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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 <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
This commit is contained in:
Jacob Keller 2016-06-09 14:56:05 -07:00 committed by Jeff Kirsher
parent e59a393d08
commit 5b9e4432db
3 changed files with 17 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/net/ethernet/intel/fm10k/fm10k.h
View File

@ -458,7 +458,7 @@ __be16 fm10k_tx_encap_offload(struct sk_buff *skb);
netdev_tx_t fm10k_xmit_frame_ring(struct sk_buff *skb, netdev_tx_t fm10k_xmit_frame_ring(struct sk_buff *skb,
struct fm10k_ring *tx_ring); struct fm10k_ring *tx_ring);
void fm10k_tx_timeout_reset(struct fm10k_intfc *interface); 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); bool fm10k_check_tx_hang(struct fm10k_ring *tx_ring);
void fm10k_alloc_rx_buffers(struct fm10k_ring *rx_ring, u16 cleaned_count); void fm10k_alloc_rx_buffers(struct fm10k_ring *rx_ring, u16 cleaned_count);

19
drivers/net/ethernet/intel/fm10k/fm10k_main.c
View File

@ -1128,13 +1128,24 @@ static u64 fm10k_get_tx_completed(struct fm10k_ring *ring)
return ring->stats.packets; 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_intfc *interface = ring->q_vector->interface;
struct fm10k_hw *hw = &interface->hw; struct fm10k_hw *hw = &interface->hw;
u32 head, tail;
u32 head = fm10k_read_reg(hw, FM10K_TDH(ring->reg_idx)); if (likely(in_sw)) {
u32 tail = fm10k_read_reg(hw, FM10K_TDT(ring->reg_idx)); 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; 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 = fm10k_get_tx_completed(tx_ring);
u32 tx_done_old = tx_ring->tx_stats.tx_done_old; 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); clear_check_for_tx_hang(tx_ring);

2
drivers/net/ethernet/intel/fm10k/fm10k_pci.c
View File

@ -1699,7 +1699,7 @@ void fm10k_down(struct fm10k_intfc *interface)
/* start checking at the last ring to have pending Tx */ /* start checking at the last ring to have pending Tx */
for (; i < interface->num_tx_queues; i++) 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; break;
/* if all the queues are drained, we can break now */ /* if all the queues are drained, we can break now */