i40e: Add a SW workaround for lost interrupts
This patch adds a workaround for cases where we might have
interrupts that got lost but WB happened.
If that happens without this patch we will see a tx_timeout.
To work around it, this patch goes ahead and reschedules NAPI
in that situation, if NAPI is not already scheduled.
We also add a counter in ethtool to keep track of when
we detect a case of tx_lost_interrupt.
Note: napi_reschedule() can be safely called from process/service_task
context and is done in other drivers as well without an issue.
Change-ID: I00f98f1ce3774524d9421227652bef20fcbd0d20
Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index 161603b..aa1c7ca 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -819,6 +819,7 @@
struct i40e_eth_stats *oes;
struct i40e_eth_stats *es; /* device's eth stats */
u32 tx_restart, tx_busy;
+ u64 tx_lost_interrupt;
struct i40e_ring *p;
u32 rx_page, rx_buf;
u64 bytes, packets;
@@ -844,6 +845,7 @@
rx_b = rx_p = 0;
tx_b = tx_p = 0;
tx_restart = tx_busy = tx_linearize = tx_force_wb = 0;
+ tx_lost_interrupt = 0;
rx_page = 0;
rx_buf = 0;
rcu_read_lock();
@@ -862,6 +864,7 @@
tx_busy += p->tx_stats.tx_busy;
tx_linearize += p->tx_stats.tx_linearize;
tx_force_wb += p->tx_stats.tx_force_wb;
+ tx_lost_interrupt += p->tx_stats.tx_lost_interrupt;
/* Rx queue is part of the same block as Tx queue */
p = &p[1];
@@ -880,6 +883,7 @@
vsi->tx_busy = tx_busy;
vsi->tx_linearize = tx_linearize;
vsi->tx_force_wb = tx_force_wb;
+ vsi->tx_lost_interrupt = tx_lost_interrupt;
vsi->rx_page_failed = rx_page;
vsi->rx_buf_failed = rx_buf;
@@ -4349,7 +4353,7 @@
{
struct i40e_ring *tx_ring = NULL;
struct i40e_pf *pf;
- u32 head, val, tx_pending;
+ u32 head, val, tx_pending_hw;
int i;
pf = vsi->back;
@@ -4375,16 +4379,9 @@
else
val = rd32(&pf->hw, I40E_PFINT_DYN_CTL0);
- /* Bail out if interrupts are disabled because napi_poll
- * execution in-progress or will get scheduled soon.
- * napi_poll cleans TX and RX queues and updates 'next_to_clean'.
- */
- if (!(val & I40E_PFINT_DYN_CTLN_INTENA_MASK))
- return;
-
head = i40e_get_head(tx_ring);
- tx_pending = i40e_get_tx_pending(tx_ring);
+ tx_pending_hw = i40e_get_tx_pending(tx_ring, false);
/* HW is done executing descriptors, updated HEAD write back,
* but SW hasn't processed those descriptors. If interrupt is
@@ -4392,12 +4389,12 @@
* dev_watchdog detecting timeout on those netdev_queue,
* hence proactively trigger SW interrupt.
*/
- if (tx_pending) {
+ if (tx_pending_hw && (!(val & I40E_PFINT_DYN_CTLN_INTENA_MASK))) {
/* NAPI Poll didn't run and clear since it was set */
if (test_and_clear_bit(I40E_Q_VECTOR_HUNG_DETECT,
&tx_ring->q_vector->hung_detected)) {
- netdev_info(vsi->netdev, "VSI_seid %d, Hung TX queue %d, tx_pending: %d, NTC:0x%x, HWB: 0x%x, NTU: 0x%x, TAIL: 0x%x\n",
- vsi->seid, q_idx, tx_pending,
+ netdev_info(vsi->netdev, "VSI_seid %d, Hung TX queue %d, tx_pending_hw: %d, NTC:0x%x, HWB: 0x%x, NTU: 0x%x, TAIL: 0x%x\n",
+ vsi->seid, q_idx, tx_pending_hw,
tx_ring->next_to_clean, head,
tx_ring->next_to_use,
readl(tx_ring->tail));
@@ -4410,6 +4407,17 @@
&tx_ring->q_vector->hung_detected);
}
}
+
+ /* This is the case where we have interrupts missing,
+ * so the tx_pending in HW will most likely be 0, but we
+ * will have tx_pending in SW since the WB happened but the
+ * interrupt got lost.
+ */
+ if ((!tx_pending_hw) && i40e_get_tx_pending(tx_ring, true) &&
+ (!(val & I40E_PFINT_DYN_CTLN_INTENA_MASK))) {
+ if (napi_reschedule(&tx_ring->q_vector->napi))
+ tx_ring->tx_stats.tx_lost_interrupt++;
+ }
}
/**