From dd353109e41c1e92e0cea9954404a6f5a7d46218 Mon Sep 17 00:00:00 2001 From: Anjali Singhai Jain Date: Fri, 15 Jan 2016 14:33:12 -0800 Subject: [PATCH] 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 Tested-by: Andrew Bowers Signed-off-by: Jeff Kirsher --- drivers/net/ethernet/intel/i40e/i40e.h | 1 + .../net/ethernet/intel/i40e/i40e_ethtool.c | 1 + drivers/net/ethernet/intel/i40e/i40e_main.c | 32 ++++++++++++------- drivers/net/ethernet/intel/i40e/i40e_txrx.c | 10 ++++-- drivers/net/ethernet/intel/i40e/i40e_txrx.h | 3 +- drivers/net/ethernet/intel/i40evf/i40e_txrx.c | 10 ++++-- drivers/net/ethernet/intel/i40evf/i40e_txrx.h | 3 +- 7 files changed, 40 insertions(+), 20 deletions(-) diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h index 5ea431d04e8c..5d8e159e18d7 100644 --- a/drivers/net/ethernet/intel/i40e/i40e.h +++ b/drivers/net/ethernet/intel/i40e/i40e.h @@ -512,6 +512,7 @@ struct i40e_vsi { u32 tx_busy; u64 tx_linearize; u64 tx_force_wb; + u64 tx_lost_interrupt; u32 rx_buf_failed; u32 rx_page_failed; diff --git a/drivers/net/ethernet/intel/i40e/i40e_ethtool.c b/drivers/net/ethernet/intel/i40e/i40e_ethtool.c index 230fa402d2da..5778f9e2f43c 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_ethtool.c +++ b/drivers/net/ethernet/intel/i40e/i40e_ethtool.c @@ -89,6 +89,7 @@ static const struct i40e_stats i40e_gstrings_misc_stats[] = { I40E_VSI_STAT("rx_unknown_protocol", eth_stats.rx_unknown_protocol), I40E_VSI_STAT("tx_linearize", tx_linearize), I40E_VSI_STAT("tx_force_wb", tx_force_wb), + I40E_VSI_STAT("tx_lost_interrupt", tx_lost_interrupt), I40E_VSI_STAT("rx_alloc_fail", rx_buf_failed), I40E_VSI_STAT("rx_pg_alloc_fail", rx_page_failed), }; diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c index 161603b930c9..aa1c7ca59d53 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_main.c +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c @@ -819,6 +819,7 @@ static void i40e_update_vsi_stats(struct i40e_vsi *vsi) 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 @@ static void i40e_update_vsi_stats(struct i40e_vsi *vsi) 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 @@ static void i40e_update_vsi_stats(struct i40e_vsi *vsi) 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 @@ static void i40e_update_vsi_stats(struct i40e_vsi *vsi) 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 @@ static void i40e_detect_recover_hung_queue(int q_idx, struct i40e_vsi *vsi) { 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 @@ static void i40e_detect_recover_hung_queue(int q_idx, struct i40e_vsi *vsi) 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 @@ static void i40e_detect_recover_hung_queue(int q_idx, struct i40e_vsi *vsi) * 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 @@ static void i40e_detect_recover_hung_queue(int q_idx, struct i40e_vsi *vsi) &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++; + } } /** diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c index 0ffa9a89986c..5b43585704fe 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c @@ -610,15 +610,19 @@ void i40e_free_tx_resources(struct i40e_ring *tx_ring) /** * i40e_get_tx_pending - how many tx descriptors not processed * @tx_ring: the ring of descriptors + * @in_sw: is tx_pending being checked in SW or HW * * Since there is no access to the ring head register * in XL710, we need to use our local copies **/ -u32 i40e_get_tx_pending(struct