From d5a05e69ac6e4c431c380ced2b534c91f7bc3280 Mon Sep 17 00:00:00 2001 From: Vincent Whitchurch Date: Fri, 20 Nov 2020 16:02:08 +0100 Subject: [PATCH] net: stmmac: Use hrtimer for TX coalescing This driver uses a normal timer for TX coalescing, which means that the with the default tx-usecs of 1000 microseconds the cleanups actually happen 10 ms or more later with HZ=100. This leads to very low througput with TCP when bridged to a slow link such as a 4G modem. Fix this by using an hrtimer instead. On my ARM platform with HZ=100 and the default TX coalescing settings (tx-frames 25 tx-usecs 1000), with "tc qdisc add dev eth0 root netem delay 60ms 40ms rate 50Mbit" run on the server, netperf's TCP_STREAM improves from ~5.5 Mbps to ~100 Mbps. Signed-off-by: Vincent Whitchurch Link: https://lore.kernel.org/r/20201120150208.6838-1-vincent.whitchurch@axis.com Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/stmicro/stmmac/stmmac.h | 3 ++- drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 23 ++++++++++++++--------- 2 files changed, 16 insertions(+), 10 deletions(-) diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h index c88ee8e..e553b9a 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h @@ -13,6 +13,7 @@ #define DRV_MODULE_VERSION "Jan_2016" #include +#include #include #include #include @@ -46,7 +47,7 @@ struct stmmac_tx_info { struct stmmac_tx_queue { u32 tx_count_frames; int tbs; - struct timer_list txtimer; + struct hrtimer txtimer; u32 queue_index; struct stmmac_priv *priv_data; struct dma_extended_desc *dma_etx ____cacheline_aligned_in_smp; diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index c8770e9..8c1ac75 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -111,7 +111,7 @@ static void stmmac_init_fs(struct net_device *dev); static void stmmac_exit_fs(struct net_device *dev); #endif -#define STMMAC_COAL_TIMER(x) (jiffies + usecs_to_jiffies(x)) +#define STMMAC_COAL_TIMER(x) (ns_to_ktime((x) * NSEC_PER_USEC)) /** * stmmac_verify_args - verify the driver parameters. @@ -2076,7 +2076,8 @@ static int stmmac_tx_clean(struct stmmac_priv *priv, int budget, u32 queue) /* We still have pending packets, let's call for a new scheduling */ if (tx_q->dirty_tx != tx_q->cur_tx) - mod_timer(&tx_q->txtimer, STMMAC_COAL_TIMER(priv->tx_coal_timer)); + hrtimer_start(&tx_q->txtimer, STMMAC_COAL_TIMER(priv->tx_coal_timer), + HRTIMER_MODE_REL); __netif_tx_unlock_bh(netdev_get_tx_queue(priv->dev, queue)); @@ -2360,7 +2361,8 @@ static void stmmac_tx_timer_arm(struct stmmac_priv *priv, u32 queue) { struct stmmac_tx_queue *tx_q = &priv->tx_queue[queue]; - mod_timer(&tx_q->txtimer, STMMAC_COAL_TIMER(priv->tx_coal_timer)); + hrtimer_start(&tx_q->txtimer, STMMAC_COAL_TIMER(priv->tx_coal_timer), + HRTIMER_MODE_REL); } /** @@ -2369,9 +2371,9 @@ static void stmmac_tx_timer_arm(struct stmmac_priv *priv, u32 queue) * Description: * This is the timer handler to directly invoke the stmmac_tx_clean. */ -static void stmmac_tx_timer(struct timer_list *t) +static enum hrtimer_restart stmmac_tx_timer(struct hrtimer *t) { - struct stmmac_tx_queue *tx_q = from_timer(tx_q, t, txtimer); + struct stmmac_tx_queue *tx_q = container_of(t, struct stmmac_tx_queue, txtimer); struct stmmac_priv *priv = tx_q->priv_data; struct stmmac_channel *ch; @@ -2385,6 +2387,8 @@ static void stmmac_tx_timer(struct timer_list *t) spin_unlock_irqrestore(&ch->lock, flags); __napi_schedule(&ch->tx_napi); } + + return HRTIMER_NORESTART; } /** @@ -2407,7 +2411,8 @@ static void stmmac_init_coalesce(struct stmmac_priv *priv) for (chan = 0; chan < tx_channel_count; chan++) { struct stmmac_tx_queue *tx_q = &priv->tx_queue[chan]; - timer_setup(&tx_q->txtimer, stmmac_tx_timer, 0); + hrtimer_init(&tx_q->txtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); + tx_q->txtimer.function = stmmac_tx_timer; } } @@ -2899,7 +2904,7 @@ irq_error: phylink_stop(priv->phylink); for (chan = 0; chan < priv->plat->tx_queues_to_use; chan++) - del_timer_sync(&priv->tx_queue[chan].txtimer); + hrtimer_cancel(&priv->tx_queue[chan].txtimer); stmmac_hw_teardown(dev); init_error: @@ -2932,7 +2937,7 @@ static int stmmac_release(struct net_device *dev) stmmac_disable_all_queues(priv); for (chan = 0; chan < priv->plat->tx_queues_to_use; chan++) - del_timer_sync(&priv->tx_queue[chan].txtimer); + hrtimer_cancel(&priv->tx_queue[chan].txtimer); /* Free the IRQ lines */ free_irq(dev->irq, dev); @@ -5165,7 +5170,7 @@ int stmmac_suspend(struct device *dev) stmmac_disable_all_queues(priv); for (chan = 0; chan < priv->plat->tx_queues_to_use; chan++) - del_timer_sync(&priv->tx_queue[chan].txtimer); + hrtimer_cancel(&priv->tx_queue[chan].txtimer); /* Stop TX/RX DMA */ stmmac_stop_all_dma(priv); -- 2.7.4