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authorAlexander Duyck <alexander.h.duyck@intel.com>2012-09-13 08:28:01 +0200
committerJeff Kirsher <jeffrey.t.kirsher@intel.com>2012-09-22 11:50:24 +0200
commitf4128785b8f3f1fd7dc81b972661003d639a4676 (patch)
tree8d34f8c4b12cf6032fe135d073319c94af96c79c
parentigb: Remove logic that was doing NUMA pseudo-aware allocations (diff)
downloadlinux-f4128785b8f3f1fd7dc81b972661003d639a4676.tar.xz
linux-f4128785b8f3f1fd7dc81b972661003d639a4676.zip
igb: Change Tx cleanup loop to do/while instead of for
This change makes it so that Tx cleanup is done in a do/while loop instead of a for loop. The main motivation behind this is the fact that we should never be invoked with a budget less than 1 so we can skip checking the budget before processing the first descriptor. Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com> Tested-by: Aaron Brown <aaron.f.brown@intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
-rw-r--r--drivers/net/ethernet/intel/igb/igb_main.c28
1 files changed, 16 insertions, 12 deletions
diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index c9997d83de07..91f542c50f61 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -5690,7 +5690,7 @@ static bool igb_clean_tx_irq(struct igb_q_vector *q_vector)
struct igb_adapter *adapter = q_vector->adapter;
struct igb_ring *tx_ring = q_vector->tx.ring;
struct igb_tx_buffer *tx_buffer;
- union e1000_adv_tx_desc *tx_desc, *eop_desc;
+ union e1000_adv_tx_desc *tx_desc;
unsigned int total_bytes = 0, total_packets = 0;
unsigned int budget = q_vector->tx.work_limit;
unsigned int i = tx_ring->next_to_clean;
@@ -5702,16 +5702,16 @@ static bool igb_clean_tx_irq(struct igb_q_vector *q_vector)
tx_desc = IGB_TX_DESC(tx_ring, i);
i -= tx_ring->count;
- for (; budget; budget--) {
- eop_desc = tx_buffer->next_to_watch;
-
- /* prevent any other reads prior to eop_desc */
- rmb();
+ do {
+ union e1000_adv_tx_desc *eop_desc = tx_buffer->next_to_watch;
/* if next_to_watch is not set then there is no work pending */
if (!eop_desc)
break;
+ /* prevent any other reads prior to eop_desc */
+ rmb();
+
/* if DD is not set pending work has not been completed */
if (!(eop_desc->wb.status & cpu_to_le32(E1000_TXD_STAT_DD)))
break;
@@ -5767,7 +5767,13 @@ static bool igb_clean_tx_irq(struct igb_q_vector *q_vector)
tx_buffer = tx_ring->tx_buffer_info;
tx_desc = IGB_TX_DESC(tx_ring, 0);
}
- }
+
+ /* issue prefetch for next Tx descriptor */
+ prefetch(tx_desc);
+
+ /* update budget accounting */
+ budget--;
+ } while (likely(budget));
netdev_tx_completed_queue(txring_txq(tx_ring),
total_packets, total_bytes);
@@ -5783,12 +5789,10 @@ static bool igb_clean_tx_irq(struct igb_q_vector *q_vector)
if (test_bit(IGB_RING_FLAG_TX_DETECT_HANG, &tx_ring->flags)) {
struct e1000_hw *hw = &adapter->hw;
- eop_desc = tx_buffer->next_to_watch;
-
/* Detect a transmit hang in hardware, this serializes the
* check with the clearing of time_stamp and movement of i */
clear_bit(IGB_RING_FLAG_TX_DETECT_HANG, &tx_ring->flags);
- if (eop_desc &&
+ if (tx_buffer->next_to_watch &&
time_after(jiffies, tx_buffer->time_stamp +
(adapter->tx_timeout_factor * HZ)) &&
!(rd32(E1000_STATUS) & E1000_STATUS_TXOFF)) {
@@ -5812,9 +5816,9 @@ static bool igb_clean_tx_irq(struct igb_q_vector *q_vector)
tx_ring->next_to_use,
tx_ring->next_to_clean,
tx_buffer->time_stamp,
- eop_desc,
+ tx_buffer->next_to_watch,
jiffies,
- eop_desc->wb.status);
+ tx_buffer->next_to_watch->wb.status);
netif_stop_subqueue(tx_ring->netdev,
tx_ring->queue_index);