i40e_ring *ring) +u32 i40e_get_tx_pending(struct i40e_ring *ring, bool in_sw) { u32 head, tail; - head = i40e_get_head(ring); + if (!in_sw) + head = i40e_get_head(ring); + else + head = ring->next_to_clean; tail = readl(ring->tail); if (head != tail) @@ -741,7 +745,7 @@ static bool i40e_clean_tx_irq(struct i40e_ring *tx_ring, int budget) * them to be written back in case we stay in NAPI. * In this mode on X722 we do not enable Interrupt. */ - j = i40e_get_tx_pending(tx_ring); + j = i40e_get_tx_pending(tx_ring, false); if (budget && ((j / (WB_STRIDE + 1)) == 0) && (j != 0) && diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.h b/drivers/net/ethernet/intel/i40e/i40e_txrx.h index ae22c4e9162f..3acc9244134d 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.h +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.h @@ -203,6 +203,7 @@ struct i40e_tx_queue_stats { u64 tx_done_old; u64 tx_linearize; u64 tx_force_wb; + u64 tx_lost_interrupt; }; struct i40e_rx_queue_stats { @@ -338,7 +339,7 @@ int i40e_tx_prepare_vlan_flags(struct sk_buff *skb, struct i40e_ring *tx_ring, u32 *flags); #endif void i40e_force_wb(struct i40e_vsi *vsi, struct i40e_q_vector *q_vector); -u32 i40e_get_tx_pending(struct i40e_ring *ring); +u32 i40e_get_tx_pending(struct i40e_ring *ring, bool in_sw); /** * i40e_get_head - Retrieve head from head writeback diff --git a/drivers/net/ethernet/intel/i40evf/i40e_txrx.c b/drivers/net/ethernet/intel/i40evf/i40e_txrx.c index 76bad75b0f67..0f73a4f2e9ed 100644 --- a/drivers/net/ethernet/intel/i40evf/i40e_txrx.c +++ b/drivers/net/ethernet/intel/i40evf/i40e_txrx.c @@ -129,15 +129,19 @@ void i40evf_free_tx_resources(struct i40e_ring *tx_ring) /** * i40evf_get_tx_pending - how many Tx descriptors not processed * @tx_ring: the ring of descriptors + * @in_sw: is tx_pending being checked in SW or HW * * Since there is no access to the ring head register * in XL710, we need to use our local copies **/ -u32 i40evf_get_tx_pending(struct i40e_ring *ring) +u32 i40evf_get_tx_pending(struct i40e_ring *ring, bool in_sw) { u32 head, tail; - head = i40e_get_head(ring); + if (!in_sw) + head = i40e_get_head(ring); + else + head = ring->next_to_clean; tail = readl(ring->tail); if (head != tail) @@ -259,7 +263,7 @@ static bool i40e_clean_tx_irq(struct i40e_ring *tx_ring, int budget) * them to be written back in case we stay in NAPI. * In this mode on X722 we do not enable Interrupt. */ - j = i40evf_get_tx_pending(tx_ring); + j = i40evf_get_tx_pending(tx_ring, false); if (budget && ((j / (WB_STRIDE + 1)) == 0) && (j > 0) && diff --git a/drivers/net/ethernet/intel/i40evf/i40e_txrx.h b/drivers/net/ethernet/intel/i40evf/i40e_txrx.h index 5467fcdf7670..81c96619287b 100644 --- a/drivers/net/ethernet/intel/i40evf/i40e_txrx.h +++ b/drivers/net/ethernet/intel/i40evf/i40e_txrx.h @@ -202,6 +202,7 @@ struct i40e_tx_queue_stats { u64 tx_done_old; u64 tx_linearize; u64 tx_force_wb; + u64 tx_lost_interrupt; }; struct i40e_rx_queue_stats { @@ -326,7 +327,7 @@ void i40evf_free_tx_resources(struct i40e_ring *tx_ring); void i40evf_free_rx_resources(struct i40e_ring *rx_ring); int i40evf_napi_poll(struct napi_struct *napi, int budget); void i40evf_force_wb(struct i40e_vsi *vsi, struct i40e_q_vector *q_vector); -u32 i40evf_get_tx_pending(struct i40e_ring *ring); +u32 i40evf_get_tx_pending(struct i40e_ring *ring, bool in_sw); /** * i40e_get_head - Retrieve head from head writeback -- 2.20.1