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ath9k: backport dynack improvements
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Close cooperation with Lorenzo Bianconi resulted
in these patches which fix all remaining seen issues
when using dynack.

Fix link losses when:
- Late Ack's are not seen or not present
- switching from too low static coverage class to dynack on a live link

These are fixed by setting the Ack Timeout/Slottime to
the max possible value for the currently used channel width when
a new station has been discovered.

When traffic flows, dynack is able to adjust to optimal values
within a few packets received (typically < 1 second)

These changes have been thoroughly tested on ~60 offshore devices
all interconnected using mesh over IBSS and dynack enabled on all.

Distances between devices varied from <100m up to ~35km

Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
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Koen Vandeputte committed Aug 28, 2019
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94 changes: 94 additions & 0 deletions ...ernel/mac80211/patches/ath/558-ath9k-dynack-introduce-ath_dynack_set_timeout-routin.patch
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@@ -0,0 +1,94 @@
From 4420866ef1b602682b009e0186fbb8aefd2125be Mon Sep 17 00:00:00 2001
From: Lorenzo Bianconi <lorenzo@kernel.org>
Date: Tue, 20 Aug 2019 18:20:19 +0200
Subject: [PATCH 1/4] ath9k: dynack: introduce ath_dynack_set_timeout routine

Introduce ath_dynack_set_timeout routine to configure slottime/ack/cts
timeouts and remove duplicated code

Tested-by: Koen Vandeputte <koen.vandeputte@ncentric.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
drivers/net/wireless/ath/ath9k/dynack.c | 37 ++++++++++++++-----------
1 file changed, 21 insertions(+), 16 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/dynack.c b/drivers/net/wireless/ath/ath9k/dynack.c
index f112fa5b2eac..38dbe25919f7 100644
--- a/drivers/net/wireless/ath/ath9k/dynack.c
+++ b/drivers/net/wireless/ath/ath9k/dynack.c
@@ -78,6 +78,24 @@ static inline bool ath_dynack_bssidmask(struct ath_hw *ah, const u8 *mac)
return true;
}

+/**
+ * ath_dynack_set_timeout - configure timeouts/slottime registers
+ * @ah: ath hw
+ * @to: timeout value
+ *
+ */
+static void ath_dynack_set_timeout(struct ath_hw *ah, int to)
+{
+ struct ath_common *common = ath9k_hw_common(ah);
+ int slottime = (to - 3) / 2;
+
+ ath_dbg(common, DYNACK, "ACK timeout %u slottime %u\n",
+ to, slottime);
+ ath9k_hw_setslottime(ah, slottime);
+ ath9k_hw_set_ack_timeout(ah, to);
+ ath9k_hw_set_cts_timeout(ah, to);
+}
+
/**
* ath_dynack_compute_ackto - compute ACK timeout as the maximum STA timeout
* @ah: ath hw
@@ -86,7 +104,6 @@ static inline bool ath_dynack_bssidmask(struct ath_hw *ah, const u8 *mac)
*/
static void ath_dynack_compute_ackto(struct ath_hw *ah)
{
- struct ath_common *common = ath9k_hw_common(ah);
struct ath_dynack *da = &ah->dynack;
struct ath_node *an;
int to = 0;
@@ -96,15 +113,8 @@ static void ath_dynack_compute_ackto(struct ath_hw *ah)
to = an->ackto;

if (to && da->ackto != to) {
- u32 slottime;
-
- slottime = (to - 3) / 2;
+ ath_dynack_set_timeout(ah, to);
da->ackto = to;
- ath_dbg(common, DYNACK, "ACK timeout %u slottime %u\n",
- da->ackto, slottime);
- ath9k_hw_setslottime(ah, slottime);
- ath9k_hw_set_ack_timeout(ah, da->ackto);
- ath9k_hw_set_cts_timeout(ah, da->ackto);
}
}

@@ -198,10 +208,7 @@ void ath_dynack_sample_tx_ts(struct ath_hw *ah, struct sk_buff *skb,
ieee80211_is_assoc_resp(hdr->frame_control) ||
ieee80211_is_auth(hdr->frame_control)) {
ath_dbg(common, DYNACK, "late ack\n");
-
- ath9k_hw_setslottime(ah, (LATEACK_TO - 3) / 2);
- ath9k_hw_set_ack_timeout(ah, LATEACK_TO);
- ath9k_hw_set_cts_timeout(ah, LATEACK_TO);
+ ath_dynack_set_timeout(ah, LATEACK_TO);
if (sta) {
struct ath_node *an;

@@ -340,9 +347,7 @@ void ath_dynack_reset(struct ath_hw *ah)
da->ack_rbf.h_rb = 0;

