On Sat, Jul 20, 2024 at 07:46:18PM +0300, Elad Yifee wrote:
> Utilize kernel prefetch methods for faster cache line access.
> This change boosts driver performance,
> allowing the CPU to handle about 5% more packets/sec.
Nit: It'd be great to see before/after numbers and/or an explanation of
how you measured this in the commit message.
> Signed-off-by: Elad Yifee <eladwf@xxxxxxxxx>
> ---
> drivers/net/ethernet/mediatek/mtk_eth_soc.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> index 0cc2dd85652f..1a0704166103 100644
> --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> @@ -1963,6 +1963,7 @@ static u32 mtk_xdp_run(struct mtk_eth *eth, struct mtk_rx_ring *ring,
> if (!prog)
> goto out;
>
> + prefetchw(xdp->data_hard_start);
Is there any reason to mix net_prefetch (as you have below) with
prefetch and prefetchw ?
IMHO: you should consider using net_prefetch and net_prefetchw
everywhere instead of using both in your code.
> act = bpf_prog_run_xdp(prog, xdp);
> switch (act) {
> case XDP_PASS:
> @@ -2039,7 +2040,7 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
> idx = NEXT_DESP_IDX(ring->calc_idx, ring->dma_size);
> rxd = ring->dma + idx * eth->soc->rx.desc_size;
> data = ring->data[idx];
> -
> + prefetch(rxd);
Maybe net_prefetch instead, as mentioned above?
> if (!mtk_rx_get_desc(eth, &trxd, rxd))
> break;
>
> @@ -2105,6 +2106,7 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
> if (ret != XDP_PASS)
> goto skip_rx;
>
> + net_prefetch(xdp.data_meta);
> skb = build_skb(data, PAGE_SIZE);
> if (unlikely(!skb)) {
> page_pool_put_full_page(ring->page_pool,
> @@ -2113,6 +2115,7 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
> goto skip_rx;
> }
>
> + prefetchw(skb->data);
Maybe net_prefetchw instead, as mentioned above?
> skb_reserve(skb, xdp.data - xdp.data_hard_start);
> skb_put(skb, xdp.data_end - xdp.data);
> skb_mark_for_recycle(skb);
> @@ -2143,6 +2146,7 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
> dma_unmap_single(eth->dma_dev, ((u64)trxd.rxd1 | addr64),
> ring->buf_size, DMA_FROM_DEVICE);
>
> + net_prefetch(data);
> skb = build_skb(data, ring->frag_size);
> if (unlikely(!skb)) {
> netdev->stats.rx_dropped++;
> @@ -2150,6 +2154,7 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
> goto skip_rx;
> }
>
> + prefetchw(skb->data);
Maybe net_prefetchw instead, as mentioned above?
