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bh=D73eoZ+ww6rBa72YElmXEJrsMwkJILvJ3E1tcTzlOPg=; b=5ZviqxXM6cwlRUAog+MIbJm463ZHrTr/HS0phchzqQJVZW2/3I0ul5ppJkRUOoRYQtV4Rp SatC8K0n4KOrvwBw== X-Mailman-Original-Authentication-Results: smtp3.osuosl.org; dmarc=pass (p=none dis=none) header.from=linutronix.de X-Mailman-Original-Authentication-Results: smtp3.osuosl.org; dkim=pass (2048-bit key, unprotected) header.d=linutronix.de header.i=@linutronix.de header.a=rsa-sha256 header.s=2020 header.b=RK7Px/5z; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=ed25519-sha256 header.s=2020e header.b=5ZviqxXM Subject: [Intel-wired-lan] [PATCH iwl-next] igc: Get rid of spurious interrupts X-BeenThere: intel-wired-lan@osuosl.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Wired Ethernet Linux Kernel Driver Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Maciej Fijalkowski , Vinicius Costa Gomes , netdev@vger.kernel.org, Sebastian Andrzej Siewior , Kurt Kanzenbach , Eric Dumazet , intel-wired-lan@lists.osuosl.org, Jakub Kicinski , Paolo Abeni , "David S. Miller" Errors-To: intel-wired-lan-bounces@osuosl.org Sender: "Intel-wired-lan" 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 Signed-off-by: Kurt Kanzenbach Reviewed-by: Sebastian Andrzej Siewior Acked-by: Maciej Fijalkowski Acked-by: Vinicius Costa Gomes Acked-by: Vinicius Costa Gomes --- drivers/net/ethernet/intel/igc/igc.h | 1 + drivers/net/ethernet/intel/igc/igc_main.c | 24 ++++++++++++++++++++---- 2 files changed, 21 insertions(+), 4 deletions(-) --- base-commit: bb678f01804ccaa861b012b2b9426d69673d8a84 change-id: 20240611-igc_irq-ccc1c8bc6890 Best regards, diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h index 8b14c029eda1..7bfe5030e2c0 100644 --- a/drivers/net/ethernet/intel/igc/igc.h +++ b/drivers/net/ethernet/intel/igc/igc.h @@ -682,6 +682,7 @@ 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 305e05294a26..e666739dfac7 100644 --- a/drivers/net/ethernet/intel/igc/igc_main.c +++ b/drivers/net/ethernet/intel/igc/igc_main.c @@ -2192,6 +2192,7 @@ 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; } @@ -2208,6 +2209,7 @@ 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; } @@ -2659,6 +2661,7 @@ 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; } @@ -2739,6 +2742,7 @@ 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; } @@ -5811,11 +5815,23 @@ static void igc_watchdog_task(struct work_struct *work) 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_ring *rx_ring = adapter->rx_ring[i]; + + if (test_bit(IGC_RING_FLAG_RX_ALLOC_FAILED, &rx_ring->flags)) { + eics |= adapter->q_vector[i]->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);