Commit dc9c02b7 authored by Shinas Rasheed's avatar Shinas Rasheed Committed by David S. Miller
Browse files

octeon_ep: remove atomic variable usage in Tx data path 



Replace atomic variable "instr_pending" which represents number of
posted tx instructions pending completion, with host_write_idx and
flush_index variables in the xmit and completion processing respectively.

Signed-off-by: default avatarShinas Rasheed <srasheed@marvell.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 373d9a55

drivers/net/ethernet/marvell/octeon_ep/octep_config.h

+1 −0
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
#define OCTEP_64BYTE_INSTR  64



/* Tx Queue: maximum descriptors per ring */

/* This needs to be a power of 2 */

#define OCTEP_IQ_MAX_DESCRIPTORS    1024

/* Minimum input (Tx) requests to be enqueued to ring doorbell */

#define OCTEP_DB_MIN                8

drivers/net/ethernet/marvell/octeon_ep/octep_main.c

+3 −6
Original line number Diff line number Diff line
@@ -777,7 +777,7 @@ static int octep_stop(struct net_device *netdev) 
 */

static inline int octep_iq_full_check(struct octep_iq *iq)

{

	if (likely((iq->max_count - atomic_read(&iq->instr_pending)) >=

	if (likely((IQ_INSTR_SPACE(iq)) >

		   OCTEP_WAKE_QUEUE_THRESHOLD))

		return 0;
@@ -794,7 +794,7 @@ static inline int octep_iq_full_check(struct octep_iq *iq) 
	/* check again and restart the queue, in case NAPI has just freed

	 * enough Tx ring entries.

	 */

	if (unlikely((iq->max_count - atomic_read(&iq->instr_pending)) >=

	if (unlikely(IQ_INSTR_SPACE(iq) >

		     OCTEP_WAKE_QUEUE_THRESHOLD)) {

		netif_start_subqueue(iq->netdev, iq->q_no);

		iq->stats.restart_cnt++;
@@ -903,12 +903,9 @@ static netdev_tx_t octep_start_xmit(struct sk_buff *skb, 
	__netdev_tx_sent_queue(iq->netdev_q, skb->len, xmit_more);



	skb_tx_timestamp(skb);

	atomic_inc(&iq->instr_pending);

	iq->fill_cnt++;

	wi++;

	if (wi == iq->max_count)

		wi = 0;

	iq->host_write_index = wi;

	iq->host_write_index = wi & iq->ring_size_mask;



	/* octep_iq_full_check stops the queue and returns

	 * true if so, in case the queue has become full

drivers/net/ethernet/marvell/octeon_ep/octep_main.h

+9 −0
Original line number Diff line number Diff line
@@ -40,6 +40,15 @@ 
#define  OCTEP_OQ_INTR_RESEND_BIT  59



#define  OCTEP_MMIO_REGIONS     3



#define  IQ_INSTR_PENDING(iq)  ({ typeof(iq) iq__ = (iq); \

				  ((iq__)->host_write_index - (iq__)->flush_index) & \

				  (iq__)->ring_size_mask; \

				})

#define  IQ_INSTR_SPACE(iq)    ({ typeof(iq) iq_ = (iq); \

				  (iq_)->max_count - IQ_INSTR_PENDING(iq_); \

				})



/* PCI address space mapping information.

 * Each of the 3 address spaces given by BAR0, BAR2 and BAR4 of

 * Octeon gets mapped to different physical address spaces in

drivers/net/ethernet/marvell/octeon_ep/octep_tx.c

+1 −4
Original line number Diff line number Diff line
@@ -21,7 +21,6 @@ static void octep_iq_reset_indices(struct octep_iq *iq) 
	iq->flush_index = 0;

	iq->pkts_processed = 0;

	iq->pkt_in_done = 0;

	atomic_set(&iq->instr_pending, 0);

}



/**
@@ -82,7 +81,6 @@ int octep_iq_process_completions(struct octep_iq *iq, u16 budget) 
	}



	iq->pkts_processed += compl_pkts;

	atomic_sub(compl_pkts, &iq->instr_pending);

	iq->stats.instr_completed += compl_pkts;

	iq->stats.bytes_sent += compl_bytes;

	iq->stats.sgentry_sent += compl_sg;
@@ -91,7 +89,7 @@ int octep_iq_process_completions(struct octep_iq *iq, u16 budget) 
	netdev_tx_completed_queue(iq->netdev_q, compl_pkts, compl_bytes);



	if (unlikely(__netif_subqueue_stopped(iq->netdev, iq->q_no)) &&

	    ((iq->max_count - atomic_read(&iq->instr_pending)) >

	    (IQ_INSTR_SPACE(iq) >

	     OCTEP_WAKE_QUEUE_THRESHOLD))

		netif_wake_subqueue(iq->netdev, iq->q_no);

	return !budget;
@@ -144,7 +142,6 @@ static void octep_iq_free_pending(struct octep_iq *iq) 
		dev_kfree_skb_any(skb);

	}



	atomic_set(&iq->instr_pending, 0);

	iq->flush_index = fi;

	netdev_tx_reset_queue(netdev_get_tx_queue(iq->netdev, iq->q_no));

}

drivers/net/ethernet/marvell/octeon_ep/octep_tx.h

+0 −3
Original line number Diff line number Diff line
@@ -172,9 +172,6 @@ struct octep_iq { 
	/* Statistics for this input queue. */

	struct octep_iq_stats stats;



	/* This field keeps track of the instructions pending in this queue. */

	atomic_t instr_pending;



	/* Pointer to the Virtual Base addr of the input ring. */

	struct octep_tx_desc_hw *desc_ring;