负载过大时，e1000_watchdog 反复 UP、DOWN 的问题 - Chinaunix

static void
e1000_watchdog(unsigned long data)
{
struct e1000_adapter *adapter = (struct e1000_adapter *) data;
struct net_device *netdev = adapter->;netdev;
struct e1000_desc_ring *txdr = &adapter->;tx_ring;
unsigned int i;
uint32_t link;
e1000_check_for_link(&adapter->;hw);
if((adapter->;hw.media_type == e1000_media_type_internal_serdes) &&
!(E1000_READ_REG(&adapter->;hw, TXCW) & E1000_TXCW_ANE))
link = !adapter->;hw.serdes_link_down;
else
link = E1000_READ_REG(&adapter->;hw, STATUS) & E1000_STATUS_LU;
if(link) {
if(!netif_carrier_ok(netdev)) {
e1000_get_speed_and_duplex(&adapter->;hw,
&adapter->;link_speed,
&adapter->;link_duplex);
DPRINTK(LINK, INFO, "NIC Link is Up %d Mbps %s\n",
adapter->;link_speed,
adapter->;link_duplex == FULL_DUPLEX ?
"Full Duplex" : "Half Duplex");
netif_carrier_on(netdev);
netif_wake_queue(netdev);
mod_timer(&adapter->;phy_info_timer, jiffies + 2 * HZ);
adapter->;smartspeed = 0;
}
} else {
if(netif_carrier_ok(netdev)) {
adapter->;link_speed = 0;
adapter->;link_duplex = 0;
DPRINTK(LINK, INFO, "NIC Link is Down\n");
netif_carrier_off(netdev);
netif_stop_queue(netdev);
mod_timer(&adapter->;phy_info_timer, jiffies + 2 * HZ);
}
e1000_smartspeed(adapter);
}
e1000_update_stats(adapter);
adapter->;hw.tx_packet_delta = adapter->;stats.tpt - adapter->;tpt_old;
adapter->;tpt_old = adapter->;stats.tpt;
adapter->;hw.collision_delta = adapter->;stats.colc - adapter->;colc_old;
adapter->;colc_old = adapter->;stats.colc;
adapter->;gorcl = adapter->;stats.gorcl - adapter->;gorcl_old;
adapter->;gorcl_old = adapter->;stats.gorcl;
adapter->;gotcl = adapter->;stats.gotcl - adapter->;gotcl_old;
adapter->;gotcl_old = adapter->;stats.gotcl;
e1000_update_adaptive(&adapter->;hw);
if(!netif_carrier_ok(netdev)) {
if(E1000_DESC_UNUSED(txdr) + 1 < txdr->;count) {
/* We've lost link, so the controller stops DMA,
* but we've got queued Tx work that's never going
* to get done, so reset controller to flush Tx.
* (Do the reset outside of interrupt context). */
schedule_work(&adapter->;tx_timeout_task);
}
}
/* Dynamic mode for Interrupt Throttle Rate (ITR) */
if(adapter->;hw.mac_type >;= e1000_82540 && adapter->;itr == 1) {
/* Symmetric Tx/Rx gets a reduced ITR=2000; Total
* asymmetrical Tx or Rx gets ITR=8000; everyone
* else is between 2000-8000. */
uint32_t goc = (adapter->;gotcl + adapter->;gorcl) / 10000;
uint32_t dif = (adapter->;gotcl >; adapter->;gorcl ?
adapter->;gotcl - adapter->;gorcl :
adapter->;gorcl - adapter->;gotcl) / 10000;
uint32_t itr = goc >; 0 ? (dif * 6000 / goc + 2000) : 8000;
E1000_WRITE_REG(&adapter->;hw, ITR, 1000000000 / (itr * 256));
}
/* Cause software interrupt to ensure rx ring is cleaned */
E1000_WRITE_REG(&adapter->;hw, ICS, E1000_ICS_RXDMT0);
/* Early detection of hung controller */
i = txdr->;next_to_clean;
if(txdr->;buffer_info[i].dma &&
time_after(jiffies, txdr->;buffer_info[i].time_stamp + HZ) &&
!(E1000_READ_REG(&adapter->;hw, STATUS) & E1000_STATUS_TXOFF))
netif_stop_queue(netdev);
/* Reset the timer */
mod_timer(&adapter->;watchdog_timer, jiffies + 2 * HZ);
}

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This value delays the generation of receive interrupts in units of 1.024 microseconds. Receive interrupt reduction can improve CPU efficiency if properly tuned for specific network traffic. Increasing this value adds extra latency to frame reception and can end up decreasing the throughput of TCP traffic. If the system is reporting dropped receives, this value may be set too high, causing the driver to run out of available receive descriptors.
CAUTION: When setting RxIntDelay to a value other than 0, adapters may hang (stop transmitting) under certain network conditions. If this occurs a NETDEV WATCHDOG message is logged in the system event log. In addition, the controller is automatically reset, restoring the network connection. To eliminate the potential for the hang ensure that RxIntDelay is set to zero.