/* init acktimeout */
- ath9k_hw_setslottime(ah, (ackto - 3) / 2);
- ath9k_hw_set_ack_timeout(ah, ackto);
- ath9k_hw_set_cts_timeout(ah, ackto);
+ ath_dynack_set_timeout(ah, ackto);
}
EXPORT_SYMBOL(ath_dynack_reset);

--
2.17.1

32 changes: 32 additions & 0 deletions ...ernel/mac80211/patches/ath/559-ath9k-dynack-properly-set-last-timeout-timestamp-in-.patch
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@@ -0,0 +1,32 @@
From e5b56ce50eab31d24df6a70cf025db3acc4aa3ac Mon Sep 17 00:00:00 2001
From: Lorenzo Bianconi <lorenzo@kernel.org>
Date: Tue, 20 Aug 2019 18:20:20 +0200
Subject: [PATCH 2/4] ath9k: dynack: properly set last timeout timestamp in
ath_dynack_reset

Add compute timeout to last computation timestamp in
ath_dynack_reset in order to not run ath_dynack_compute_ackto
immediately

Tested-by: Koen Vandeputte <koen.vandeputte@ncentric.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
drivers/net/wireless/ath/ath9k/dynack.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath9k/dynack.c b/drivers/net/wireless/ath/ath9k/dynack.c
index 38dbe25919f7..398ea872751f 100644
--- a/drivers/net/wireless/ath/ath9k/dynack.c
+++ b/drivers/net/wireless/ath/ath9k/dynack.c
@@ -338,7 +338,7 @@ void ath_dynack_reset(struct ath_hw *ah)
u32 ackto = 9 + 16 + 64;
struct ath_dynack *da = &ah->dynack;

- da->lto = jiffies;
+ da->lto = jiffies + COMPUTE_TO;
da->ackto = ackto;

da->st_rbf.t_rb = 0;
--
2.17.1

96 changes: 96 additions & 0 deletions ...ernel/mac80211/patches/ath/560-ath9k-dynack-set-max-timeout-according-to-channel-wi.patch
View file
@@ -0,0 +1,96 @@
From 3f737abb7d53cc80d619a3b4a30b6fa63cdc8df7 Mon Sep 17 00:00:00 2001
From: Lorenzo Bianconi <lorenzo@kernel.org>
Date: Tue, 20 Aug 2019 18:20:21 +0200
Subject: [PATCH 3/4] ath9k: dynack: set max timeout according to channel width

Compute maximum configurable ackimeout/ctstimeout according to channel
width (clockrate)

Tested-by: Koen Vandeputte <koen.vandeputte@ncentric.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
drivers/net/wireless/ath/ath9k/dynack.c | 38 +++++++++++++++++++------
1 file changed, 30 insertions(+), 8 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/dynack.c b/drivers/net/wireless/ath/ath9k/dynack.c
index 398ea872751f..fe9181533de3 100644
--- a/drivers/net/wireless/ath/ath9k/dynack.c
+++ b/drivers/net/wireless/ath/ath9k/dynack.c
@@ -20,11 +20,30 @@

#define COMPUTE_TO (5 * HZ)
#define LATEACK_DELAY (10 * HZ)
-#define LATEACK_TO 256
-#define MAX_DELAY 300
#define EWMA_LEVEL 96
#define EWMA_DIV 128

+/**
+ * ath_dynack_get_max_to - set max timeout according to channel width
+ * @ah: ath hw
+ *
+ */
+static u32 ath_dynack_get_max_to(struct ath_hw *ah)
+{
+ const struct ath9k_channel *chan = ah->curchan;
+
+ if (!chan)
+ return 300;
+
+ if (IS_CHAN_HT40(chan))
+ return 300;
+ if (IS_CHAN_HALF_RATE(chan))
+ return 750;
+ if (IS_CHAN_QUARTER_RATE(chan))
+ return 1500;
+ return 600;
+}
+
/**
* ath_dynack_ewma - EWMA (Exponentially Weighted Moving Average) calculation
*
@@ -126,15 +145,16 @@ static void ath_dynack_compute_ackto(struct ath_hw *ah)
*/
static void ath_dynack_compute_to(struct ath_hw *ah)
{
- u32 ackto, ack_ts;
- u8 *dst, *src;
+ struct ath_dynack *da = &ah->dynack;
+ u32 ackto, ack_ts, max_to;
struct ieee80211_sta *sta;
- struct ath_node *an;
struct ts_info *st_ts;
- struct ath_dynack *da = &ah->dynack;
+ struct ath_node *an;
+ u8 *dst, *src;

rcu_read_lock();

