>From 741bc1bfccbfe33cebaceb2e854539946e8ec9fa Mon Sep 17 00:00:00 2001 From: Willy Tarreau Date: Wed, 20 Nov 2013 19:47:11 +0100 Subject: net: mvneta: replace Tx timer with a real interrupt Right now the mvneta driver doesn't handle Tx IRQ, and solely relies on a timer to flush Tx descriptors. This causes jerky output traffic with bursts and pauses, making it difficult to reach line rate with very few streams. It seems that this feature was inherited from the original driver but nothing there mentions any reason for not using the interrupt instead, which the chip supports. Thus, this patch enables Tx interrupts and removes the timer. It does the two at once because it's not really possible to make the two mechanisms coexist, so a split patch doesn't make sense. First tests performed on a Mirabox (Armada 370) show that much less CPU is used when sending traffic. One reason might be that we now call the mvneta_tx_done_gbe() with a mask indicating which queues have been done instead of looping over all of them. The results are quite good, a single TCP stream is now capable of saturating a gigabit link, while a minimum of 12 concurrent streams are needed without the patch. At 1 Gbps with 12 concurrent streams, 60% of the CPU remains idle without the patch, and it grows to 87% with the patch. The connection rate has also increased from 9950 to 10150 connections per second (HTTP requests of empty objects). Signed-off-by: Willy Tarreau Cc: Thomas Petazzoni Cc: Arnaud Ebalard Cc: Eric Dumazet --- drivers/net/ethernet/marvell/mvneta.c | 71 ++++++----------------------------- 1 file changed, 12 insertions(+), 59 deletions(-) diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c index 6630690..def32a8 100644 --- a/drivers/net/ethernet/marvell/mvneta.c +++ b/drivers/net/ethernet/marvell/mvneta.c @@ -216,9 +216,6 @@ #define MVNETA_RX_COAL_PKTS 32 #define MVNETA_RX_COAL_USEC 100 -/* Timer */ -#define MVNETA_TX_DONE_TIMER_PERIOD 10 - /* Napi polling weight */ #define MVNETA_RX_POLL_WEIGHT 64 @@ -272,16 +269,11 @@ struct mvneta_port { void __iomem *base; struct mvneta_rx_queue *rxqs; struct mvneta_tx_queue *txqs; - struct timer_list tx_done_timer; struct net_device *dev; u32 cause_rx_tx; struct napi_struct napi; - /* Flags */ - unsigned long flags; -#define MVNETA_F_TX_DONE_TIMER_BIT 0 - /* Napi weight */ int weight; @@ -1140,17 +1132,6 @@ static void mvneta_tx_done_pkts_coal_set(struct mvneta_port *pp, txq->done_pkts_coal = value; } -/* Trigger tx done timer in MVNETA_TX_DONE_TIMER_PERIOD msecs */ -static void mvneta_add_tx_done_timer(struct mvneta_port *pp) -{ - if (test_and_set_bit(MVNETA_F_TX_DONE_TIMER_BIT, &pp->flags) == 0) { - pp->tx_done_timer.expires = jiffies + - msecs_to_jiffies(MVNETA_TX_DONE_TIMER_PERIOD); - add_timer(&pp->tx_done_timer); - } -} - - /* Handle rx descriptor fill by setting buf_cookie and buf_phys_addr */ static void mvneta_rx_desc_fill(struct mvneta_rx_desc *rx_desc, u32 phys_addr, u32 cookie) @@ -1632,15 +1613,6 @@ out: dev_kfree_skb_any(skb); } - if (txq->count >= MVNETA_TXDONE_COAL_PKTS) - mvneta_txq_done(pp, txq); - - /* If after calling mvneta_txq_done, count equals - * frags, we need to set the timer - */ - if (txq->count == frags && frags > 0) - mvneta_add_tx_done_timer(pp); - return NETDEV_TX_OK; } @@ -1916,14 +1888,22 @@ static int mvneta_poll(struct napi_struct *napi, int budget) /* Read cause register */ cause_rx_tx = mvreg_read(pp, MVNETA_INTR_NEW_CAUSE) & - MVNETA_RX_INTR_MASK(rxq_number); + (MVNETA_RX_INTR_MASK(rxq_number) | MVNETA_TX_INTR_MASK(txq_number)); + + /* Release Tx descriptors */ + if (cause_rx_tx & MVNETA_TX_INTR_MASK_ALL) { + int tx_todo = 0; + + mvneta_tx_done_gbe(pp, (cause_rx_tx & MVNETA_TX_INTR_MASK_ALL), &tx_todo); + cause_rx_tx &= ~MVNETA_TX_INTR_MASK_ALL; + } /* For the case where the last mvneta_poll did not process all * RX packets */ cause_rx_tx |= pp->cause_rx_tx; if (rxq_number > 1) { - while ((cause_rx_tx != 0) && (budget > 0)) { + while ((cause_rx_tx & MVNETA_RX_INTR_MASK_ALL) && (budget > 0)) { int count; struct mvneta_rx_queue *rxq; /* get rx queue number from cause_rx_tx */ @@ -1955,7 +1935,7 @@ static int mvneta_poll(struct napi_struct *napi, int budget) napi_complete(napi); local_irq_save(flags); mvreg_write(pp, MVNETA_INTR_NEW_MASK, - MVNETA_RX_INTR_MASK(rxq_number)); + MVNETA_RX_INTR_MASK(rxq_number) | MVNETA_TX_INTR_MASK(txq_number)); local_irq_restore(flags); } @@ -1963,26 +1943,6 @@ static int mvneta_poll(struct napi_struct *napi, int budget) return rx_done; } -/* tx done timer callback */ -static void mvneta_tx_done_timer_callback(unsigned long data) -{ - struct net_device *dev = (struct net_device *)data; - struct mvneta_port *pp = netdev_priv(dev); - int tx_done = 0, tx_todo = 0; - - if (!netif_running(dev)) - return ; - - clear_bit(MVNETA_F_TX_DONE_TIMER_BIT, &pp->flags); - - tx_done = mvneta_tx_done_gbe(pp, - (((1 << txq_number) - 1) & - MVNETA_CAUSE_TXQ_SENT_DESC_ALL_MASK), - &tx_todo); - if (tx_todo > 0) - mvneta_add_tx_done_timer(pp); -} - /* Handle rxq fill: allocates rxq skbs; called when initializing a port */ static int mvneta_rxq_fill(struct mvneta_port *pp, struct mvneta_rx_queue *rxq, int num) @@ -2232,7 +2192,7 @@ static void mvneta_start_dev(struct mvneta_port *pp) /* Unmask interrupts */ mvreg_write(pp, MVNETA_INTR_NEW_MASK, - MVNETA_RX_INTR_MASK(rxq_number)); + MVNETA_RX_INTR_MASK(rxq_number) | MVNETA_TX_INTR_MASK(txq_number)); phy_start(pp->phy_dev); netif_tx_start_all_queues(pp->dev); @@ -2518,8 +2478,6 @@ static int mvneta_stop(struct net_device *dev) free_irq(dev->irq, pp); mvneta_cleanup_rxqs(pp); mvneta_cleanup_txqs(pp); - del_timer(&pp->tx_done_timer); - clear_bit(MVNETA_F_TX_DONE_TIMER_BIT, &pp->flags); return 0; } @@ -2868,11 +2826,6 @@ static int mvneta_probe(struct platform_device *pdev) } } - pp->tx_done_timer.data = (unsigned long)dev; - pp->tx_done_timer.function = mvneta_tx_done_timer_callback; - init_timer(&pp->tx_done_timer); - clear_bit(MVNETA_F_TX_DONE_TIMER_BIT, &pp->flags); - pp->tx_ring_size = MVNETA_MAX_TXD; pp->rx_ring_size = MVNETA_MAX_RXD; -- 1.7.12.1