[PATCH net-next v2] r8152: divide the tx and rx bottom functions

From: Hayes Wang
Date: Mon Aug 19 2019 - 02:41:02 EST


Move the tx bottom function from NAPI to a new tasklet. Then, for
multi-cores, the bottom functions of tx and rx may be run at same
time with different cores. This is used to improve performance.

On x86, Tx/Rx 943/943 Mbits/sec -> 945/944.
For arm platform, Tx/Rx: 917/917 Mbits/sec -> 933/933.

Signed-off-by: Hayes Wang <hayeswang@xxxxxxxxxxx>
---
v2: add the performance number in the commit message.
---
drivers/net/usb/r8152.c | 39 ++++++++++++++++++++++++++-------------
1 file changed, 26 insertions(+), 13 deletions(-)

diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
index 40d18e866269..3ed9f8e082c9 100644
--- a/drivers/net/usb/r8152.c
+++ b/drivers/net/usb/r8152.c
@@ -619,7 +619,7 @@ enum rtl8152_flags {
RTL8152_LINK_CHG,
SELECTIVE_SUSPEND,
PHY_RESET,
- SCHEDULE_NAPI,
+ SCHEDULE_TASKLET,
GREEN_ETHERNET,
DELL_TB_RX_AGG_BUG,
};
@@ -733,6 +733,7 @@ struct r8152 {
#ifdef CONFIG_PM_SLEEP
struct notifier_block pm_notifier;
#endif
+ struct tasklet_struct tx_tl;

struct rtl_ops {
void (*init)(struct r8152 *);
@@ -1401,7 +1402,7 @@ static void write_bulk_callback(struct urb *urb)
return;

if (!skb_queue_empty(&tp->tx_queue))
- napi_schedule(&tp->napi);
+ tasklet_schedule(&tp->tx_tl);
}

static void intr_callback(struct urb *urb)
@@ -2179,8 +2180,12 @@ static void tx_bottom(struct r8152 *tp)
} while (res == 0);
}

-static void bottom_half(struct r8152 *tp)
+static void bottom_half(unsigned long data)
{
+ struct r8152 *tp;
+
+ tp = (struct r8152 *)data;
+
if (test_bit(RTL8152_UNPLUG, &tp->flags))
return;

@@ -2192,7 +2197,7 @@ static void bottom_half(struct r8152 *tp)
if (!netif_carrier_ok(tp->netdev))
return;

- clear_bit(SCHEDULE_NAPI, &tp->flags);
+ clear_bit(SCHEDULE_TASKLET, &tp->flags);

tx_bottom(tp);
}
@@ -2203,16 +2208,12 @@ static int r8152_poll(struct napi_struct *napi, int budget)
int work_done;

work_done = rx_bottom(tp, budget);
- bottom_half(tp);

if (work_done < budget) {
if (!napi_complete_done(napi, work_done))
goto out;
if (!list_empty(&tp->rx_done))
napi_schedule(napi);
- else if (!skb_queue_empty(&tp->tx_queue) &&
- !list_empty(&tp->tx_free))
- napi_schedule(napi);
}

out:
@@ -2366,11 +2367,11 @@ static netdev_tx_t rtl8152_start_xmit(struct sk_buff *skb,

if (!list_empty(&tp->tx_free)) {
if (test_bit(SELECTIVE_SUSPEND, &tp->flags)) {
- set_bit(SCHEDULE_NAPI, &tp->flags);
+ set_bit(SCHEDULE_TASKLET, &tp->flags);
schedule_delayed_work(&tp->schedule, 0);
} else {
usb_mark_last_busy(tp->udev);
- napi_schedule(&tp->napi);
+ tasklet_schedule(&tp->tx_tl);
}
} else if (skb_queue_len(&tp->tx_queue) > tp->tx_qlen) {
netif_stop_queue(netdev);
@@ -4020,9 +4021,11 @@ static void set_carrier(struct r8152 *tp)
} else {
if (netif_carrier_ok(netdev)) {
netif_carrier_off(netdev);
+ tasklet_disable(&tp->tx_tl);
napi_disable(napi);
tp->rtl_ops.disable(tp);
napi_enable(napi);
+ tasklet_enable(&tp->tx_tl);
netif_info(tp, link, netdev, "carrier off\n");
}
}
@@ -4055,10 +4058,10 @@ static void rtl_work_func_t(struct work_struct *work)
if (test_and_clear_bit(RTL8152_SET_RX_MODE, &tp->flags))
_rtl8152_set_rx_mode(tp->netdev);

