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SubjectRE: [PATCH net-next 3/3] net: stmmac: Introducing support for Page Pool
Date
++ Jesper: Who is most active committer of page pool API (?) ... Can you 
please help review this ?

From: Jose Abreu <joabreu@synopsys.com>

> Mapping and unmapping DMA region is an high bottleneck in stmmac driver,
> specially in the RX path.
>
> This commit introduces support for Page Pool API and uses it in all RX
> queues. With this change, we get more stable troughput and some increase
> of banwidth with iperf:
> - MAC1000 - 950 Mbps
> - XGMAC: 9.22 Gbps
>
> Signed-off-by: Jose Abreu <joabreu@synopsys.com>
> Cc: Joao Pinto <jpinto@synopsys.com>
> Cc: David S. Miller <davem@davemloft.net>
> Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com>
> Cc: Alexandre Torgue <alexandre.torgue@st.com>
> Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
> Cc: Maxime Ripard <maxime.ripard@bootlin.com>
> Cc: Chen-Yu Tsai <wens@csie.org>
> ---
> drivers/net/ethernet/stmicro/stmmac/Kconfig | 1 +
> drivers/net/ethernet/stmicro/stmmac/stmmac.h | 10 +-
> drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 196 ++++++----------------
> 3 files changed, 63 insertions(+), 144 deletions(-)
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/Kconfig b/drivers/net/ethernet/stmicro/stmmac/Kconfig
> index 943189dcccb1..2325b40dff6e 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/Kconfig
> +++ b/drivers/net/ethernet/stmicro/stmmac/Kconfig
> @@ -3,6 +3,7 @@ config STMMAC_ETH
> tristate "STMicroelectronics Multi-Gigabit Ethernet driver"
> depends on HAS_IOMEM && HAS_DMA
> select MII
> + select PAGE_POOL
> select PHYLINK
> select CRC32
> imply PTP_1588_CLOCK
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
> index 513f4e2df5f6..5cd966c154f3 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
> @@ -20,6 +20,7 @@
> #include <linux/ptp_clock_kernel.h>
> #include <linux/net_tstamp.h>
> #include <linux/reset.h>
> +#include <net/page_pool.h>
>
> struct stmmac_resources {
> void __iomem *addr;
> @@ -54,14 +55,19 @@ struct stmmac_tx_queue {
> u32 mss;
> };
>
> +struct stmmac_rx_buffer {
> + struct page *page;
> + dma_addr_t addr;
> +};
> +
> struct stmmac_rx_queue {
> u32 rx_count_frames;
> u32 queue_index;
> + struct page_pool *page_pool;
> + struct stmmac_rx_buffer *buf_pool;
> struct stmmac_priv *priv_data;
> struct dma_extended_desc *dma_erx;
> struct dma_desc *dma_rx ____cacheline_aligned_in_smp;
> - struct sk_buff **rx_skbuff;
> - dma_addr_t *rx_skbuff_dma;
> unsigned int cur_rx;
> unsigned int dirty_rx;
> u32 rx_zeroc_thresh;
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index c8fe85ef9a7e..9f44e8193208 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -1197,26 +1197,14 @@ static int stmmac_init_rx_buffers(struct stmmac_priv *priv, struct dma_desc *p,
> int i, gfp_t flags, u32 queue)
> {
> struct stmmac_rx_queue *rx_q = &priv->rx_queue[queue];
> - struct sk_buff *skb;
> + struct stmmac_rx_buffer *buf = &rx_q->buf_pool[i];
>
> - skb = __netdev_alloc_skb_ip_align(priv->dev, priv->dma_buf_sz, flags);
> - if (!skb) {
> - netdev_err(priv->dev,
