[email protected] writes:
> From: Sekhar Nori <[email protected]>
>
> The skb data allocated for packet data received is 4 byte aligned.
>
> Unfortunately, this causes non-32bit aligned accesses in IP stack because
> the MAC header is non-word aligned (14 bytes).
>
> The result can be observed by looking at /proc/cpu/alignment while the
> device is over network.
>
> Doing an skb_reserve(NET_IP_ALIGN) as other driver do fixed the issue.
>
> A quick performance test over lab network using iperf on DM6446 EVM showed
> an increase in bandwidth from 60Mbits/s to 70Mbits/s.
>
> Signed-off-by: Steve Chen <[email protected]>
> Signed-off-by: Sekhar Nori <[email protected]>
> ---
> This patch depends on the "EMAC: remove "extra" bytes provision in rx buffer"
> patch submitted earlier
Thanks, both are now pushed.
Kevin
> drivers/net/davinci_emac.c | 6 +++---
> 1 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/davinci_emac.c b/drivers/net/davinci_emac.c
> index 36a9aba..a766066 100644
> --- a/drivers/net/davinci_emac.c
> +++ b/drivers/net/davinci_emac.c
> @@ -1558,6 +1558,7 @@ static void *emac_net_alloc_rx_buf(struct emac_priv
> *priv, int buf_size,
>
> /* set device pointer in skb and reserve space for extra bytes */
> p_skb->dev = ndev;
> + skb_reserve(p_skb, NET_IP_ALIGN);
> *data_token = (void *) p_skb;
> EMAC_CACHE_WRITEBACK_INVALIDATE((unsigned long)p_skb->data, buf_size);
> return p_skb->data;
> @@ -1986,8 +1987,7 @@ static int emac_rx_bdproc(struct emac_priv *priv, u32
> ch, u32 budget,
> ((frame_status & EMAC_CPPI_OWNERSHIP_BIT) == 0) &&
> (pkts_processed < budget)) {
>
> - new_buffer = emac_net_alloc_rx_buf(priv,
> - EMAC_DEF_MAX_FRAME_SIZE,
> + new_buffer = emac_net_alloc_rx_buf(priv, rxch->buf_size,
> &new_buf_token, EMAC_DEF_RX_CH);
> if (unlikely(NULL == new_buffer)) {
> ++rxch->out_of_rx_buffers;
> @@ -2408,7 +2408,7 @@ static int emac_dev_open(struct net_device *ndev)
> ndev->dev_addr[cnt] = priv->mac_addr[cnt];
>
> /* Configuration items */
> - priv->rx_buf_size = EMAC_DEF_MAX_FRAME_SIZE;
> + priv->rx_buf_size = EMAC_DEF_MAX_FRAME_SIZE + NET_IP_ALIGN;
>
> /* Clear basic hardware */
> for (ch = 0; ch < EMAC_MAX_TXRX_CHANNELS; ch++) {
> --
> 1.6.0.3
>
> _______________________________________________
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> http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source
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