = alloc_pages(GFP_ATOMIC | __GFP_COMP, + MLX4_EN_ALLOC_ORDER); + if (!page) + goto out; + dma = dma_map_page(priv->ddev, page, 0, + MLX4_EN_ALLOC_SIZE, PCI_DMA_FROMDEVICE); + if (dma_mapping_error(priv->ddev, dma)) { + put_page(page); + goto out; + } + page_alloc[i].page = page; + page_alloc[i].dma = dma; + page_alloc[i].offset = frag_info->frag_align; + } else { + page_alloc[i].page = ring_alloc[i].page; + get_page(ring_alloc[i].page); + page_alloc[i].dma = ring_alloc[i].dma; + page_alloc[i].offset = ring_alloc[i].offset + + frag_info->frag_stride; + } + } - skb_frags[i].page = page; - skb_frags[i].offset = page_alloc->offset; - page_alloc->offset += frag_info->frag_stride; + for (i = 0; i < priv->num_frags; i++) { + frags[i] = ring_alloc[i]; + dma = ring_alloc[i].dma + ring_alloc[i].offset; + ring_alloc[i] = page_alloc[i]; + rx_desc->data[i].addr = cpu_to_be64(dma); } - dma = dma_map_single(priv->ddev, page_address(skb_frags[i].page) + - skb_frags[i].offset, frag_info->frag_size, - PCI_DMA_FROMDEVICE); - rx_desc->data[i].addr = cpu_to_be64(dma); + return 0; + + +out: + while (i--) { + frag_info = &priv->frag_info[i]; + if (ring_alloc[i].offset == frag_info->last_offset) + dma_unmap_page(priv->ddev, page_alloc[i].dma, + MLX4_EN_ALLOC_SIZE, PCI_DMA_FROMDEVICE); + put_page(page_alloc[i].page); + } + return -ENOMEM; +} + +static void mlx4_en_free_frag(struct mlx4_en_priv *priv, + struct mlx4_en_rx_alloc *frags, + int i) +{ + struct mlx4_en_frag_info *frag_info = &priv->frag_info[i]; + + if (frags[i].offset == frag_info->last_offset) { + dma_unmap_page(priv->ddev, frags[i].dma, MLX4_EN_ALLOC_SIZE, + PCI_DMA_FROMDEVICE); + } + if (frags[i].page) + put_page(frags[i].page); } static int mlx4_en_init_allocator(struct mlx4_en_priv *priv, @@ -91,6 +125,13 @@ static int mlx4_en_init_allocator(struct mlx4_en_priv *priv, if (!page_alloc->page) goto out; + page_alloc->dma = dma_map_page(priv->ddev, page_alloc->page, 0, + MLX4_EN_ALLOC_SIZE, PCI_DMA_FROMDEVICE); + if (dma_mapping_error(priv->ddev, page_alloc->dma)) { + put_page(page_alloc->page); + page_alloc->page = NULL; + goto out; + } page_alloc->offset = priv->frag_info[i].frag_align; en_dbg(DRV, priv, "Initialized allocator:%d with page:%p\n", i, page_alloc->page); @@ -100,6 +141,8 @@ static int mlx4_en_init_allocator(struct mlx4_en_priv *priv, out: while (i--) { page_alloc = &ring->page_alloc[i]; + dma_unmap_page(priv->ddev, page_alloc->dma, + MLX4_EN_ALLOC_SIZE, PCI_DMA_FROMDEVICE); put_page(page_alloc->page); page_alloc->page = NULL; } @@ -117,24 +160,22 @@ static void mlx4_en_destroy_allocator(struct mlx4_en_priv *priv, en_dbg(DRV, priv, "Freeing allocator:%d count:%d\n", i, page_count(page_alloc->page)); + dma_unmap_page(priv->ddev, page_alloc->dma, + MLX4_EN_ALLOC_SIZE, PCI_DMA_FROMDEVICE); put_page(page_alloc->page); page_alloc->page = NULL; } } - static void mlx4_en_init_rx_desc(struct mlx4_en_priv *priv, struct mlx4_en_rx_ring *ring, int index) { struct mlx4_en_rx_desc *rx_desc = ring->buf + ring->stride * index; - struct skb_frag_struct *skb_frags = ring->rx_info + - (index << priv->log_rx_info); int possible_frags; int i; /* Set size and memtype fields */ for (i = 0; i < priv->num_frags; i++) { - skb_frag_size_set(&skb_frags[i], priv->frag_info[i].frag_size); rx_desc->data[i].byte_count = cpu_to_be32(priv->frag_info[i].frag_size); rx_desc->data[i].lkey = cpu_to_be32(priv->mdev->mr.key); @@ -151,29 +192,14 @@ static void mlx4_en_init_rx_desc(struct mlx4_en_priv *priv, } } - static int mlx4_en_prepare_rx_desc(struct mlx4_en_priv *priv, struct mlx4_en_rx_ring *ring, int index) { struct mlx4_en_rx_desc *rx_desc = ring->buf + (index * ring->stride); - struct page_frag *skb_frags = ring->rx_info + - (index << priv->log_rx_info); - int i; + struct mlx4_en_rx_alloc *frags = ring->rx_info + + (index << priv->log_rx_info); - for (i = 0; i < priv->num_frags; i++) - if (mlx4_en_alloc_frag(priv, rx_desc, skb_frags, ring->page_alloc, i)) - goto err; - - return 0; - -err: - while (i--) { - dma_addr_t dma = be64_to_cpu(rx_desc->data[i].addr); - pci_unmap_single(priv->mdev->pdev, dma, skb_frags[i].size, - PCI_DMA_FROMDEVICE); - put_page(skb_frags[i].page); - } - return -ENOMEM; + return mlx4_en_alloc_frags(priv, rx_desc, frags, ring->page_alloc); } static inline void mlx4_en_update_rx_prod_db(struct mlx4_en_rx_ring *ring) @@ -185,20 +211,13 @@ static void mlx4_en_free_rx_desc(struct mlx4_en_priv *priv, struct mlx4_en_rx_ring *ring, int index) { - struct page_frag *skb_frags; - struct mlx4_en_rx_desc *rx_desc = ring->buf + (index << ring->log_stride); - dma_addr_t dma; + struct mlx4_en_rx_alloc *frags; int nr; - skb_frags = ring->rx_info + (index << priv->log_rx_info); + frags = ring->rx_info + (index << priv->log_rx_info); for (nr = 0; nr < priv->num_frags; nr++) { en_dbg(DRV, priv, "Freeing fragment:%d\n", nr); - dma = be64_to_cpu(rx_desc->data[nr].addr); - - en_dbg(DRV, priv, "Unmapping buffer at dma:0x%llx\n", (u64) dma); - dma_unmap_single(priv->ddev, dma, skb_frags[nr].size, - PCI_DMA_FROMDEVICE); - put_page(skb_frags[nr].page); + mlx4_en_free_frag(priv, frags, nr); } } @@ -268,10 +287,9 @@ int mlx4_en_create_rx_ring(struct mlx4_en_priv *priv, struct mlx4_en_rx_ring *ring, u32 size, u16 stride) { struct mlx4_en_dev *mdev = priv->mdev; - int err; + int err = -ENOMEM; int tmp; - ring->prod = 0; ring->cons = 0; ring->size = size; @@ -281,7 +299,7 @@ int mlx4_en_create_rx_ring(struct mlx4_en_priv *priv, ring->buf_size = ring->size * ring->stride + TXBB_SIZE; tmp = size * roundup_pow_of_two(MLX4_EN_MAX_RX_FRAGS * - sizeof(struct skb_frag_struct)); + sizeof(struct mlx4_en_rx_alloc)); ring->rx_info = vmalloc(tmp); if (!ring->rx_info) return -ENOMEM; @@ -338,7 +356,7 @@ int mlx4_en_activate_rx_rings(struct mlx4_en_priv *priv) memset(ring->buf, 0, ring->buf_size); mlx4_en_update_rx_prod_db(ring); - /* Initailize all descriptors */ + /* Initialize all descriptors */ for (i = 0; i < ring->size; i++) mlx4_en_init_rx_desc(priv, ring, i); @@ -404,12 +422,10 @@ void mlx4_en_deactivate_rx_ring(struct mlx4_en_priv *priv, } -/* Unmap a completed descriptor and free unused pages */ static int mlx4_en_complete_rx_desc(struct mlx4_en_priv *priv, struct mlx4_en_rx_desc *rx_desc, - struct page_frag *skb_frags, + struct mlx4_en_rx_alloc *frags, struct sk_buff *skb, - struct mlx4_en_rx_alloc *page_alloc, int length) { struct skb_frag_struct *skb_frags_rx = skb_shinfo(skb)->frags; @@ -417,26 +433,24 @@ static int mlx4_en_complete_rx_desc(struct mlx4_en_priv *priv, int nr; dma_addr_t dma; - /* Collect used fragments while replacing them in the HW descirptors */ + /* Collect used fragments while replacing them in the HW descriptors */ for (nr = 0; nr < priv->num_frags; nr++) { frag_info = &priv->frag_info[nr]; if (length <= frag_info->frag_prefix_size) break; + if (!frags[nr].page) + goto fail; - /* Save page