> - "%s: Rx init fails; skb is NULL\n", __func__);
> + buf->page = page_pool_dev_alloc_pages(rx_q->page_pool);
> + if (!buf->page)
> return -ENOMEM;
> - }
> - rx_q->rx_skbuff[i] = skb;
> - rx_q->rx_skbuff_dma[i] = dma_map_single(priv->device, skb->data,
> - priv->dma_buf_sz,
> - DMA_FROM_DEVICE);
> - if (dma_mapping_error(priv->device, rx_q->rx_skbuff_dma[i])) {
> - netdev_err(priv->dev, "%s: DMA mapping error\n", __func__);
> - dev_kfree_skb_any(skb);
> - return -EINVAL;
> - }
> -
> - stmmac_set_desc_addr(priv, p, rx_q->rx_skbuff_dma[i]);
>
> + buf->addr = buf->page->dma_addr;
> + stmmac_set_desc_addr(priv, p, buf->addr);
> if (priv->dma_buf_sz == BUF_SIZE_16KiB)
> stmmac_init_desc3(priv, p);
>
> @@ -1232,13 +1220,10 @@ static int stmmac_init_rx_buffers(struct stmmac_priv *priv, struct dma_desc *p,
> static void stmmac_free_rx_buffer(struct stmmac_priv *priv, u32 queue, int i)
> {
> struct stmmac_rx_queue *rx_q = &priv->rx_queue[queue];
> + struct stmmac_rx_buffer *buf = &rx_q->buf_pool[i];
>
> - if (rx_q->rx_skbuff[i]) {
> - dma_unmap_single(priv->device, rx_q->rx_skbuff_dma[i],
> - priv->dma_buf_sz, DMA_FROM_DEVICE);
> - dev_kfree_skb_any(rx_q->rx_skbuff[i]);
> - }
> - rx_q->rx_skbuff[i] = NULL;
> + page_pool_put_page(rx_q->page_pool, buf->page, false);
> + buf->page = NULL;
> }
>
> /**
> @@ -1321,10 +1306,6 @@ static int init_dma_rx_desc_rings(struct net_device *dev, gfp_t flags)
> queue);
> if (ret)
> goto err_init_rx_buffers;
> -
> - netif_dbg(priv, probe, priv->dev, "[%p]\t[%p]\t[%x]\n",
> - rx_q->rx_skbuff[i], rx_q->rx_skbuff[i]->data,
> - (unsigned int)rx_q->rx_skbuff_dma[i]);
> }
>
> rx_q->cur_rx = 0;
> @@ -1498,8 +1479,9 @@ static void free_dma_rx_desc_resources(struct stmmac_priv *priv)
> sizeof(struct dma_extended_desc),
> rx_q->dma_erx, rx_q->dma_rx_phy);
>
> - kfree(rx_q->rx_skbuff_dma);
> - kfree(rx_q->rx_skbuff);
> + kfree(rx_q->buf_pool);
> + if (rx_q->page_pool)
> + page_pool_request_shutdown(rx_q->page_pool);
> }
> }
>
> @@ -1551,20 +1533,28 @@ static int alloc_dma_rx_desc_resources(struct stmmac_priv *priv)
> /* RX queues buffers and DMA */
> for (queue = 0; queue < rx_count; queue++) {
> struct stmmac_rx_queue *rx_q = &priv->rx_queue[queue];
> + struct page_pool_params pp_params = { 0 };
>
> rx_q->queue_index = queue;
> rx_q->priv_data = priv;
>
> - rx_q->rx_skbuff_dma = kmalloc_array(DMA_RX_SIZE,
> - sizeof(dma_addr_t),
> - GFP_KERNEL);
> - if (!rx_q->rx_skbuff_dma)
> + pp_params.flags = PP_FLAG_DMA_MAP;
> + pp_params.order = DIV_ROUND_UP(priv->dma_buf_sz, PAGE_SIZE);
> + pp_params.nid = dev_to_node(priv->device);
> + pp_params.dev = priv->device;
> + pp_params.dma_dir = DMA_FROM_DEVICE;
> +
> + rx_q->page_pool = page_pool_create(&pp_params);
> + if (IS_ERR(rx_q->page_pool)) {
> + ret = PTR_ERR(rx_q->page_pool);
> + rx_q->page_pool = NULL;
> goto err_dma;
> + }
>
> - rx_q->rx_skbuff = kmalloc_array(DMA_RX_SIZE,
> - sizeof(struct sk_buff *),
> - GFP_KERNEL);
> - if (!rx_q->rx_skbuff)
> + rx_q->buf_pool = kmalloc_array(DMA_RX_SIZE,
> + sizeof(*rx_q->buf_pool),
> + GFP_KERNEL);
> + if (!rx_q->buf_pool)
> goto err_dma;
>
> if (priv->extend_desc) {
> @@ -3295,9 +3285,8 @@ static inline void stmmac_rx_refill(struct stmmac_priv *priv, u32 queue)
