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Date: Wed, 8 Oct 2014 10:02:58 -0700 From: Greg Rose <gregory.v.rose@...el.com> To: Eric Dumazet <eric.dumazet@...il.com> Cc: David Miller <davem@...emloft.net>, netdev <netdev@...r.kernel.org>, Daniel Borkmann <dborkman@...hat.com>, Jeff Kirsher <jeffrey.t.kirsher@...el.com> Subject: Re: [PATCH net-next] i40e: skb->xmit_more support On Tue, 7 Oct 2014 13:30:23 -0700 Eric Dumazet <eric.dumazet@...il.com> wrote: > From: Eric Dumazet <edumazet@...gle.com> > > Support skb->xmit_more in i40e is straightforward : we need to move > around i40e_maybe_stop_tx() call to correctly test > netif_xmit_stopped() before taking the decision to not kick the NIC. > > Signed-off-by: Eric Dumazet <edumazet@...gle.com> Looks good to me. - Greg > --- > drivers/net/ethernet/intel/i40e/i40e_txrx.c | 90 +++++++++--------- > 1 file changed, 46 insertions(+), 44 deletions(-) > > diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c > b/drivers/net/ethernet/intel/i40e/i40e_txrx.c index > 267992b3de8a..3195d82e4942 100644 --- > a/drivers/net/ethernet/intel/i40e/i40e_txrx.c +++ > b/drivers/net/ethernet/intel/i40e/i40e_txrx.c @@ -2053,6 +2053,47 @@ > static void i40e_create_tx_ctx(struct i40e_ring *tx_ring, } > > /** > + * __i40e_maybe_stop_tx - 2nd level check for tx stop conditions > + * @tx_ring: the ring to be checked > + * @size: the size buffer we want to assure is available > + * > + * Returns -EBUSY if a stop is needed, else 0 > + **/ > +static inline int __i40e_maybe_stop_tx(struct i40e_ring *tx_ring, > int size) +{ > + netif_stop_subqueue(tx_ring->netdev, tx_ring->queue_index); > + /* Memory barrier before checking head and tail */ > + smp_mb(); > + > + /* Check again in a case another CPU has just made room > available. */ > + if (likely(I40E_DESC_UNUSED(tx_ring) < size)) > + return -EBUSY; > + > + /* A reprieve! - use start_queue because it doesn't call > schedule */ > + netif_start_subqueue(tx_ring->netdev, tx_ring->queue_index); > + ++tx_ring->tx_stats.restart_queue; > + return 0; > +} > + > +/** > + * i40e_maybe_stop_tx - 1st level check for tx stop conditions > + * @tx_ring: the ring to be checked > + * @size: the size buffer we want to assure is available > + * > + * Returns 0 if stop is not needed > + **/ > +#ifdef I40E_FCOE > +int i40e_maybe_stop_tx(struct i40e_ring *tx_ring, int size) > +#else > +static int i40e_maybe_stop_tx(struct i40e_ring *tx_ring, int size) > +#endif > +{ > + if (likely(I40E_DESC_UNUSED(tx_ring) >= size)) > + return 0; > + return __i40e_maybe_stop_tx(tx_ring, size); > +} > + > +/** > * i40e_tx_map - Build the Tx descriptor > * @tx_ring: ring to send buffer on > * @skb: send buffer > @@ -2195,8 +2236,12 @@ static void i40e_tx_map(struct i40e_ring > *tx_ring, struct sk_buff *skb, > tx_ring->next_to_use = i; > > + i40e_maybe_stop_tx(tx_ring, DESC_NEEDED); > /* notify HW of packet */ > - writel(i, tx_ring->tail); > + if (!skb->xmit_more || > + netif_xmit_stopped(netdev_get_tx_queue(tx_ring->netdev, > + > tx_ring->queue_index))) > + writel(i, tx_ring->tail); > > return; > > @@ -2218,47 +2263,6 @@ dma_error: > } > > /** > - * __i40e_maybe_stop_tx - 2nd level check for tx stop conditions > - * @tx_ring: the ring to be checked > - * @size: the size buffer we want to assure is available > - * > - * Returns -EBUSY if a stop is needed, else 0 > - **/ > -static inline int __i40e_maybe_stop_tx(struct i40e_ring *tx_ring, > int size) -{ > - netif_stop_subqueue(tx_ring->netdev, tx_ring->queue_index); > - /* Memory barrier before checking head and tail */ > - smp_mb(); > - > - /* Check again in a case another CPU has just made room > available. */ > - if (likely(I40E_DESC_UNUSED(tx_ring) < size)) > - return -EBUSY; > - > - /* A reprieve! - use start_queue because it doesn't call > schedule */ > - netif_start_subqueue(tx_ring->netdev, tx_ring->queue_index); > - ++tx_ring->tx_stats.restart_queue; > - return 0; > -} > - > -/** > - * i40e_maybe_stop_tx - 1st level check for tx stop conditions > - * @tx_ring: the ring to be checked > - * @size: the size buffer we want to assure is available > - * > - * Returns 0 if stop is not needed > - **/ > -#ifdef I40E_FCOE > -int i40e_maybe_stop_tx(struct i40e_ring *tx_ring, int size) > -#else > -static int i40e_maybe_stop_tx(struct i40e_ring *tx_ring, int size) > -#endif > -{ > - if (likely(I40E_DESC_UNUSED(tx_ring) >= size)) > - return 0; > - return __i40e_maybe_stop_tx(tx_ring, size); > -} > - > -/** > * i40e_xmit_descriptor_count - calculate number of tx descriptors > needed > * @skb: send buffer > * @tx_ring: ring to send buffer on > @@ -2372,8 +2376,6 @@ static netdev_tx_t i40e_xmit_frame_ring(struct > sk_buff *skb, i40e_tx_map(tx_ring, skb, first, tx_flags, hdr_len, > td_cmd, td_offset); > > - i40e_maybe_stop_tx(tx_ring, DESC_NEEDED); > - > return NETDEV_TX_OK; > > out_drop: > > > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@...r.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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