lan966x: Don't use xdp_frame when action is XDP_TX

When the action of an xdp program was XDP_TX, lan966x was creating
a xdp_frame and use this one to send the frame back. But it is also
possible to send back the frame without needing a xdp_frame, because
it is possible to send it back using the page.
And then once the frame is transmitted is possible to use directly
page_pool_recycle_direct as lan966x is using page pools.
This would save some CPU usage on this path, which results in higher
number of transmitted frames. Bellow are the statistics:
Frame size:    Improvement:
64                ~8%
256              ~11%
512               ~8%
1000              ~0%
1500              ~0%

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Link: https://lore.kernel.org/r/20230422142344.3630602-1-horatiu.vultur@microchip.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c b/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c
index 2ed76bb..bd72fbc 100644 (file)
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c
@@ -390,6 +390,7 @@ static void lan966x_fdma_stop_netdev(struct lan966x *lan966x)
 static void lan966x_fdma_tx_clear_buf(struct lan966x *lan966x, int weight)
 {
        struct lan966x_tx *tx = &lan966x->tx;
+       struct lan966x_rx *rx = &lan966x->rx;
        struct lan966x_tx_dcb_buf *dcb_buf;
        struct xdp_frame_bulk bq;
        struct lan966x_db *db;
@@ -432,7 +433,8 @@ static void lan966x_fdma_tx_clear_buf(struct lan966x *lan966x, int weight)
                        if (dcb_buf->xdp_ndo)
                                xdp_return_frame_bulk(dcb_buf->data.xdpf, &bq);
                        else
-                               xdp_return_frame_rx_napi(dcb_buf->data.xdpf);
+                               page_pool_recycle_direct(rx->page_pool,
+                                                        dcb_buf->data.page);
                }
 
                clear = true;
@@ -699,15 +701,14 @@ static void lan966x_fdma_tx_start(struct lan966x_tx *tx, int next_to_use)
        tx->last_in_use = next_to_use;
 }
 
-int lan966x_fdma_xmit_xdpf(struct lan966x_port *port,
-                          struct xdp_frame *xdpf,
-                          struct page *page,
-                          bool dma_map)
+int lan966x_fdma_xmit_xdpf(struct lan966x_port *port, void *ptr, u32 len)
 {
        struct lan966x *lan966x = port->lan966x;
        struct lan966x_tx_dcb_buf *next_dcb_buf;
        struct lan966x_tx *tx = &lan966x->tx;
+       struct xdp_frame *xdpf;
        dma_addr_t dma_addr;
+       struct page *page;
        int next_to_use;
        __be32 *ifh;
        int ret = 0;
@@ -722,8 +723,13 @@ int lan966x_fdma_xmit_xdpf(struct lan966x_port *port,
                goto out;
        }
 
+       /* Get the next buffer */
+       next_dcb_buf = &tx->dcbs_buf[next_to_use];
+
        /* Generate new IFH */
-       if (dma_map) {
+       if (!len) {
+               xdpf = ptr;
+
                if (xdpf->headroom < IFH_LEN_BYTES) {
                        ret = NETDEV_TX_OK;
                        goto out;
@@ -743,11 +749,16 @@ int lan966x_fdma_xmit_xdpf(struct lan966x_port *port,
                        goto out;
                }
 
+               next_dcb_buf->data.xdpf = xdpf;
+               next_dcb_buf->len = xdpf->len + IFH_LEN_BYTES;
+
                /* Setup next dcb */
                lan966x_fdma_tx_setup_dcb(tx, next_to_use,
                                          xdpf->len + IFH_LEN_BYTES,
                                          dma_addr);
        } else {
+               page = ptr;
+
                ifh = page_address(page) + XDP_PACKET_HEADROOM;
                memset(ifh, 0x0, sizeof(__be32) * IFH_LEN);
                lan966x_ifh_set_bypass(ifh, 1);
@@ -756,21 +767,21 @@ int lan966x_fdma_xmit_xdpf(struct lan966x_port *port,
                dma_addr = page_pool_get_dma_addr(page);
                dma_sync_single_for_device(lan966x->dev,
                                           dma_addr + XDP_PACKET_HEADROOM,
-                                          xdpf->len + IFH_LEN_BYTES,
+                                          len + IFH_LEN_BYTES,
                                           DMA_TO_DEVICE);
 
