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mlx4_en: Moving to Interrupts for TX completions
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Moving to interrupts instead of polling fpr TX completions
Avoiding situations where skb can be held in by the driver for
a long time (till timer expires).
The change is also necessary for supporting BQL.

Removing comp_lock that was required because we could handle TX
completions from several contexts: Interrupts, timer, polling.
Now there is only interrupts

Signed-off-by: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Yevgeny Petrilin authored and David S. Miller committed Apr 24, 2012
1 parent a19a848 commit e22979d
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Showing 4 changed files with 9 additions and 74 deletions.
14 changes: 3 additions & 11 deletions drivers/net/ethernet/mellanox/mlx4/en_cq.c
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Original file line number Diff line number Diff line change
Expand Up @@ -124,11 +124,7 @@ int mlx4_en_activate_cq(struct mlx4_en_priv *priv, struct mlx4_en_cq *cq,
cq->mcq.comp = cq->is_tx ? mlx4_en_tx_irq : mlx4_en_rx_irq;
cq->mcq.event = mlx4_en_cq_event;

if (cq->is_tx) {
init_timer(&cq->timer);
cq->timer.function = mlx4_en_poll_tx_cq;
cq->timer.data = (unsigned long) cq;
} else {
if (!cq->is_tx) {
netif_napi_add(cq->dev, &cq->napi, mlx4_en_poll_rx_cq, 64);
napi_enable(&cq->napi);
}
Expand All @@ -151,16 +147,12 @@ void mlx4_en_destroy_cq(struct mlx4_en_priv *priv, struct mlx4_en_cq *cq)

void mlx4_en_deactivate_cq(struct mlx4_en_priv *priv, struct mlx4_en_cq *cq)
{
struct mlx4_en_dev *mdev = priv->mdev;

if (cq->is_tx)
del_timer(&cq->timer);
else {
if (!cq->is_tx) {
napi_disable(&cq->napi);
netif_napi_del(&cq->napi);
}

mlx4_cq_free(mdev->dev, &cq->mcq);
mlx4_cq_free(priv->mdev->dev, &cq->mcq);
}

/* Set rx cq moderation parameters */
Expand Down
4 changes: 4 additions & 0 deletions drivers/net/ethernet/mellanox/mlx4/en_netdev.c
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Original file line number Diff line number Diff line change
Expand Up @@ -667,6 +667,10 @@ int mlx4_en_start_port(struct net_device *dev)
mlx4_en_deactivate_cq(priv, cq);
goto tx_err;
}

/* Arm CQ for TX completions */
mlx4_en_arm_cq(priv, cq);

/* Set initial ownership of all Tx TXBBs to SW (1) */
for (j = 0; j < tx_ring->buf_size; j += STAMP_STRIDE)
*((u32 *) (tx_ring->buf + j)) = 0xffffffff;
Expand Down
59 changes: 1 addition & 58 deletions drivers/net/ethernet/mellanox/mlx4/en_tx.c
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Original file line number Diff line number Diff line change
Expand Up @@ -67,8 +67,6 @@ int mlx4_en_create_tx_ring(struct mlx4_en_priv *priv,

inline_thold = min(inline_thold, MAX_INLINE);

spin_lock_init(&ring->comp_lock);

tmp = size * sizeof(struct mlx4_en_tx_info);
ring->tx_info = vmalloc(tmp);
if (!ring->tx_info)
Expand Down Expand Up @@ -377,41 +375,12 @@ void mlx4_en_tx_irq(struct mlx4_cq *mcq)
{
struct mlx4_en_cq *cq = container_of(mcq, struct mlx4_en_cq, mcq);
struct mlx4_en_priv *priv = netdev_priv(cq->dev);
struct mlx4_en_tx_ring *ring = &priv->tx_ring[cq->ring];

if (!spin_trylock(&ring->comp_lock))
return;
mlx4_en_process_tx_cq(cq->dev, cq);
mod_timer(&cq->timer, jiffies + 1);
spin_unlock(&ring->comp_lock);
mlx4_en_arm_cq(priv, cq);
}


void mlx4_en_poll_tx_cq(unsigned long data)
{
struct mlx4_en_cq *cq = (struct mlx4_en_cq *) data;
struct mlx4_en_priv *priv = netdev_priv(cq->dev);
struct mlx4_en_tx_ring *ring = &priv->tx_ring[cq->ring];
u32 inflight;

INC_PERF_COUNTER(priv->pstats.tx_poll);

if (!spin_trylock_irq(&ring->comp_lock)) {
mod_timer(&cq->timer, jiffies + MLX4_EN_TX_POLL_TIMEOUT);
return;
}
mlx4_en_process_tx_cq(cq->dev, cq);
inflight = (u32) (ring->prod - ring->cons - ring->last_nr_txbb);

