sfc: allocate more RX buffers per page

Allocating 2 buffers per page is insanely inefficient when MTU is 1500
and PAGE_SIZE is 64K (as it usually is on POWER).  Allocate as many as
we can fit, and choose the refill batch size at run-time so that we
still always use a whole page at once.

[bwh: Fix loop condition to allow for compound pages; rebase]
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

1 files changed, 11 insertions, 7 deletions

diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index a70c458f3cef..f050248e9fba 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -643,10 +643,6 @@ static void efx_start_datapath(struct efx_nic *efx)
         if (rx_buf_len <= PAGE_SIZE) {
                 efx->rx_scatter = false;
                 efx->rx_buffer_order = 0;
-                if (rx_buf_len <= PAGE_SIZE / 2)
-                        efx->rx_buffer_truesize = PAGE_SIZE / 2;
-                else
-                        efx->rx_buffer_truesize = PAGE_SIZE;
         } else if (efx->type->can_rx_scatter) {
                 BUILD_BUG_ON(sizeof(struct efx_rx_page_state) +
                              EFX_PAGE_IP_ALIGN + EFX_RX_USR_BUF_SIZE >
@@ -654,14 +650,22 @@ static void efx_start_datapath(struct efx_nic *efx)
                 efx->rx_scatter = true;
                 efx->rx_dma_len = EFX_RX_USR_BUF_SIZE;
                 efx->rx_buffer_order = 0;
-                efx->rx_buffer_truesize = PAGE_SIZE / 2;
         } else {
                 efx->rx_scatter = false;
                 efx->rx_buffer_order = get_order(rx_buf_len);
-                efx->rx_buffer_truesize = PAGE_SIZE << efx->rx_buffer_order;
         }
 
-        efx->rx_bufs_per_page = (rx_buf_len <= PAGE_SIZE / 2) ? 2 : 1;
+        efx_rx_config_page_split(efx);
+        if (efx->rx_buffer_order)
+                netif_dbg(efx, drv, efx->net_dev,
+                          "RX buf len=%u; page order=%u batch=%u\n",
+                          efx->rx_dma_len, efx->rx_buffer_order,
+                          efx->rx_pages_per_batch);
+        else
+                netif_dbg(efx, drv, efx->net_dev,
+                          "RX buf len=%u step=%u bpp=%u; page batch=%u\n",
+                          efx->rx_dma_len, efx->rx_page_buf_step,
+                          efx->rx_bufs_per_page, efx->rx_pages_per_batch);
 
         /* RX filters also have scatter-enabled flags */
         if (efx->rx_scatter != old_rx_scatter)