diff options
| -rw-r--r-- | drivers/net/ethernet/sfc/nic.h | 29 | ||||
| -rw-r--r-- | drivers/net/ethernet/sfc/tx.c | 43 |
2 files changed, 43 insertions, 29 deletions
diff --git a/drivers/net/ethernet/sfc/nic.h b/drivers/net/ethernet/sfc/nic.h index 60f85149fc4c..f77cce034ad4 100644 --- a/drivers/net/ethernet/sfc/nic.h +++ b/drivers/net/ethernet/sfc/nic.h @@ -71,9 +71,17 @@ efx_tx_desc(struct efx_tx_queue *tx_queue, unsigned int index) return ((efx_qword_t *) (tx_queue->txd.buf.addr)) + index; } -/* Report whether the NIC considers this TX queue empty, given the - * write_count used for the last doorbell push. May return false - * negative. +/* Get partner of a TX queue, seen as part of the same net core queue */ +static struct efx_tx_queue *efx_tx_queue_partner(struct efx_tx_queue *tx_queue) +{ + if (tx_queue->queue & EFX_TXQ_TYPE_OFFLOAD) + return tx_queue - EFX_TXQ_TYPE_OFFLOAD; + else + return tx_queue + EFX_TXQ_TYPE_OFFLOAD; +} + +/* Report whether this TX queue would be empty for the given write_count. + * May return false negative. */ static inline bool __efx_nic_tx_is_empty(struct efx_tx_queue *tx_queue, unsigned int write_count) @@ -86,9 +94,18 @@ static inline bool __efx_nic_tx_is_empty(struct efx_tx_queue *tx_queue, return ((empty_read_count ^ write_count) & ~EFX_EMPTY_COUNT_VALID) == 0; } -static inline bool efx_nic_tx_is_empty(struct efx_tx_queue *tx_queue) +/* Decide whether we can use TX PIO, ie. write packet data directly into + * a buffer on the device. This can reduce latency at the expense of + * throughput, so we only do this if both hardware and software TX rings + * are empty. This also ensures that only one packet at a time can be + * using the PIO buffer. + */ +static inline bool efx_nic_may_tx_pio(struct efx_tx_queue *tx_queue) { - return __efx_nic_tx_is_empty(tx_queue, tx_queue->write_count); + struct efx_tx_queue *partner = efx_tx_queue_partner(tx_queue); + return tx_queue->piobuf && + __efx_nic_tx_is_empty(tx_queue, tx_queue->insert_count) && + __efx_nic_tx_is_empty(partner, partner->insert_count); } /* Decide whether to push a TX descriptor to the NIC vs merely writing @@ -96,6 +113,8 @@ static inline bool efx_nic_tx_is_empty(struct efx_tx_queue *tx_queue) * descriptor to an empty queue, but is otherwise pointless. Further, * Falcon and Siena have hardware bugs (SF bug 33851) that may be * triggered if we don't check this. + * We use the write_count used for the last doorbell push, to get the + * NIC's view of the tx queue. */ static inline bool efx_nic_may_push_tx_desc(struct efx_tx_queue *tx_queue, unsigned int write_count) diff --git a/drivers/net/ethernet/sfc/tx.c b/drivers/net/ethernet/sfc/tx.c index 320609842211..ee84a90e371c 100644 --- a/drivers/net/ethernet/sfc/tx.c +++ b/drivers/net/ethernet/sfc/tx.c @@ -132,15 +132,6 @@ unsigned int efx_tx_max_skb_descs(struct efx_nic *efx) return max_descs; } -/* Get partner of a TX queue, seen as part of the same net core queue */ -static struct efx_tx_queue *efx_tx_queue_partner(struct efx_tx_queue *tx_queue) -{ - if (tx_queue->queue & EFX_TXQ_TYPE_OFFLOAD) - return tx_queue - EFX_TXQ_TYPE_OFFLOAD; - else - return tx_queue + EFX_TXQ_TYPE_OFFLOAD; -} - static void efx_tx_maybe_stop_queue(struct efx_tx_queue *txq1) { /* We need to consider both queues that the net core sees as one */ @@ -344,6 +335,7 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb) struct efx_nic *efx = tx_queue->efx; struct device *dma_dev = &efx->pci_dev->dev; struct efx_tx_buffer *buffer; + unsigned int old_insert_count = tx_queue->insert_count; skb_frag_t *fragment; unsigned int len, unmap_len = 0; dma_addr_t dma_addr, unmap_addr = 0; @@ -351,7 +343,7 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb) unsigned short dma_flags; int i = 0; - EFX_BUG_ON_PARANOID(tx_queue->write_count != tx_queue->insert_count); + EFX_BUG_ON_PARANOID(tx_queue->write_count > tx_queue->insert_count); if (skb_shinfo(skb)->gso_size) return efx_enqueue_skb_tso(tx_queue, skb); @@ -369,9 +361,8 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb) /* Consider using PIO for short packets */ #ifdef EFX_USE_PIO - if (skb->len <= efx_piobuf_size && tx_queue->piobuf && - efx_nic_tx_is_empty(tx_queue) && - efx_nic_tx_is_empty(efx_tx_queue_partner(tx_queue))) { + if (skb->len <= efx_piobuf_size && !skb->xmit_more && + efx_nic_may_tx_pio(tx_queue)) { buffer = efx_enqueue_skb_pio(tx_queue, skb); dma_flags = EFX_TX_BUF_OPTION; goto finish_packet; @@ -439,13 +430,14 @@ finish_packet: netdev_tx_sent_queue(tx_queue->core_txq, skb->len); + efx_tx_maybe_stop_queue(tx_queue); + /* Pass off to hardware */ - efx_nic_push_buffers(tx_queue); + if (!skb->xmit_more || netif_xmit_stopped(tx_queue->core_txq)) + efx_nic_push_buffers(tx_queue); tx_queue->tx_packets++; - efx_tx_maybe_stop_queue(tx_queue); - return NETDEV_TX_OK; dma_err: @@ -458,7 +450,7 @@ finish_packet: dev_kfree_skb_any(skb); /* Work backwards until we hit the original insert pointer value */ - while (tx_queue->insert_count != tx_queue->write_count) { + while (tx_queue->insert_count != old_insert_count) { unsigned int pkts_compl = 0, bytes_compl = 0; --tx_queue->insert_count; buffer = __efx_tx_queue_get_insert_buffer(tx_queue); @@ -989,12 +981,13 @@ static int efx_tso_put_header(struct efx_tx_queue *tx_queue, /* Remove buffers put into a tx_queue. None of the buffers must have * an skb attached. */ -static void efx_enqueue_unwind(struct efx_tx_queue *tx_queue) +static void efx_enqueue_unwind(struct efx_tx_queue *tx_queue, + unsigned int insert_count) { struct efx_tx_buffer *buffer; /* Work backwards until we hit the original insert pointer value */ - while (tx_queue->insert_count != tx_queue->write_count) { + while (tx_queue->insert_count != insert_count) { --tx_queue->insert_count; buffer = __efx_tx_queue_get_insert_buffer(tx_queue); efx_dequeue_buffer(tx_queue, buffer, NULL, NULL); @@ -1258,13 +1251,14 @@ static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue, struct sk_buff *skb) { struct efx_nic *efx = tx_queue->efx; + unsigned int old_insert_count = tx_queue->insert_count; int frag_i, rc; struct tso_state state; /* Find the packet protocol and sanity-check it */ state.protocol = efx_tso_check_protocol(skb); - EFX_BUG_ON_PARANOID(tx_queue->write_count != tx_queue->insert_count); + EFX_BUG_ON_PARANOID(tx_queue->write_count > tx_queue->insert_count); rc = tso_start(&state, efx, skb); if (rc) @@ -1308,11 +1302,12 @@ static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue, netdev_tx_sent_queue(tx_queue->core_txq, skb->len); - /* Pass off to hardware */ - efx_nic_push_buffers(tx_queue); - efx_tx_maybe_stop_queue(tx_queue); + /* Pass off to hardware */ + if (!skb->xmit_more || netif_xmit_stopped(tx_queue->core_txq)) + efx_nic_push_buffers(tx_queue); + tx_queue->tso_bursts++; return NETDEV_TX_OK; @@ -1336,6 +1331,6 @@ static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue, dma_unmap_single(&efx->pci_dev->dev, state.header_dma_addr, state.header_unmap_len, DMA_TO_DEVICE); - efx_enqueue_unwind(tx_queue); + efx_enqueue_unwind(tx_queue, old_insert_count); return NETDEV_TX_OK; } |