> int dirty = stmmac_rx_dirty(priv, queue);
> unsigned int entry = rx_q->dirty_rx;
>
> - int bfsize = priv->dma_buf_sz;
> -
> while (dirty-- > 0) {
> + struct stmmac_rx_buffer *buf = &rx_q->buf_pool[entry];
> struct dma_desc *p;
> bool use_rx_wd;
>
> @@ -3306,49 +3295,22 @@ static inline void stmmac_rx_refill(struct stmmac_priv *priv, u32 queue)
> else
> p = rx_q->dma_rx + entry;
>
> - if (likely(!rx_q->rx_skbuff[entry])) {
> - struct sk_buff *skb;
> -
> - skb = netdev_alloc_skb_ip_align(priv->dev, bfsize);
> - if (unlikely(!skb)) {
> - /* so for a while no zero-copy! */
> - rx_q->rx_zeroc_thresh = STMMAC_RX_THRESH;
> - if (unlikely(net_ratelimit()))
> - dev_err(priv->device,
> - "fail to alloc skb entry %d\n",
> - entry);
> - break;
> - }
> -
> - rx_q->rx_skbuff[entry] = skb;
> - rx_q->rx_skbuff_dma[entry] =
> - dma_map_single(priv->device, skb->data, bfsize,
> - DMA_FROM_DEVICE);
> - if (dma_mapping_error(priv->device,
> - rx_q->rx_skbuff_dma[entry])) {
> - netdev_err(priv->dev, "Rx DMA map failed\n");
> - dev_kfree_skb(skb);
> + if (!buf->page) {
> + buf->page = page_pool_dev_alloc_pages(rx_q->page_pool);
> + if (!buf->page)
> break;
> - }
> -
> - stmmac_set_desc_addr(priv, p, rx_q->rx_skbuff_dma[entry]);
> - stmmac_refill_desc3(priv, rx_q, p);
> -
> - if (rx_q->rx_zeroc_thresh > 0)
> - rx_q->rx_zeroc_thresh--;
> -
> - netif_dbg(priv, rx_status, priv->dev,
> - "refill entry #%d\n", entry);
> }
> - dma_wmb();
> +
> + buf->addr = buf->page->dma_addr;
> + stmmac_set_desc_addr(priv, p, buf->addr);
> + stmmac_refill_desc3(priv, rx_q, p);
>
> rx_q->rx_count_frames++;
> rx_q->rx_count_frames %= priv->rx_coal_frames;
> use_rx_wd = priv->use_riwt && rx_q->rx_count_frames;
>
> - stmmac_set_rx_owner(priv, p, use_rx_wd);
> -
> dma_wmb();
> + stmmac_set_rx_owner(priv, p, use_rx_wd);
>
> entry = STMMAC_GET_ENTRY(entry, DMA_RX_SIZE);
> }
> @@ -3373,9 +3335,6 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
> unsigned int next_entry = rx_q->cur_rx;
> int coe = priv->hw->rx_csum;
> unsigned int count = 0;
> - bool xmac;
> -
> - xmac = priv->plat->has_gmac4 || priv->plat->has_xgmac;
>
> if (netif_msg_rx_status(priv)) {
> void *rx_head;
> @@ -3389,11 +3348,12 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
> stmmac_display_ring(priv, rx_head, DMA_RX_SIZE, true);
> }
> while (count < limit) {
> + struct stmmac_rx_buffer *buf;
> + struct dma_desc *np, *p;
> int entry, status;
> - struct dma_desc *p;
> - struct dma_desc *np;
>
> entry = next_entry;
> + buf = &rx_q->buf_pool[entry];
>
> if (priv->extend_desc)
> p = (struct dma_desc *)(rx_q->dma_erx + entry);
> @@ -3423,20 +3383,9 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
> stmmac_rx_extended_status(priv, &priv->dev->stats,
> &priv->xstats, rx_q->dma_erx + entry);
> if (unlikely(status == discard_frame)) {
> + page_pool_recycle_direct(rx_q->page_pool, buf->page);
> priv->dev->stats.rx_errors++;
> - if (priv->hwts_rx_en && !priv->extend_desc) {
> - /* DESC2 & DESC3 will be overwritten by device
> - * with timestamp value, hence reinitialize
> - * them in stmmac_rx_refill() function so that
> - * device can reuse it.