+               next_dcb_buf->data.page = page;
+               next_dcb_buf->len = len + IFH_LEN_BYTES;
+
                /* Setup next dcb */
                lan966x_fdma_tx_setup_dcb(tx, next_to_use,
-                                         xdpf->len + IFH_LEN_BYTES,
+                                         len + IFH_LEN_BYTES,
                                          dma_addr + XDP_PACKET_HEADROOM);
        }
 
        /* Fill up the buffer */
-       next_dcb_buf = &tx->dcbs_buf[next_to_use];
        next_dcb_buf->use_skb = false;
-       next_dcb_buf->data.xdpf = xdpf;
-       next_dcb_buf->xdp_ndo = dma_map;
-       next_dcb_buf->len = xdpf->len + IFH_LEN_BYTES;
+       next_dcb_buf->xdp_ndo = !len;
        next_dcb_buf->dma_addr = dma_addr;
        next_dcb_buf->used = true;
        next_dcb_buf->ptp = false;

diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_main.h b/drivers/net/ethernet/microchip/lan966x/lan966x_main.h
index 851afb0..c977c70 100644 (file)
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_main.h
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_main.h
@@ -243,6 +243,7 @@ struct lan966x_tx_dcb_buf {
        union {
                struct sk_buff *skb;
                struct xdp_frame *xdpf;
+               struct page *page;
        } data;
        u32 len;
        u32 used : 1;
@@ -541,10 +542,7 @@ int lan966x_ptp_setup_traps(struct lan966x_port *port, struct ifreq *ifr);
 int lan966x_ptp_del_traps(struct lan966x_port *port);
 
 int lan966x_fdma_xmit(struct sk_buff *skb, __be32 *ifh, struct net_device *dev);
-int lan966x_fdma_xmit_xdpf(struct lan966x_port *port,
-                          struct xdp_frame *frame,
-                          struct page *page,
-                          bool dma_map);
+int lan966x_fdma_xmit_xdpf(struct lan966x_port *port, void *ptr, u32 len);
 int lan966x_fdma_change_mtu(struct lan966x *lan966x);
 void lan966x_fdma_netdev_init(struct lan966x *lan966x, struct net_device *dev);
 void lan966x_fdma_netdev_deinit(struct lan966x *lan966x, struct net_device *dev);

diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_xdp.c b/drivers/net/ethernet/microchip/lan966x/lan966x_xdp.c
index 2e6f486..9ee61db 100644 (file)
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_xdp.c
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_xdp.c
@@ -62,7 +62,7 @@ int lan966x_xdp_xmit(struct net_device *dev,
                struct xdp_frame *xdpf = frames[i];
                int err;
 
-               err = lan966x_fdma_xmit_xdpf(port, xdpf, NULL, true);
+               err = lan966x_fdma_xmit_xdpf(port, xdpf, 0);
                if (err)
                        break;
 
@@ -76,7 +76,6 @@ int lan966x_xdp_run(struct lan966x_port *port, struct page *page, u32 data_len)
 {
        struct bpf_prog *xdp_prog = port->xdp_prog;
        struct lan966x *lan966x = port->lan966x;
-       struct xdp_frame *xdpf;
        struct xdp_buff xdp;
        u32 act;
 
@@ -90,11 +89,8 @@ int lan966x_xdp_run(struct lan966x_port *port, struct page *page, u32 data_len)
        case XDP_PASS:
                return FDMA_PASS;
        case XDP_TX:
-               xdpf = xdp_convert_buff_to_frame(&xdp);
-               if (!xdpf)
-                       return FDMA_DROP;
-
-               return lan966x_fdma_xmit_xdpf(port, xdpf, page, false) ?
+               return lan966x_fdma_xmit_xdpf(port, page,
+                                             data_len - IFH_LEN_BYTES) ?
                       FDMA_DROP : FDMA_TX;
        case XDP_REDIRECT:
                if (xdp_do_redirect(port->dev, &xdp, xdp_prog))