+ max_to = ath_dynack_get_max_to(ah);
while (da->st_rbf.h_rb != da->st_rbf.t_rb &&
da->ack_rbf.h_rb != da->ack_rbf.t_rb) {
ack_ts = da->ack_rbf.tstamp[da->ack_rbf.h_rb];
@@ -150,7 +170,7 @@ static void ath_dynack_compute_to(struct ath_hw *ah)
if (ack_ts > st_ts->tstamp + st_ts->dur) {
ackto = ack_ts - st_ts->tstamp - st_ts->dur;

- if (ackto < MAX_DELAY) {
+ if (ackto < max_to) {
sta = ieee80211_find_sta_by_ifaddr(ah->hw, dst,
src);
if (sta) {
@@ -207,8 +227,10 @@ void ath_dynack_sample_tx_ts(struct ath_hw *ah, struct sk_buff *skb,
if (ieee80211_is_assoc_req(hdr->frame_control) ||
ieee80211_is_assoc_resp(hdr->frame_control) ||
ieee80211_is_auth(hdr->frame_control)) {
+ u32 max_to = ath_dynack_get_max_to(ah);
+
ath_dbg(common, DYNACK, "late ack\n");
- ath_dynack_set_timeout(ah, LATEACK_TO);
+ ath_dynack_set_timeout(ah, max_to);
if (sta) {
struct ath_node *an;

--
2.17.1

78 changes: 78 additions & 0 deletions ...ernel/mac80211/patches/ath/561-ath9k-dynack-set-ackto-to-max-timeout-in-ath_dynack_.patch
View file
@@ -0,0 +1,78 @@
From cc783bfa67e87d2e6206f7626b7bbb74d5c5f269 Mon Sep 17 00:00:00 2001
From: Lorenzo Bianconi <lorenzo@kernel.org>
Date: Tue, 20 Aug 2019 18:20:22 +0200
Subject: [PATCH 4/4] ath9k: dynack: set ackto to max timeout in
ath_dynack_reset

Initialize acktimeout to the maximum configurable value in
ath_dynack_reset in order to not disconnect long distance static links
enabling dynack and even to take care of possible errors configuring
a static timeout. Moreover initialize station timeout value to the current
acktimeout value

Tested-by: Koen Vandeputte <koen.vandeputte@ncentric.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
drivers/net/wireless/ath/ath9k/dynack.c | 20 +++++++++++++-------
1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/dynack.c b/drivers/net/wireless/ath/ath9k/dynack.c
index fe9181533de3..f786be04d0ac 100644
--- a/drivers/net/wireless/ath/ath9k/dynack.c
+++ b/drivers/net/wireless/ath/ath9k/dynack.c
@@ -321,11 +321,9 @@ EXPORT_SYMBOL(ath_dynack_sample_ack_ts);
*/
void ath_dynack_node_init(struct ath_hw *ah, struct ath_node *an)
{
- /* ackto = slottime + sifs + air delay */
- u32 ackto = 9 + 16 + 64;
struct ath_dynack *da = &ah->dynack;

- an->ackto = ackto;
+ an->ackto = da->ackto;

spin_lock(&da->qlock);
list_add_tail(&an->list, &da->nodes);
@@ -356,20 +354,26 @@ EXPORT_SYMBOL(ath_dynack_node_deinit);
*/
void ath_dynack_reset(struct ath_hw *ah)
{
- /* ackto = slottime + sifs + air delay */
- u32 ackto = 9 + 16 + 64;
struct ath_dynack *da = &ah->dynack;
+ struct ath_node *an;
+
+ spin_lock_bh(&da->qlock);

da->lto = jiffies + COMPUTE_TO;
- da->ackto = ackto;

da->st_rbf.t_rb = 0;
da->st_rbf.h_rb = 0;
da->ack_rbf.t_rb = 0;
da->ack_rbf.h_rb = 0;

+ da->ackto = ath_dynack_get_max_to(ah);
+ list_for_each_entry(an, &da->nodes, list)
+ an->ackto = da->ackto;
+
/* init acktimeout */
- ath_dynack_set_timeout(ah, ackto);
+ ath_dynack_set_timeout(ah, da->ackto);
+
+ spin_unlock_bh(&da->qlock);
}
EXPORT_SYMBOL(ath_dynack_reset);

@@ -386,6 +390,8 @@ void ath_dynack_init(struct ath_hw *ah)

spin_lock_init(&da->qlock);
INIT_LIST_HEAD(&da->nodes);
+ /* ackto = slottime + sifs + air delay */
+ da->ackto = 9 + 16 + 64;

ah->hw->wiphy->features |= NL80211_FEATURE_ACKTO_ESTIMATION;
}
--
2.17.1

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