Previously, the iwlwifi driver filled its transmit queue until it
reached a high-water mark, and then stopped until it had fallen to a
low-water mark. This basic logic makes sense for interrupt mitigation
-- you might not want to wake up the CPU after every packet, but
instead wait until a batch of packets has been sent -- except the
iwlwifi driver doesn't actually do any interrupt mitigation; the CPU
wakes up after every packet transmitted anyway. So we simplify the
code to maintain only a single limit on total queue length, and
whenever we drop below that limit we allow more packets in.
This patch should have no user-visible effect.
Signed-off-by: Nathaniel J. Smith <njs@xxxxxxxxx>
---
drivers/net/wireless/iwlwifi/iwl-3945.c | 4 ++--
drivers/net/wireless/iwlwifi/iwl-4965.c | 4 ++--
drivers/net/wireless/iwlwifi/iwl-agn-lib.c | 4 ++--
drivers/net/wireless/iwlwifi/iwl-agn-tx.c | 6 +++---
drivers/net/wireless/iwlwifi/iwl-dev.h | 2 --
drivers/net/wireless/iwlwifi/iwl-tx.c | 18 +++++++-----------
drivers/net/wireless/iwlwifi/iwl3945-base.c | 4 ++--
7 files changed, 18 insertions(+), 24 deletions(-)
diff --git a/drivers/net/wireless/iwlwifi/iwl-3945.c b/drivers/net/wireless/iwlwifi/iwl-3945.c
index 5b6932c..6d2fb06 100644
--- a/drivers/net/wireless/iwlwifi/iwl-3945.c
+++ b/drivers/net/wireless/iwlwifi/iwl-3945.c
@@ -274,7 +274,7 @@ int iwl3945_rs_next_rate(struct iwl_priv *priv, int rate)
*
* When FW advances 'R' index, all entries between old and new 'R' index
* need to be reclaimed. As result, some free space forms. If there is
- * enough free space (> low mark), wake the stack that feeds us.
+ * enough free space (> high mark), wake the stack that feeds us.
*/
static void iwl3945_tx_queue_reclaim(struct iwl_priv *priv,
int txq_id, int index)
@@ -294,7 +294,7 @@ static void iwl3945_tx_queue_reclaim(struct iwl_priv *priv,
priv->cfg->ops->lib->txq_free_tfd(priv, txq);
}
- if (iwl_queue_space(q) > q->low_mark && (txq_id >= 0) &&
+ if (iwl_queue_space(q) > q->high_mark && (txq_id >= 0) &&
(txq_id != IWL39_CMD_QUEUE_NUM) &&
priv->mac80211_registered)
iwl_wake_queue(priv, txq);
diff --git a/drivers/net/wireless/iwlwifi/iwl-4965.c b/drivers/net/wireless/iwlwifi/iwl-4965.c
index 8998ed1..b8955d7 100644
--- a/drivers/net/wireless/iwlwifi/iwl-4965.c
+++ b/drivers/net/wireless/iwlwifi/iwl-4965.c
@@ -2230,7 +2230,7 @@ static void iwl4965_rx_reply_tx(struct iwl_priv *priv,
tid, freed);
if (priv->mac80211_registered &&
- (iwl_queue_space(&txq->q) > txq->q.low_mark) &&
+ (iwl_queue_space(&txq->q) > txq->q.high_mark) &&
(agg->state != IWL_EMPTYING_HW_QUEUE_DELBA))
iwl_wake_queue(priv, txq);
}
@@ -2255,7 +2255,7 @@ static void iwl4965_rx_reply_tx(struct iwl_priv *priv,
IWL_DEBUG_TX_REPLY(priv, "Station not known\n");
if (priv->mac80211_registered &&
- (iwl_queue_space(&txq->q) > txq->q.low_mark))
+ (iwl_queue_space(&txq->q) > txq->q.high_mark))
iwl_wake_queue(priv, txq);
}
if (qc && likely(sta_id != IWL_INVALID_STATION))
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-lib.c b/drivers/net/wireless/iwlwifi/iwl-agn-lib.c