reference in skb */ - __skb_frag_set_page(&skb_frags_rx[nr], skb_frags[nr].page); - skb_frag_size_set(&skb_frags_rx[nr], skb_frags[nr].size); - skb_frags_rx[nr].page_offset = skb_frags[nr].offset; - skb->truesize += frag_info->frag_stride; dma = be64_to_cpu(rx_desc->data[nr].addr); + dma_sync_single_for_cpu(priv->ddev, dma, frag_info->frag_size, + DMA_FROM_DEVICE); - /* Allocate a replacement page */ - if (mlx4_en_alloc_frag(priv, rx_desc, skb_frags, page_alloc, nr)) - goto fail; - - /* Unmap buffer */ - dma_unmap_single(priv->ddev, dma, skb_frag_size(&skb_frags_rx[nr]), - PCI_DMA_FROMDEVICE); + /* Save page reference in skb */ + get_page(frags[nr].page); + __skb_frag_set_page(&skb_frags_rx[nr], frags[nr].page); + skb_frag_size_set(&skb_frags_rx[nr], frag_info->frag_size); + skb_frags_rx[nr].page_offset = frags[nr].offset; + skb->truesize += frag_info->frag_stride; } /* Adjust size of last fragment to match actual length */ if (nr > 0) @@ -445,8 +459,6 @@ static int mlx4_en_complete_rx_desc(struct mlx4_en_priv *priv, return nr; fail: - /* Drop all accumulated fragments (which have already been replaced in - * the descriptor) of this packet; remaining fragments are reused... */ while (nr > 0) { nr--; __skb_frag_unref(&skb_frags_rx[nr]); @@ -457,8 +469,7 @@ static int mlx4_en_complete_rx_desc(struct mlx4_en_priv *priv, static struct sk_buff *mlx4_en_rx_skb(struct mlx4_en_priv *priv, struct mlx4_en_rx_desc *rx_desc, - struct page_frag *skb_frags, - struct mlx4_en_rx_alloc *page_alloc, + struct mlx4_en_rx_alloc *frags, unsigned int length) { struct sk_buff *skb; @@ -476,23 +487,20 @@ static struct sk_buff *mlx4_en_rx_skb(struct mlx4_en_priv *priv, /* Get pointer to first fragment so we could copy the headers into the * (linear part of the) skb */ - va = page_address(skb_frags[0].page) + skb_frags[0].offset; + va = page_address(frags[0].page) + frags[0].offset; if (length <= SMALL_PACKET_SIZE) { /* We are copying all relevant data to the skb - temporarily - * synch buffers for the copy */ + * sync buffers for the copy */ dma = be64_to_cpu(rx_desc->data[0].addr); dma_sync_single_for_cpu(priv->ddev, dma, length, DMA_FROM_DEVICE); skb_copy_to_linear_data(skb, va, length); - dma_sync_single_for_device(priv->ddev, dma, length, - DMA_FROM_DEVICE); skb->tail += length; } else { - /* Move relevant fragments to skb */ - used_frags = mlx4_en_complete_rx_desc(priv, rx_desc, skb_frags, - skb, page_alloc, length); + used_frags = mlx4_en_complete_rx_desc(priv, rx_desc, frags, + skb, length); if (unlikely(!used_frags)) { kfree_skb(skb); return NULL; @@ -529,12 +537,25 @@ static void validate_loopback(struct mlx4_en_priv *priv, struct sk_buff *skb) dev_kfree_skb_any(skb); } +static void mlx4_en_refill_rx_buffers(struct mlx4_en_priv *priv, + struct mlx4_en_rx_ring *ring) +{ + int index = ring->prod & ring->size_mask; + + while ((u32) (ring->prod - ring->cons) < ring->actual_size) { + if (mlx4_en_prepare_rx_desc(priv, ring, index)) + break; + ring->prod++; + index = ring->prod & ring->size_mask; + } +} + int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int budget) { struct mlx4_en_priv *priv = netdev_priv(dev); struct mlx4_cqe *cqe; struct mlx4_en_rx_ring *ring = &priv->rx_ring[cq->ring]; - struct page_frag *skb_frags; + struct mlx4_en_rx_alloc *frags; struct mlx4_en_rx_desc *rx_desc; struct sk_buff *skb; int index; @@ -543,6 +564,7 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud int polled = 0; int ip_summed; struct ethhdr *ethh; + dma_addr_t dma; u64 s_mac; if (!priv->port_up) @@ -558,7 +580,7 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud while (XNOR(cqe->owner_sr_opcode & MLX4_CQE_OWNER_MASK, cq->mcq.cons_index & cq->size)) { - skb_frags = ring->rx_info + (index << priv->log_rx_info); + frags = ring->rx_info + (index << priv->log_rx_info); rx_desc = ring->buf + (index << ring->log_stride); /* @@ -582,8 +604,11 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud /* Get pointer to first fragment since we haven't skb yet and * cast it to ethhdr struct */ - ethh = (struct ethhdr *)(page_address(skb_frags[0].page) + - skb_frags[0].offset); + dma = be64_to_cpu(rx_desc->data[0].addr); + dma_sync_single_for_cpu(priv->ddev, dma, sizeof(*ethh), + DMA_FROM_DEVICE); + ethh = (struct ethhdr *)(page_address(frags[0].page) + + frags[0].offset); s_mac = mlx4_en_mac_to_u64(ethh->h_source); /* If source MAC is equal to our own MAC and not performing @@ -615,10 +640,9 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud if (!gro_skb) goto next; - nr = mlx4_en_complete_rx_desc( - priv, rx_desc, - skb_frags, gro_skb, - ring->page_alloc, length); + nr = mlx4_en_complete_rx_desc(priv, + rx_desc, frags, gro_skb, + length); if (!nr) goto next; @@ -654,8 +678,7 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud ring->csum_none++; } - skb = mlx4_en_rx_skb(priv, rx_desc, skb_frags, - ring->page_alloc, length); + skb = mlx4_en_rx_skb(priv, rx_desc, frags, length); if (!skb) { priv->stats.rx_dropped++; goto next; @@ -681,6 +704,9 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud netif_receive_skb(skb); next: + for (nr = 0; nr < priv->num_frags; nr++) + mlx4_en_free_frag(priv, frags, nr); + ++cq->mcq.cons_index; index = (cq->mcq.cons_index) & ring->size_mask; cqe = &cq->buf[index]; @@ -696,7 +722,7 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud mlx4_cq_set_ci(&cq->mcq); wmb(); /* ensure HW sees CQ consumer before we post new buffers */ ring->cons = cq->mcq.cons_index; - ring->prod += polled; /* Polled descriptors were realocated in place */ + mlx4_en_refill_rx_buffers(priv, ring); mlx4_en_update_rx_prod_db(ring); return polled; } @@ -785,7 +811,7 @@ void mlx4_en_calc_rx_buf(struct net_device *dev) priv->num_frags = i; priv->rx_skb_size = eff_mtu; - priv->log_rx_info = ROUNDUP_LOG2(i * sizeof(struct skb_frag_struct)); + priv->log_rx_info = ROUNDUP_LOG2(i * sizeof(struct mlx4_en_rx_alloc)); en_dbg(DRV, priv, "Rx buffer scatter-list (effective-mtu:%d " "num_frags:%d):\n", eff_mtu, priv->num_frags); @@ -987,8 +1013,3 @@ void mlx4_en_release_rss_steer(struct mlx4_en_priv *priv) } mlx4_qp_release_range(mdev->dev, rss_map->base_qpn, priv->rx_ring_num); } - - - - - diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h index af34c98d43e5..5f1ab105debc 100644 --- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h +++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h @@ -111,7 +111,7 @@ enum { #define MLX4_EN_MAX_TX_SIZE 8192 #define MLX4_EN_MAX_RX_SIZE 8192 -/* Minimum ring size for our page-allocation sceme to work */ +/* Minimum ring size for our page-allocation scheme to work */ #define MLX4_EN_MIN_RX_SIZE (MLX4_EN_ALLOC_SIZE / SMP_CACHE_BYTES) #define MLX4_EN_MIN_TX_SIZE (4096 / TXBB_SIZE) @@ -232,6 +232,7 @@ struct mlx4_en_tx_desc { struct mlx4_en_rx_alloc { struct page *page; + dma_addr_t dma; u16 offset; }; -- GitLab