| Message ID | 20201120150208.6838-1-vincent.whitchurch@axis.com |
|---|---|
| State | New |
| Headers | show |
| Series | [net] net: stmmac: Use hrtimer for TX coalescing | expand |
On Fri, 20 Nov 2020 16:02:08 +0100 Vincent Whitchurch wrote: > 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 <vincent.whitchurch@axis.com> Looks perfectly reasonable, but you marked it for net. Do you consider this to be a bug fix, and need it backported to stable? Otherwise I'd rather apply it to net-next.
On Tue, Nov 24, 2020 at 01:46:00AM +0100, Jakub Kicinski wrote: > On Fri, 20 Nov 2020 16:02:08 +0100 Vincent Whitchurch wrote: > > 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 <vincent.whitchurch@axis.com> > > Looks perfectly reasonable, but you marked it for net. Do you consider > this to be a bug fix, and need it backported to stable? Otherwise I'd > rather apply it to net-next. No, sorry, I think a backport to stable is unnecessary. It should be fine to apply it to net-next. Thanks.
On Tue, 24 Nov 2020 05:11:27 +0100 Vincent Whitchurch wrote: > On Tue, Nov 24, 2020 at 01:46:00AM +0100, Jakub Kicinski wrote: > > On Fri, 20 Nov 2020 16:02:08 +0100 Vincent Whitchurch wrote: > > > 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 <vincent.whitchurch@axis.com> > > > > Looks perfectly reasonable, but you marked it for net. Do you consider > > this to be a bug fix, and need it backported to stable? Otherwise I'd > > rather apply it to net-next. > > No, sorry, I think a backport to stable is unnecessary. It should be > fine to apply it to net-next. Thanks. Applied to net-next, thank you!
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h index 727e68dfaf1c..04b7162211cb 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 <linux/clk.h> +#include <linux/hrtimer.h> #include <linux/if_vlan.h> #include <linux/stmmac.h> #include <linux/phylink.h> @@ -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 ba45fe237512..eea740c06f52 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. @@ -2051,7 +2051,8 @@ 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)); @@ -2335,7 +2336,8 @@ 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); } /** @@ -2344,9 +2346,9 @@ 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; @@ -2360,6 +2362,8 @@ static void stmmac_tx_timer(struct timer_list *t) spin_unlock_irqrestore(&ch->lock, flags); __napi_schedule(&ch->tx_napi); } + + return HRTIMER_NORESTART; } /** @@ -2382,7 +2386,8 @@ 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; } } @@ -2874,7 +2879,7 @@ static int stmmac_open(struct net_device *dev) 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: @@ -2907,7 +2912,7 @@ 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); @@ -5140,7 +5145,7 @@ 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);
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 <vincent.whitchurch@axis.com> --- drivers/net/ethernet/stmicro/stmmac/stmmac.h | 3 ++- .../net/ethernet/stmicro/stmmac/stmmac_main.c | 23 +++++++++++-------- 2 files changed, 16 insertions(+), 10 deletions(-)