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Message-ID: <20201120150208.6838-1-vincent.whitchurch@axis.com>
Date: Fri, 20 Nov 2020 16:02:08 +0100
From: Vincent Whitchurch <vincent.whitchurch@...s.com>
To: <peppe.cavallaro@...com>, <alexandre.torgue@...com>,
<joabreu@...opsys.com>, <davem@...emloft.net>, <kuba@...nel.org>
CC: <kernel@...s.com>, <netdev@...r.kernel.org>,
Vincent Whitchurch <vincent.whitchurch@...s.com>
Subject: [PATCH net] 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 <vincent.whitchurch@...s.com>
---
drivers/net/ethernet/stmicro/stmmac/stmmac.h | 3 ++-
.../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 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);
--
2.28.0
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