From 5b9e4432db038eefcafe2be468e3adaf2edbbe91 Mon Sep 17 00:00:00 2001 From: Jacob Keller Date: Thu, 9 Jun 2016 14:56:05 -0700 Subject: [PATCH] fm10k: use software values when checking for Tx hangs in hot path A previous patch added support to check for hardware Tx pending in the fm10k_down routine. This support was intended to ensure that we accurately check what the hardware state is. However, checking for Tx hangs in this manor during the hotpath results in a large performance hit. Avoid this by making the hotpath check use the SW counters instead. Fixes: a0f53cf49cb0 ("fm10k: use actual hardware registers when checking for pending Tx", 2016-06-08) Signed-off-by: Jacob Keller Tested-by: Krishneil Singh Signed-off-by: Jeff Kirsher --- drivers/net/ethernet/intel/fm10k/fm10k.h | 2 +- drivers/net/ethernet/intel/fm10k/fm10k_main.c | 19 +++++++++++++++---- drivers/net/ethernet/intel/fm10k/fm10k_pci.c | 2 +- 3 files changed, 17 insertions(+), 6 deletions(-) diff --git a/drivers/net/ethernet/intel/fm10k/fm10k.h b/drivers/net/ethernet/intel/fm10k/fm10k.h index c4cf08dcf5af..75429f2bbc97 100644 --- a/drivers/net/ethernet/intel/fm10k/fm10k.h +++ b/drivers/net/ethernet/intel/fm10k/fm10k.h @@ -458,7 +458,7 @@ __be16 fm10k_tx_encap_offload(struct sk_buff *skb); netdev_tx_t fm10k_xmit_frame_ring(struct sk_buff *skb, struct fm10k_ring *tx_ring); void fm10k_tx_timeout_reset(struct fm10k_intfc *interface); -u64 fm10k_get_tx_pending(struct fm10k_ring *ring); +u64 fm10k_get_tx_pending(struct fm10k_ring *ring, bool in_sw); bool fm10k_check_tx_hang(struct fm10k_ring *tx_ring); void fm10k_alloc_rx_buffers(struct fm10k_ring *rx_ring, u16 cleaned_count); diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_main.c b/drivers/net/ethernet/intel/fm10k/fm10k_main.c index e9767b6366a8..0d6e69d1586a 100644 --- a/drivers/net/ethernet/intel/fm10k/fm10k_main.c +++ b/drivers/net/ethernet/intel/fm10k/fm10k_main.c @@ -1128,13 +1128,24 @@ static u64 fm10k_get_tx_completed(struct fm10k_ring *ring) return ring->stats.packets; } -u64 fm10k_get_tx_pending(struct fm10k_ring *ring) +/** + * fm10k_get_tx_pending - how many Tx descriptors not processed + * @ring: the ring structure + * @in_sw: is tx_pending being checked in SW or in HW? + */ +u64 fm10k_get_tx_pending(struct fm10k_ring *ring, bool in_sw) { struct fm10k_intfc *interface = ring->q_vector->interface; struct fm10k_hw *hw = &interface->hw; + u32 head, tail; - u32 head = fm10k_read_reg(hw, FM10K_TDH(ring->reg_idx)); - u32 tail = fm10k_read_reg(hw, FM10K_TDT(ring->reg_idx)); + if (likely(in_sw)) { + head = ring->next_to_clean; + tail = ring->next_to_use; + } else { + head = fm10k_read_reg(hw, FM10K_TDH(ring->reg_idx)); + tail = fm10k_read_reg(hw, FM10K_TDT(ring->reg_idx)); + } return ((head <= tail) ? tail : tail + ring->count) - head; } @@ -1143,7 +1154,7 @@ bool fm10k_check_tx_hang(struct fm10k_ring *tx_ring) { u32 tx_done = fm10k_get_tx_completed(tx_ring); u32 tx_done_old = tx_ring->tx_stats.tx_done_old; - u32 tx_pending = fm10k_get_tx_pending(tx_ring); + u32 tx_pending = fm10k_get_tx_pending(tx_ring, true); clear_check_for_tx_hang(tx_ring); diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_pci.c b/drivers/net/ethernet/intel/fm10k/fm10k_pci.c index 377a3fbb779f..20c2a0cf83da 100644 --- a/drivers/net/ethernet/intel/fm10k/fm10k_pci.c +++ b/drivers/net/ethernet/intel/fm10k/fm10k_pci.c @@ -1699,7 +1699,7 @@ void fm10k_down(struct fm10k_intfc *interface) /* start checking at the last ring to have pending Tx */ for (; i < interface->num_tx_queues; i++) - if (fm10k_get_tx_pending(interface->tx_ring[i])) + if (fm10k_get_tx_pending(interface->tx_ring[i], false)) break; /* if all the queues are drained, we can break now */ -- 2.39.5