> - */
> - dev_kfree_skb_any(rx_q->rx_skbuff[entry]);
> - rx_q->rx_skbuff[entry] = NULL;
> - dma_unmap_single(priv->device,
> - rx_q->rx_skbuff_dma[entry],
> - priv->dma_buf_sz,
> - DMA_FROM_DEVICE);
> - }
> + buf->page = NULL;
> } else {
> struct sk_buff *skb;
> int frame_len;
> @@ -3476,58 +3425,18 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
> frame_len, status);
> }
>
> - /* The zero-copy is always used for all the sizes
> - * in case of GMAC4 because it needs
> - * to refill the used descriptors, always.
> - */
> - if (unlikely(!xmac &&
> - ((frame_len < priv->rx_copybreak) ||
> - stmmac_rx_threshold_count(rx_q)))) {
> - skb = netdev_alloc_skb_ip_align(priv->dev,
> - frame_len);
> - if (unlikely(!skb)) {
> - if (net_ratelimit())
> - dev_warn(priv->device,
> - "packet dropped\n");
> - priv->dev->stats.rx_dropped++;
> - continue;
> - }
> -
> - dma_sync_single_for_cpu(priv->device,
> - rx_q->rx_skbuff_dma
> - [entry], frame_len,
> - DMA_FROM_DEVICE);
> - skb_copy_to_linear_data(skb,
> - rx_q->
> - rx_skbuff[entry]->data,
> - frame_len);
> -
> - skb_put(skb, frame_len);
> - dma_sync_single_for_device(priv->device,
> - rx_q->rx_skbuff_dma
> - [entry], frame_len,
> - DMA_FROM_DEVICE);
> - } else {
> - skb = rx_q->rx_skbuff[entry];
> - if (unlikely(!skb)) {
> - if (net_ratelimit())
> - netdev_err(priv->dev,
> - "%s: Inconsistent Rx chain\n",
> - priv->dev->name);
> - priv->dev->stats.rx_dropped++;
> - continue;
> - }
> - prefetch(skb->data - NET_IP_ALIGN);
> - rx_q->rx_skbuff[entry] = NULL;
> - rx_q->rx_zeroc_thresh++;
> -
> - skb_put(skb, frame_len);
> - dma_unmap_single(priv->device,
> - rx_q->rx_skbuff_dma[entry],
> - priv->dma_buf_sz,
> - DMA_FROM_DEVICE);
> + skb = netdev_alloc_skb_ip_align(priv->dev, frame_len);
> + if (unlikely(!skb)) {
> + priv->dev->stats.rx_dropped++;
> + continue;
> }
>
> + dma_sync_single_for_cpu(priv->device, buf->addr,
> + frame_len, DMA_FROM_DEVICE);
> + skb_copy_to_linear_data(skb, page_address(buf->page),
> + frame_len);
> + skb_put(skb, frame_len);
> +
> if (netif_msg_pktdata(priv)) {
> netdev_dbg(priv->dev, "frame received (%dbytes)",
> frame_len);
> @@ -3547,6 +3456,9 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
>
> napi_gro_receive(&ch->rx_napi, skb);
>
> + page_pool_recycle_direct(rx_q->page_pool, buf->page);
> + buf->page = NULL;
> +
> priv->dev->stats.rx_packets++;
> priv->dev->stats.rx_bytes += frame_len;
> }
> --
> 2.7.4


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