From 8dcf2c212078d8ac0714ae872a5496a36eda21e6 Mon Sep 17 00:00:00 2001 From: Kurt Kanzenbach Date: Fri, 21 Jun 2024 08:56:30 +0200 Subject: [PATCH] igc: Get rid of spurious interrupts When running the igc with XDP/ZC in busy polling mode with deferral of hard interrupts, interrupts still happen from time to time. That is caused by the igc task watchdog which triggers Rx interrupts periodically. That mechanism has been introduced to overcome skb/memory allocation failures [1]. So the Rx clean functions stop processing the Rx ring in case of such failure. The task watchdog triggers Rx interrupts periodically in the hope that memory became available in the mean time. The current behavior is undesirable for real time applications, because the driver induced Rx interrupts trigger also the softirq processing. However, all real time packets should be processed by the application which uses the busy polling method. Therefore, only trigger the Rx interrupts in case of real allocation failures. Introduce a new flag for signaling that condition. [1] - https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/?id=3be507547e6177e5c808544bd6a2efa2c7f1d436 Reviewed-by: Sebastian Andrzej Siewior Acked-by: Vinicius Costa Gomes Acked-by: Maciej Fijalkowski Signed-off-by: Kurt Kanzenbach Reviewed-by: Simon Horman Tested-by: Mor Bar-Gabay Signed-off-by: Tony Nguyen --- drivers/net/ethernet/intel/igc/igc.h | 1 + drivers/net/ethernet/intel/igc/igc_main.c | 30 ++++++++++++++++++++--- 2 files changed, 27 insertions(+), 4 deletions(-) diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h index 8642d67af6ccc..eac0f966e0e4c 100644 --- a/drivers/net/ethernet/intel/igc/igc.h +++ b/drivers/net/ethernet/intel/igc/igc.h @@ -687,6 +687,7 @@ enum igc_ring_flags_t { IGC_RING_FLAG_TX_DETECT_HANG, IGC_RING_FLAG_AF_XDP_ZC, IGC_RING_FLAG_TX_HWTSTAMP, + IGC_RING_FLAG_RX_ALLOC_FAILED, }; #define ring_uses_large_buffer(ring) \ diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c index 96b2f2a37bc3d..da322899e834c 100644 --- a/drivers/net/ethernet/intel/igc/igc_main.c +++ b/drivers/net/ethernet/intel/igc/igc_main.c @@ -2191,6 +2191,7 @@ static bool igc_alloc_mapped_page(struct igc_ring *rx_ring, page = dev_alloc_pages(igc_rx_pg_order(rx_ring)); if (unlikely(!page)) { rx_ring->rx_stats.alloc_failed++; + set_bit(IGC_RING_FLAG_RX_ALLOC_FAILED, &rx_ring->flags); return false; } @@ -2207,6 +2208,7 @@ static bool igc_alloc_mapped_page(struct igc_ring *rx_ring, __free_page(page); rx_ring->rx_stats.alloc_failed++; + set_bit(IGC_RING_FLAG_RX_ALLOC_FAILED, &rx_ring->flags); return false; } @@ -2658,6 +2660,7 @@ static int igc_clean_rx_irq(struct igc_q_vector *q_vector, const int budget) if (!skb) { rx_ring->rx_stats.alloc_failed++; rx_buffer->pagecnt_bias++; + set_bit(IGC_RING_FLAG_RX_ALLOC_FAILED, &rx_ring->flags); break; } @@ -2738,6 +2741,7 @@ static void igc_dispatch_skb_zc(struct igc_q_vector *q_vector, skb = igc_construct_skb_zc(ring, xdp); if (!skb) { ring->rx_stats.alloc_failed++; + set_bit(IGC_RING_FLAG_RX_ALLOC_FAILED, &ring->flags); return; } @@ -5807,11 +5811,29 @@ no_wait: if (adapter->flags & IGC_FLAG_HAS_MSIX) { u32 eics = 0; - for (i = 0; i < adapter->num_q_vectors; i++) - eics |= adapter->q_vector[i]->eims_value; - wr32(IGC_EICS, eics); + for (i = 0; i < adapter->num_q_vectors; i++) { + struct igc_q_vector *q_vector = adapter->q_vector[i]; + struct igc_ring *rx_ring; + + if (!q_vector->rx.ring) + continue; + + rx_ring = adapter->rx_ring[q_vector->rx.ring->queue_index]; + + if (test_bit(IGC_RING_FLAG_RX_ALLOC_FAILED, &rx_ring->flags)) { + eics |= q_vector->eims_value; + clear_bit(IGC_RING_FLAG_RX_ALLOC_FAILED, &rx_ring->flags); + } + } + if (eics) + wr32(IGC_EICS, eics); } else { - wr32(IGC_ICS, IGC_ICS_RXDMT0); + struct igc_ring *rx_ring = adapter->rx_ring[0]; + + if (test_bit(IGC_RING_FLAG_RX_ALLOC_FAILED, &rx_ring->flags)) { + clear_bit(IGC_RING_FLAG_RX_ALLOC_FAILED, &rx_ring->flags); + wr32(IGC_ICS, IGC_ICS_RXDMT0); + } } igc_ptp_tx_hang(adapter); -- 2.39.5