index 3aa4864..f229543 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn-lib.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-lib.c
@@ -445,7 +445,7 @@ static void iwlagn_rx_reply_tx(struct iwl_priv *priv,
iwl_free_tfds_in_queue(priv, sta_id, tid, freed);
if (priv->mac80211_registered &&
- (iwl_queue_space(&txq->q) > txq->q.low_mark) &&
+ (iwl_queue_space(&txq->q) > txq->q.high_mark) &&
(agg->state != IWL_EMPTYING_HW_QUEUE_DELBA))
iwl_wake_queue(priv, txq);
}
@@ -455,7 +455,7 @@ static void iwlagn_rx_reply_tx(struct iwl_priv *priv,
iwl_free_tfds_in_queue(priv, sta_id, tid, freed);
if (priv->mac80211_registered &&
- (iwl_queue_space(&txq->q) > txq->q.low_mark))
+ (iwl_queue_space(&txq->q) > txq->q.high_mark))
iwl_wake_queue(priv, txq);
}
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-tx.c b/drivers/net/wireless/iwlwifi/iwl-agn-tx.c
index 266490d..bffba7e 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn-tx.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-tx.c
@@ -637,7 +637,7 @@ int iwlagn_tx_skb(struct iwl_priv *priv, struct sk_buff *skb)
txq = &priv->txq[txq_id];
q = &txq->q;
- if (unlikely(iwl_queue_space(q) < q->high_mark)) {
+ if (unlikely(iwl_queue_space(q) <= q->high_mark)) {
spin_unlock(&priv->sta_lock);
goto drop_unlock;
}
@@ -788,7 +788,7 @@ int iwlagn_tx_skb(struct iwl_priv *priv, struct sk_buff *skb)
if (sta_priv && sta_priv->client && !is_agg)
atomic_inc(&sta_priv->pending_frames);
- if ((iwl_queue_space(q) < q->high_mark) && priv->mac80211_registered) {
+ if ((iwl_queue_space(q) <= q->high_mark) && priv->mac80211_registered) {
if (wait_write_ptr) {
spin_lock_irqsave(&priv->lock, flags);
txq->need_update = 1;
@@ -1431,7 +1431,7 @@ void iwlagn_rx_reply_compressed_ba(struct iwl_priv *priv,
int freed = iwlagn_tx_queue_reclaim(priv, scd_flow, index);
iwl_free_tfds_in_queue(priv, sta_id, tid, freed);
- if ((iwl_queue_space(&txq->q) > txq->q.low_mark) &&
+ if ((iwl_queue_space(&txq->q) > txq->q.high_mark) &&
priv->mac80211_registered &&
(agg->state != IWL_EMPTYING_HW_QUEUE_DELBA))
iwl_wake_queue(priv, txq);
diff --git a/drivers/net/wireless/iwlwifi/iwl-dev.h b/drivers/net/wireless/iwlwifi/iwl-dev.h
index ecfbef4..eb6586d 100644
--- a/drivers/net/wireless/iwlwifi/iwl-dev.h
+++ b/drivers/net/wireless/iwlwifi/iwl-dev.h
@@ -134,8 +134,6 @@ struct iwl_queue {
dma_addr_t dma_addr; /* physical addr for BD's */
int n_window; /* safe queue window */
u32 id;
- int low_mark; /* low watermark, resume queue if free
- * space more than this */
int high_mark; /* high watermark, stop queue if free
* space less than this */
};
diff --git a/drivers/net/wireless/iwlwifi/iwl-tx.c b/drivers/net/wireless/iwlwifi/iwl-tx.c
index 073b6ce..78a9896 100644
--- a/drivers/net/wireless/iwlwifi/iwl-tx.c
+++ b/drivers/net/wireless/iwlwifi/iwl-tx.c
@@ -210,10 +210,10 @@ EXPORT_SYMBOL(iwl_cmd_queue_free);
* The device reads or writes the data in the queues via the device's several
* DMA/FIFO channels. Each queue is mapped to a single DMA channel.
