From e4ac382ebfb4e40dbf01db9ab4a42b10b298946a Mon Sep 17 00:00:00 2001 From: Shay Agroskin Date: Tue, 8 Jun 2021 19:01:09 +0300 Subject: [PATCH] net: ena: optimize data access in fast-path code This tweaks several small places to improve the data access in fast path: * Remove duplicates of first_interrupt flag and surround it with WRITE/READ_ONCE macros: The flag is used to detect HW disorders in its interrupt communication with the driver. The flag is set when an interrupt is received and used in the health check function (ena_timer_service()) to help it find irregularities. * Reorder some fields in ena_napi struct to take better advantage of cache access pattern. * Move XDP TX queue number to a variable to save its calculation for every packet. * Use likely in a condition to improve branch prediction The 'first_interrupt' and 'interrupt_masked' flags were moved to reside in the same cache line as the first fields of 'napi' struct. This placement ensures that all memory accessed during upper-half handler reside in the same cacheline (napi_schedule_irqoff() only accesses 'state' and 'poll_list' fields which are at the beginning of napi struct). Signed-off-by: Sameeh Jubran Signed-off-by: Shay Agroskin Signed-off-by: David S. Miller --- drivers/net/ethernet/amazon/ena/ena_eth_com.c | 2 +- drivers/net/ethernet/amazon/ena/ena_netdev.c | 23 +++++++++++------------ drivers/net/ethernet/amazon/ena/ena_netdev.h | 11 +++++++---- 3 files changed, 19 insertions(+), 17 deletions(-) diff --git a/drivers/net/ethernet/amazon/ena/ena_eth_com.c b/drivers/net/ethernet/amazon/ena/ena_eth_com.c index c3be751..2aecd4c 100644 --- a/drivers/net/ethernet/amazon/ena/ena_eth_com.c +++ b/drivers/net/ethernet/amazon/ena/ena_eth_com.c @@ -151,7 +151,7 @@ static int ena_com_close_bounce_buffer(struct ena_com_io_sq *io_sq) return 0; /* bounce buffer was used, so write it and get a new one */ - if (pkt_ctrl->idx) { + if (likely(pkt_ctrl->idx)) { rc = ena_com_write_bounce_buffer_to_dev(io_sq, pkt_ctrl->curr_bounce_buf); if (unlikely(rc)) diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c b/drivers/net/ethernet/amazon/ena/ena_netdev.c index 881f887..b613067 100644 --- a/drivers/net/ethernet/amazon/ena/ena_netdev.c +++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c @@ -197,7 +197,6 @@ static int ena_xdp_io_poll(struct napi_struct *napi, int budget) int ret; xdp_ring = ena_napi->xdp_ring; - xdp_ring->first_interrupt = ena_napi->first_interrupt; xdp_budget = budget; @@ -383,7 +382,6 @@ static int ena_xdp_execute(struct ena_ring *rx_ring, struct xdp_buff *xdp) u32 verdict = XDP_PASS; struct xdp_frame *xdpf; u64 *xdp_stat; - int qid; rcu_read_lock(); xdp_prog = READ_ONCE(rx_ring->xdp_bpf_prog); @@ -404,8 +402,7 @@ static int ena_xdp_execute(struct ena_ring *rx_ring, struct xdp_buff *xdp) } /* Find xmit queue */ - qid = rx_ring->qid + rx_ring->adapter->num_io_queues; - xdp_ring = &rx_ring->adapter->tx_ring[qid]; + xdp_ring = rx_ring->xdp_ring; /* The XDP queues are shared between XDP_TX and XDP_REDIRECT */ spin_lock(&xdp_ring->xdp_tx_lock); @@ -681,7 +678,6 @@ static void ena_init_io_rings_common(struct ena_adapter *adapter, ring->ena_dev = adapter->ena_dev; ring->per_napi_packets = 0; ring->cpu = 0; - ring->first_interrupt = false; ring->no_interrupt_event_cnt = 0; u64_stats_init(&ring->syncp); } @@ -725,6 +721,7 @@ static void