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Date:   Wed, 3 Jul 2019 10:40:51 +0000
From:   Jose Abreu <Jose.Abreu@...opsys.com>
To:     Jose Abreu <Jose.Abreu@...opsys.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Jesper Dangaard Brouer <brouer@...hat.com>
CC:     Joao Pinto <Joao.Pinto@...opsys.com>,
        "David S . Miller" <davem@...emloft.net>,
        Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        Chen-Yu Tsai <wens@...e.org>
Subject: RE: [PATCH net-next 3/3] net: stmmac: Introducing support for Page
 Pool

++ Jesper: Who is most active committer of page pool API (?) ... Can you 
please help review this ?

From: Jose Abreu <joabreu@...opsys.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@...opsys.com>
> Cc: Joao Pinto <jpinto@...opsys.com>
> Cc: David S. Miller <davem@...emloft.net>
> Cc: Giuseppe Cavallaro <peppe.cavallaro@...com>
> Cc: Alexandre Torgue <alexandre.torgue@...com>
> Cc: Maxime Coquelin <mcoquelin.stm32@...il.com>
> Cc: Maxime Ripard <maxime.ripard@...tlin.com>
> Cc: Chen-Yu Tsai <wens@...e.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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