*
- * For Tx queue, there are low mark and high mark limits. If, after queuing
- * the packet for Tx, free space become < low mark, Tx queue stopped. When
- * reclaiming packets (on 'tx done IRQ), if free space become > high mark,
- * Tx queue resumed.
+ * For Tx queue, there is a high mark limit. If, after queuing the packet for
+ * Tx, free space becomes <= high mark, Tx queue stopped. When reclaiming
+ * packets (on 'tx done IRQ), if free space become > high mark, Tx queue
+ * resumed.
*
* See more detailed info in iwl-4965-hw.h.
***************************************************/
@@ -237,7 +237,7 @@ EXPORT_SYMBOL(iwl_queue_space);
/**
- * iwl_queue_init - Initialize queue's high/low-water and read/write indexes
+ * iwl_queue_init - Initialize queue's high-water and read/write indexes
*/
static int iwl_queue_init(struct iwl_priv *priv, struct iwl_queue *q,
int count, int slots_num, u32 id)
@@ -254,10 +254,6 @@ static int iwl_queue_init(struct iwl_priv *priv, struct iwl_queue *q,
* get_cmd_index is broken. */
BUG_ON(!is_power_of_2(slots_num));
- q->low_mark = q->n_window / 4;
- if (q->low_mark < 4)
- q->low_mark = 4;
-
q->high_mark = q->n_window / 8;
if (q->high_mark < 2)
q->high_mark = 2;
@@ -368,7 +364,7 @@ int iwl_tx_queue_init(struct iwl_priv *priv, struct iwl_tx_queue *txq,
* iwl_queue_inc_wrap and iwl_queue_dec_wrap are broken. */
BUILD_BUG_ON(TFD_QUEUE_SIZE_MAX & (TFD_QUEUE_SIZE_MAX - 1));
- /* Initialize queue's high/low-water marks, and head/tail indexes */
+ /* Initialize queue's high-water mark, and head/tail indexes */
iwl_queue_init(priv, &txq->q, TFD_QUEUE_SIZE_MAX, slots_num, txq_id);
/* Tell device where to find queue */
@@ -547,7 +543,7 @@ int iwl_enqueue_hcmd(struct iwl_priv *priv, struct iwl_host_cmd *cmd)
*
* When FW advances 'R' index, all entries between old and new 'R' index
* need to be reclaimed. As result, some free space forms. If there is
- * enough free space (> low mark), wake the stack that feeds us.
+ * enough free space (> high mark), wake the stack that feeds us.
*/
static void iwl_hcmd_queue_reclaim(struct iwl_priv *priv, int txq_id,
int idx, int cmd_idx)
diff --git a/drivers/net/wireless/iwlwifi/iwl3945-base.c b/drivers/net/wireless/iwlwifi/iwl3945-base.c
index adcef73..e0d4c83 100644
--- a/drivers/net/wireless/iwlwifi/iwl3945-base.c
+++ b/drivers/net/wireless/iwlwifi/iwl3945-base.c
@@ -536,7 +536,7 @@ static int iwl3945_tx_skb(struct iwl_priv *priv, struct sk_buff *skb)
txq = &priv->txq[txq_id];
q = &txq->q;
- if ((iwl_queue_space(q) < q->high_mark))
+ if ((iwl_queue_space(q) <= q->high_mark))
goto drop;
spin_lock_irqsave(&priv->lock, flags);
@@ -646,7 +646,7 @@ static int iwl3945_tx_skb(struct iwl_priv *priv, struct sk_buff *skb)
iwl_txq_update_write_ptr(priv, txq);
spin_unlock_irqrestore(&priv->lock, flags);
- if ((iwl_queue_space(q) < q->high_mark)
+ if ((iwl_queue_space(q) <= q->high_mark)
&& priv->mac80211_registered) {
if (wait_write_ptr) {
spin_lock_irqsave(&priv->lock, flags);
--
1.7.1
--
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