Commit 2f128eb3 authored by Matteo Croce's avatar Matteo Croce Committed by David S. Miller
Browse files

mvpp2: prefetch page 



Most of the time during the RX is caused by the compound_head() call
done at the end of the RX loop:

       │     build_skb():
       [...]
       │     static inline struct page *compound_head(struct page *page)
       │     {
       │     unsigned long head = READ_ONCE(page->compound_head);
 65.23 │       ldr  x2, [x1, #8]

Prefetch the page struct as soon as possible, to speedup the RX path
noticeabily by a ~3-4% packet rate in a drop test.

       │     build_skb():
       [...]
       │     static inline struct page *compound_head(struct page *page)
       │     {
       │     unsigned long head = READ_ONCE(page->compound_head);
 17.92 │       ldr  x2, [x1, #8]

Signed-off-by: default avatarMatteo Croce <mcroce@microsoft.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d8ea89fe

drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c

+7 −3
Original line number Diff line number Diff line
@@ -3900,15 +3900,19 @@ static int mvpp2_rx(struct mvpp2_port *port, struct napi_struct *napi, 
		phys_addr_t phys_addr;

		u32 rx_status, timestamp;

		int pool, rx_bytes, err, ret;

		struct page *page;

		void *data;



		phys_addr = mvpp2_rxdesc_cookie_get(port, rx_desc);

		data = (void *)phys_to_virt(phys_addr);

		page = virt_to_page(data);

		prefetch(page);



		rx_done++;

		rx_status = mvpp2_rxdesc_status_get(port, rx_desc);

		rx_bytes = mvpp2_rxdesc_size_get(port, rx_desc);

		rx_bytes -= MVPP2_MH_SIZE;

		dma_addr = mvpp2_rxdesc_dma_addr_get(port, rx_desc);

		phys_addr = mvpp2_rxdesc_cookie_get(port, rx_desc);

		data = (void *)phys_to_virt(phys_addr);



		pool = (rx_status & MVPP2_RXD_BM_POOL_ID_MASK) >>

			MVPP2_RXD_BM_POOL_ID_OFFS;
@@ -3997,7 +4001,7 @@ static int mvpp2_rx(struct mvpp2_port *port, struct napi_struct *napi, 
		}



		if (pp)

			skb_mark_for_recycle(skb, virt_to_page(data), pp);

			skb_mark_for_recycle(skb, page, pp);

		else

			dma_unmap_single_attrs(dev->dev.parent, dma_addr,

					       bm_pool->buf_size, DMA_FROM_DEVICE,