[net-next,v3,4/4] octeon_ep: remove atomic variable usage in Tx data path
Commit Message
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: Shinas Rasheed <srasheed@marvell.com>
---
V3:
- No changes.
V2: https://lore.kernel.org/all/20231024145119.2366588-5-srasheed@marvell.com/
- No changes.
V1: https://lore.kernel.org/all/20231023114449.2362147-4-srasheed@marvell.com/
drivers/net/ethernet/marvell/octeon_ep/octep_config.h | 1 +
drivers/net/ethernet/marvell/octeon_ep/octep_main.c | 9 +++------
drivers/net/ethernet/marvell/octeon_ep/octep_main.h | 9 +++++++++
drivers/net/ethernet/marvell/octeon_ep/octep_tx.c | 5 +----
drivers/net/ethernet/marvell/octeon_ep/octep_tx.h | 3 ---
5 files changed, 14 insertions(+), 13 deletions(-)
@@ -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
@@ -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
@@ -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
@@ -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));
}
@@ -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;