/* If there are still packets in flight and the timer has not already
* been scheduled by the Tx routine then schedule it here to guarantee
* completion processing of these packets */
if (inflight && priv->port_up)
mod_timer(&cq->timer, jiffies + MLX4_EN_TX_POLL_TIMEOUT);

spin_unlock_irq(&ring->comp_lock);
}

static struct mlx4_en_tx_desc *mlx4_en_bounce_to_desc(struct mlx4_en_priv *priv,
struct mlx4_en_tx_ring *ring,
u32 index,
Expand Down Expand Up @@ -440,25 +409,6 @@ static struct mlx4_en_tx_desc *mlx4_en_bounce_to_desc(struct mlx4_en_priv *priv,
return ring->buf + index * TXBB_SIZE;
}

static inline void mlx4_en_xmit_poll(struct mlx4_en_priv *priv, int tx_ind)
{
struct mlx4_en_cq *cq = &priv->tx_cq[tx_ind];
struct mlx4_en_tx_ring *ring = &priv->tx_ring[tx_ind];
unsigned long flags;

/* If we don't have a pending timer, set one up to catch our recent
post in case the interface becomes idle */
if (!timer_pending(&cq->timer))
mod_timer(&cq->timer, jiffies + MLX4_EN_TX_POLL_TIMEOUT);

/* Poll the CQ every mlx4_en_TX_MODER_POLL packets */
if ((++ring->poll_cnt & (MLX4_EN_TX_POLL_MODER - 1)) == 0)
if (spin_trylock_irqsave(&ring->comp_lock, flags)) {
mlx4_en_process_tx_cq(priv->dev, cq);
spin_unlock_irqrestore(&ring->comp_lock, flags);
}
}

static int is_inline(struct sk_buff *skb, void **pfrag)
{
void *ptr;
Expand Down Expand Up @@ -590,7 +540,6 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
struct mlx4_en_priv *priv = netdev_priv(dev);
struct mlx4_en_dev *mdev = priv->mdev;
struct mlx4_en_tx_ring *ring;
struct mlx4_en_cq *cq;
struct mlx4_en_tx_desc *tx_desc;
struct mlx4_wqe_data_seg *data;
struct skb_frag_struct *frag;
Expand Down Expand Up @@ -638,9 +587,6 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
ring->blocked = 1;
priv->port_stats.queue_stopped++;

/* Use interrupts to find out when queue opened */
cq = &priv->tx_cq[tx_ind];
mlx4_en_arm_cq(priv, cq);
return NETDEV_TX_BUSY;
}

Expand Down Expand Up @@ -788,9 +734,6 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
iowrite32be(ring->doorbell_qpn, ring->bf.uar->map + MLX4_SEND_DOORBELL);
}

/* Poll CQ here */
mlx4_en_xmit_poll(priv, tx_ind);

return NETDEV_TX_OK;

tx_drop:
Expand Down
6 changes: 1 addition & 5 deletions drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -122,7 +122,7 @@ enum {
#define MLX4_EN_RX_COAL_TARGET 44
#define MLX4_EN_RX_COAL_TIME 0x10

#define MLX4_EN_TX_COAL_PKTS 5
#define MLX4_EN_TX_COAL_PKTS 16
#define MLX4_EN_TX_COAL_TIME 0x80

#define MLX4_EN_RX_RATE_LOW 400000
Expand Down Expand Up @@ -255,7 +255,6 @@ struct mlx4_en_tx_ring {
unsigned long bytes;
unsigned long packets;
unsigned long tx_csum;
spinlock_t comp_lock;
struct mlx4_bf bf;
bool bf_enabled;
};
Expand Down Expand Up @@ -308,8 +307,6 @@ struct mlx4_en_cq {
spinlock_t lock;
struct net_device *dev;
struct napi_struct napi;
/* Per-core Tx cq processing support */
struct timer_list timer;
int size;
int buf_size;
unsigned vector;
Expand Down Expand Up @@ -530,7 +527,6 @@ void mlx4_en_deactivate_cq(struct mlx4_en_priv *priv, struct mlx4_en_cq *cq);
int mlx4_en_set_cq_moder(struct mlx4_en_priv *priv, struct mlx4_en_cq *cq);
int mlx4_en_arm_cq(struct mlx4_en_priv *priv, struct mlx4_en_cq *cq);

void mlx4_en_poll_tx_cq(unsigned long data);
void mlx4_en_tx_irq(struct mlx4_cq *mcq);
u16 mlx4_en_select_queue(struct net_device *dev, struct sk_buff *skb);
netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev);
Expand Down

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