- /* don't schedule napi before linking */
- if (test_and_clear_bit(SCHEDULE_NAPI, &tp->flags) &&
+ /* don't schedule tasket before linking */
+ if (test_and_clear_bit(SCHEDULE_TASKLET, &tp->flags) &&
netif_carrier_ok(tp->netdev))
- napi_schedule(&tp->napi);
+ tasklet_schedule(&tp->tx_tl);

mutex_unlock(&tp->control);

@@ -4144,6 +4147,7 @@ static int rtl8152_open(struct net_device *netdev)
goto out_unlock;
}
napi_enable(&tp->napi);
+ tasklet_enable(&tp->tx_tl);

mutex_unlock(&tp->control);

@@ -4171,6 +4175,7 @@ static int rtl8152_close(struct net_device *netdev)
#ifdef CONFIG_PM_SLEEP
unregister_pm_notifier(&tp->pm_notifier);
#endif
+ tasklet_disable(&tp->tx_tl);
if (!test_bit(RTL8152_UNPLUG, &tp->flags))
napi_disable(&tp->napi);
clear_bit(WORK_ENABLE, &tp->flags);
@@ -4440,6 +4445,7 @@ static int rtl8152_pre_reset(struct usb_interface *intf)
return 0;

netif_stop_queue(netdev);
+ tasklet_disable(&tp->tx_tl);
napi_disable(&tp->napi);
clear_bit(WORK_ENABLE, &tp->flags);
usb_kill_urb(tp->intr_urb);
@@ -4483,6 +4489,7 @@ static int rtl8152_post_reset(struct usb_interface *intf)
}

napi_enable(&tp->napi);
+ tasklet_enable(&tp->tx_tl);
netif_wake_queue(netdev);
usb_submit_urb(tp->intr_urb, GFP_KERNEL);

@@ -4636,10 +4643,12 @@ static int rtl8152_system_suspend(struct r8152 *tp)

clear_bit(WORK_ENABLE, &tp->flags);
usb_kill_urb(tp->intr_urb);
+ tasklet_disable(&tp->tx_tl);
napi_disable(napi);
cancel_delayed_work_sync(&tp->schedule);
tp->rtl_ops.down(tp);
napi_enable(napi);
+ tasklet_enable(&tp->tx_tl);
}

return 0;
@@ -5499,6 +5508,8 @@ static int rtl8152_probe(struct usb_interface *intf,
mutex_init(&tp->control);
INIT_DELAYED_WORK(&tp->schedule, rtl_work_func_t);
INIT_DELAYED_WORK(&tp->hw_phy_work, rtl_hw_phy_work_func_t);
+ tasklet_init(&tp->tx_tl, bottom_half, (unsigned long)tp);
+ tasklet_disable(&tp->tx_tl);

netdev->netdev_ops = &rtl8152_netdev_ops;
netdev->watchdog_timeo = RTL8152_TX_TIMEOUT;
@@ -5585,6 +5596,7 @@ static int rtl8152_probe(struct usb_interface *intf,

out1:
netif_napi_del(&tp->napi);
+ tasklet_kill(&tp->tx_tl);
usb_set_intfdata(intf, NULL);
out:
free_netdev(netdev);
@@ -5601,6 +5613,7 @@ static void rtl8152_disconnect(struct usb_interface *intf)

netif_napi_del(&tp->napi);
unregister_netdev(tp->netdev);
+ tasklet_kill(&tp->tx_tl);
cancel_delayed_work_sync(&tp->hw_phy_work);
tp->rtl_ops.unload(tp);
free_netdev(tp->netdev);
--
2.21.0