ena_init_io_rings(struct ena_adapter *adapter, ena_com_get_nonadaptive_moderation_interval_rx(ena_dev); rxr->empty_rx_queue = 0; adapter->ena_napi[i].dim.mode = DIM_CQ_PERIOD_MODE_START_FROM_EQE; + rxr->xdp_ring = &adapter->tx_ring[i + adapter->num_io_queues]; } } } @@ -1922,9 +1919,6 @@ static int ena_io_poll(struct napi_struct *napi, int budget) tx_ring = ena_napi->tx_ring; rx_ring = ena_napi->rx_ring; - tx_ring->first_interrupt = ena_napi->first_interrupt; - rx_ring->first_interrupt = ena_napi->first_interrupt; - tx_budget = tx_ring->ring_size / ENA_TX_POLL_BUDGET_DIVIDER; if (!test_bit(ENA_FLAG_DEV_UP, &tx_ring->adapter->flags) || @@ -2003,7 +1997,8 @@ static irqreturn_t ena_intr_msix_io(int irq, void *data) { struct ena_napi *ena_napi = data; - ena_napi->first_interrupt = true; + /* Used to check HW health */ + WRITE_ONCE(ena_napi->first_interrupt, true); WRITE_ONCE(ena_napi->interrupts_masked, true); smp_wmb(); /* write interrupts_masked before calling napi */ @@ -3657,7 +3652,9 @@ static void ena_fw_reset_device(struct work_struct *work) static int check_for_rx_interrupt_queue(struct ena_adapter *adapter, struct ena_ring *rx_ring) { - if (likely(rx_ring->first_interrupt)) + struct ena_napi *ena_napi = container_of(rx_ring->napi, struct ena_napi, napi); + + if (likely(READ_ONCE(ena_napi->first_interrupt))) return 0; if (ena_com_cq_empty(rx_ring->ena_com_io_cq)) @@ -3681,6 +3678,7 @@ static int check_for_rx_interrupt_queue(struct ena_adapter *adapter, static int check_missing_comp_in_tx_queue(struct ena_adapter *adapter, struct ena_ring *tx_ring) { + struct ena_napi *ena_napi = container_of(tx_ring->napi, struct ena_napi, napi); struct ena_tx_buffer *tx_buf; unsigned long last_jiffies; u32 missed_tx = 0; @@ -3694,8 +3692,9 @@ static int check_missing_comp_in_tx_queue(struct ena_adapter *adapter, /* no pending Tx at this location */ continue; - if (unlikely(!tx_ring->first_interrupt && time_is_before_jiffies(last_jiffies + - 2 * adapter->missing_tx_completion_to))) { + if (unlikely(!READ_ONCE(ena_napi->first_interrupt) && + time_is_before_jiffies(last_jiffies + 2 * + adapter->missing_tx_completion_to))) { /* If after graceful period interrupt is still not * received, we schedule a reset */ diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.h b/drivers/net/ethernet/amazon/ena/ena_netdev.h index 74af15d..2175870 100644 --- a/drivers/net/ethernet/amazon/ena/ena_netdev.h +++ b/drivers/net/ethernet/amazon/ena/ena_netdev.h @@ -135,12 +135,12 @@ struct ena_irq { }; struct ena_napi { - struct napi_struct napi ____cacheline_aligned; + u8 first_interrupt ____cacheline_aligned; + u8 interrupts_masked; + struct napi_struct napi; struct ena_ring *tx_ring; struct ena_ring *rx_ring; struct ena_ring *xdp_ring; - bool first_interrupt; - bool interrupts_masked; u32 qid; struct dim dim; }; @@ -259,6 +259,10 @@ struct ena_ring { struct bpf_prog *xdp_bpf_prog; struct xdp_rxq_info xdp_rxq; spinlock_t xdp_tx_lock; /* synchronize XDP TX/Redirect traffic */ + /* Used for rx queues only to point to the xdp tx ring, to + * which traffic should be redirected from this rx ring. + */ + struct ena_ring *xdp_ring; u16 next_to_use; u16 next_to_clean; @@ -271,7 +275,6 @@ struct ena_ring { /* The maximum header length the device can handle */ u8 tx_max_header_size; - bool first_interrupt; bool disable_meta_caching; u16 no_interrupt_event_cnt; -- 2.7.4