iwlwifi: improve TX cache footprint

Having cmd[], meta[] and skbs[] as separate arrays
in the TX queue structure is cache inefficient as
we need the data for a given entry together.

To improve this, create an array with these three
members (allocate meta as part of that struct) so
we have the data we need together located together
improving cache footprint.

The downside is that we need to allocate a lot of
memory in one chunk, about 10KiB (on 64-bit) which
isn't very efficient.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>

1 files changed, 16 insertions, 15 deletions

diff --git a/drivers/net/wireless/iwlwifi/iwl-trans-pcie-tx.c b/drivers/net/wireless/iwlwifi/iwl-trans-pcie-tx.c
index bb0a314..1b2aed6 100644
--- a/drivers/net/wireless/iwlwifi/iwl-trans-pcie-tx.c
+++ b/drivers/net/wireless/iwlwifi/iwl-trans-pcie-tx.c
@@ -58,7 +58,7 @@ void iwl_trans_txq_update_byte_cnt_tbl(struct iwl_trans *trans,
 	u16 len = byte_cnt + IWL_TX_CRC_SIZE + IWL_TX_DELIMITER_SIZE;
 	__le16 bc_ent;
 	struct iwl_tx_cmd *tx_cmd =
-		(struct iwl_tx_cmd *) txq->cmd[txq->q.write_ptr]->payload;
+		(void *) txq->entries[txq->q.write_ptr].cmd->payload;
 
 	scd_bc_tbl = trans_pcie->scd_bc_tbls.addr;
 
@@ -221,13 +221,14 @@ void iwlagn_txq_free_tfd(struct iwl_trans *trans, struct iwl_tx_queue *txq,
 
 	lockdep_assert_held(&txq->lock);
 
-	iwlagn_unmap_tfd(trans, &txq->meta[index], &tfd_tmp[index], dma_dir);
+	iwlagn_unmap_tfd(trans, &txq->entries[index].meta,
+			 &tfd_tmp[index], dma_dir);
 
 	/* free SKB */
-	if (txq->skbs) {
+	if (txq->entries) {
 		struct sk_buff *skb;
 
-		skb = txq->skbs[index];
+		skb = txq->entries[index].skb;
 
 		/* Can be called from irqs-disabled context
 		 * If skb is not NULL, it means that the whole queue is being
@@ -235,7 +236,7 @@ void iwlagn_txq_free_tfd(struct iwl_trans *trans, struct iwl_tx_queue *txq,
 		 */
 		if (skb) {
 			iwl_op_mode_free_skb(trans->op_mode, skb);
-			txq->skbs[index] = NULL;
+			txq->entries[index].skb = NULL;
 		}
 	}
 }
@@ -358,7 +359,7 @@ static void iwlagn_txq_inval_byte_cnt_tbl(struct iwl_trans *trans,
 	u8 sta_id = 0;
 	__le16 bc_ent;
 	struct iwl_tx_cmd *tx_cmd =
-		(struct iwl_tx_cmd *) txq->cmd[txq->q.read_ptr]->payload;
+		(void *)txq->entries[txq->q.read_ptr].cmd->payload;
 
 	WARN_ON(read_ptr >= TFD_QUEUE_SIZE_MAX);
 
@@ -578,8 +579,8 @@ static int iwl_enqueue_hcmd(struct iwl_trans *trans, struct iwl_host_cmd *cmd)
 	}
 
 	idx = get_cmd_index(q, q->write_ptr);
-	out_cmd = txq->cmd[idx];
-	out_meta = &txq->meta[idx];
+	out_cmd = txq->entries[idx].cmd;
+	out_meta = &txq->entries[idx].meta;
 
 	memset(out_meta, 0, sizeof(*out_meta));	/* re-initialize to NULL */
 	if (cmd->flags & CMD_WANT_SKB)
@@ -772,8 +773,8 @@ void iwl_tx_cmd_complete(struct iwl_trans *trans, struct iwl_rx_cmd_buffer *rxb,
 	spin_lock(&txq->lock);
 
 	cmd_index = get_cmd_index(&txq->q, index);
-	cmd = txq->cmd[cmd_index];
-	meta = &txq->meta[cmd_index];
+	cmd = txq->entries[cmd_index].cmd;
+	meta = &txq->entries[cmd_index].meta;
 
 	iwlagn_unmap_tfd(trans, meta, &txq->tfds[index],
 			 DMA_BIDIRECTIONAL);
@@ -905,8 +906,8 @@ cancel:
 		 * in later, it will possibly set an invalid
 		 * address (cmd->meta.source).
 		 */
-		trans_pcie->txq[trans_pcie->cmd_queue].meta[cmd_idx].flags &=
-							~CMD_WANT_SKB;
+		trans_pcie->txq[trans_pcie->cmd_queue].
+			entries[cmd_idx].meta.flags &= ~CMD_WANT_SKB;
 	}
 
 	if (cmd->resp_pkt) {
@@ -961,12 +962,12 @@ int iwl_tx_queue_reclaim(struct iwl_trans *trans, int txq_id, int index,
 	     q->read_ptr != index;
 	     q->read_ptr = iwl_queue_inc_wrap(q->read_ptr, q->n_bd)) {
 
-		if (WARN_ON_ONCE(txq->skbs[txq->q.read_ptr] == NULL))
+		if (WARN_ON_ONCE(txq->entries[txq->q.read_ptr].skb == NULL))
 			continue;
 
-		__skb_queue_tail(skbs, txq->skbs[txq->q.read_ptr]);
+		__skb_queue_tail(skbs, txq->entries[txq->q.read_ptr].skb);
 
-		txq->skbs[txq->q.read_ptr] = NULL;
+		txq->entries[txq->q.read_ptr].skb = NULL;
 
 		iwlagn_txq_inval_byte_cnt_tbl(trans, txq);