From 53a76b58b66e77164c4a79c38da49b808d67477e Mon Sep 17 00:00:00 2001
From: Christian Lamparter <chunkeey@googlemail.com>
Date: Sun, 29 Nov 2009 00:52:51 +0100
Subject: [PATCH] ar9170: improve network latency
AR9170 has the bad habit of choking when traffic builds up.
Tests have shown that this can partially be attributed to
a huge buildup of backlogged frames.
Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
---
drivers/net/wireless/ath/ar9170/ar9170.h | 2 ++
drivers/net/wireless/ath/ar9170/main.c | 34 +++++++++++-------------
2 files changed, 18 insertions(+), 18 deletions(-)
diff --git a/drivers/net/wireless/ath/ar9170/ar9170.h b/drivers/net/wireless/ath/ar9170/ar9170.h
index d95a7d47af04..44c54b834a00 100644
--- a/drivers/net/wireless/ath/ar9170/ar9170.h
+++ b/drivers/net/wireless/ath/ar9170/ar9170.h
@@ -152,6 +152,8 @@ struct ar9170_sta_tid {
#define AR9170_NUM_TX_STATUS 128
#define AR9170_NUM_TX_AGG_MAX 30
+#define AR9170_NUM_TX_LIMIT_HARD AR9170_TXQ_DEPTH
+#define AR9170_NUM_TX_LIMIT_SOFT (AR9170_TXQ_DEPTH - 10)
struct ar9170 {
struct ieee80211_hw *hw;
diff --git a/drivers/net/wireless/ath/ar9170/main.c b/drivers/net/wireless/ath/ar9170/main.c
index cbf59b1590bf..3cec2f16c657 100644
--- a/drivers/net/wireless/ath/ar9170/main.c
+++ b/drivers/net/wireless/ath/ar9170/main.c
@@ -430,7 +430,7 @@ void ar9170_tx_callback(struct ar9170 *ar, struct sk_buff *skb)
spin_lock_irqsave(&ar->tx_stats_lock, flags);
ar->tx_stats[queue].len--;
- if (skb_queue_empty(&ar->tx_pending[queue])) {
+ if (ar->tx_stats[queue].len < AR9170_NUM_TX_LIMIT_SOFT) {
#ifdef AR9170_QUEUE_STOP_DEBUG
printk(KERN_DEBUG "%s: wake queue %d\n",
wiphy_name(ar->hw->wiphy), queue);
@@ -1716,6 +1716,21 @@ static void ar9170_tx(struct ar9170 *ar)
for (i = 0; i < __AR9170_NUM_TXQ; i++) {
spin_lock_irqsave(&ar->tx_stats_lock, flags);
+ frames = min(ar->tx_stats[i].limit - ar->tx_stats[i].len,
+ skb_queue_len(&ar->tx_pending[i]));
+
+ if (remaining_space < frames) {
+#ifdef AR9170_QUEUE_DEBUG
+ printk(KERN_DEBUG "%s: tx quota reached queue:%d, "
+ "remaining slots:%d, needed:%d\n",
+ wiphy_name(ar->hw->wiphy), i, remaining_space,
+ frames);
+#endif /* AR9170_QUEUE_DEBUG */
+ frames = remaining_space;
+ }
+
+ ar->tx_stats[i].len += frames;
+ ar->tx_stats[i].count += frames;
if (ar->tx_stats[i].len >= ar->tx_stats[i].limit) {
#ifdef AR9170_QUEUE_DEBUG
printk(KERN_DEBUG "%s: queue %d full\n",
@@ -1733,25 +1748,8 @@ static void ar9170_tx(struct ar9170 *ar)
__ar9170_dump_txstats(ar);
#endif /* AR9170_QUEUE_STOP_DEBUG */
ieee80211_stop_queue(ar->hw, i);
- spin_unlock_irqrestore(&ar->tx_stats_lock, flags);
- continue;
- }
-
- frames = min(ar->tx_stats[i].limit - ar->tx_stats[i].len,
- skb_queue_len(&ar->tx_pending[i]));
-
- if (remaining_space < frames) {
-#ifdef AR9170_QUEUE_DEBUG
- printk(KERN_DEBUG "%s: tx quota reached queue:%d, "
- "remaining slots:%d, needed:%d\n",
- wiphy_name(ar->hw->wiphy), i, remaining_space,
- frames);
-#endif /* AR9170_QUEUE_DEBUG */
- frames = remaining_space;
}
- ar->tx_stats[i].len += frames;
- ar->tx_stats[i].count += frames;
spin_unlock_irqrestore(&ar->tx_stats_lock, flags);
if (!frames)
--
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