Commit 635372ad authored Sep 03, 2016 by Sean Wang Committed by David S. Miller Sep 06, 2016

net: ethernet: mediatek: enhance RX path by reducing the frequency of the memory barrier used



The patch makes move wmb() to outside the loop that could help
RX path handling more faster although that RX descriptors aren't
freed for DMA to use as soon as possible, but based on my experiment
and the result shows it still can reach about 943Mbpis without
performance drop that is tested based on the setup with one port
using Giga PHY and 256 RX descriptors for DMA to move.

Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 0da4d283

drivers/net/ethernet/mediatek/mtk_eth_soc.c

+6 −5

Original line number	Diff line number	Diff line
		@@ -895,13 +895,14 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
		rxd->rxd2 = RX_DMA_PLEN0(ring->buf_size);

		ring->calc_idx = idx;

		done++;
		}
		/* make sure that all changes to the dma ring are flushed before
		* we continue
		*/
		wmb();
		mtk_w32(eth, ring->calc_idx, MTK_PRX_CRX_IDX0);
		done++;
		}

		if (done < budget)
		mtk_w32(eth, MTK_RX_DONE_INT, MTK_PDMA_INT_STATUS);