Calling mod_timer from the rx/tx hotpath is somewhat expensive, and the
timeout doesn't need to be so precise.
Switch to a different strategy: Schedule the timer initially, store jiffies
of all last rx/tx activity which would previously modify the timer, and
let the timer re-arm itself after checking the last rx/tx timestamp.
This visibly reduces CPU load under high network load on small embedded
systems.
Signed-off-by: Felix Fietkau <nbd@xxxxxxxxxxx>
---
net/mac80211/agg-rx.c | 16 +++++++++++++++-
net/mac80211/agg-tx.c | 16 +++++++++++++++-
net/mac80211/ieee80211_i.h | 3 ++-
net/mac80211/rx.c | 3 +--
net/mac80211/sta_info.h | 4 ++++
net/mac80211/tx.c | 3 +--
6 files changed, 38 insertions(+), 7 deletions(-)
diff --git a/net/mac80211/agg-rx.c b/net/mac80211/agg-rx.c
index 1068f66..d92b345 100644
--- a/net/mac80211/agg-rx.c
+++ b/net/mac80211/agg-rx.c
@@ -141,6 +141,18 @@ static void sta_rx_agg_session_timer_expired(unsigned long data)
u8 *timer_to_id = ptid - *ptid;
struct sta_info *sta = container_of(timer_to_id, struct sta_info,
timer_to_tid[0]);
+ struct tid_ampdu_rx *tid_rx;
+ unsigned long timeout;
+
+ tid_rx = rcu_dereference(sta->ampdu_mlme.tid_rx[*ptid]);
+ if (!tid_rx)
+ return;
+
+ timeout = tid_rx->last_rx + TU_TO_JIFFIES(tid_rx->timeout);
+ if (time_is_after_jiffies(timeout)) {
+ mod_timer(&tid_rx->session_timer, timeout);
+ return;
+ }
#ifdef CONFIG_MAC80211_HT_DEBUG
printk(KERN_DEBUG "rx session timer expired on tid %d\n", (u16)*ptid);
@@ -334,8 +346,10 @@ void ieee80211_process_addba_request(struct ieee80211_local *local,
/* activate it for RX */
rcu_assign_pointer(sta->ampdu_mlme.tid_rx[tid], tid_agg_rx);
- if (timeout)
+ if (timeout) {
mod_timer(&tid_agg_rx->session_timer, TU_TO_EXP_TIME(timeout));
+ tid_agg_rx->last_rx = jiffies;
+ }
end:
mutex_unlock(&sta->ampdu_mlme.mtx);
diff --git a/net/mac80211/agg-tx.c b/net/mac80211/agg-tx.c
index 76be617..16632fa 100644
--- a/net/mac80211/agg-tx.c
+++ b/net/mac80211/agg-tx.c
@@ -417,6 +417,18 @@ static void sta_tx_agg_session_timer_expired(unsigned long data)
u8 *timer_to_id = ptid - *ptid;
struct sta_info *sta = container_of(timer_to_id, struct sta_info,
timer_to_tid[0]);
+ struct tid_ampdu_tx *tid_tx;
+ unsigned long timeout;
+
+ tid_tx = rcu_dereference_protected_tid_tx(sta, *ptid);
+ if (!tid_tx)
+ return;
+
+ timeout = tid_tx->last_tx + TU_TO_JIFFIES(tid_tx->timeout);
+ if (time_is_after_jiffies(timeout)) {
+ mod_timer(&tid_tx->session_timer, timeout);
+ return;
+ }
#ifdef CONFIG_MAC80211_HT_DEBUG
printk(KERN_DEBUG "tx session timer expired on tid %d\n", (u16)*ptid);
@@ -884,9 +896,11 @@ void ieee80211_process_addba_resp(struct ieee80211_local *local,
sta->ampdu_mlme.addba_req_num[tid] = 0;
- if (tid_tx->timeout)
+ if (tid_tx->timeout) {
mod_timer(&tid_tx->session_timer,
TU_TO_EXP_TIME(tid_tx->timeout));
+ tid_tx->last_tx = jiffies;
+ }
} else {
___ieee80211_stop_tx_ba_session(sta, tid, WLAN_BACK_INITIATOR,
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index d9798a3..2785976 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -52,7 +52,8 @@ struct ieee80211_local;
* increased memory use (about 2 kB of RAM per entry). */
#define IEEE80211_FRAGMENT_MAX 4
-#define TU_TO_EXP_TIME(x) (jiffies + usecs_to_jiffies((x) * 1024))
+#define TU_TO_JIFFIES(x) (usecs_to_jiffies((x) * 1024))
+#define TU_TO_EXP_TIME(x) (jiffies + TU_TO_JIFFIES(x))
#define IEEE80211_DEFAULT_UAPSD_QUEUES \
(IEEE80211_WMM_IE_STA_QOSINFO_AC_BK | \
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index bcfe8c7..8da3b36 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -793,8 +793,7 @@ static void ieee80211_rx_reorder_ampdu(struct ieee80211_rx_data *rx)
/* reset session timer */
if (tid_agg_rx->timeout)
- mod_timer(&tid_agg_rx->session_timer,
- TU_TO_EXP_TIME(tid_agg_rx->timeout));
+ tid_agg_rx->last_rx = jiffies;
/* if this mpdu is fragmented - terminate rx aggregation session */
sc = le16_to_cpu(hdr->seq_ctrl);
diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index ab05768..e21652b 100644
--- a/net/mac80211/sta_info.h
+++ b/net/mac80211/sta_info.h
@@ -101,6 +101,7 @@ enum ieee80211_sta_info_flags {
* @dialog_token: dialog token for aggregation session
* @timeout: session timeout value to be filled in ADDBA requests
* @state: session state (see above)
+ * @last_tx: jiffies of last tx activity
* @stop_initiator: initiator of a session stop
* @tx_stop: TX DelBA frame when stopping
* @buf_size: reorder buffer size at receiver
@@ -122,6 +123,7 @@ struct tid_ampdu_tx {
struct timer_list addba_resp_timer;
struct sk_buff_head pending;
unsigned long state;
+ unsigned long last_tx;
u16 timeout;
u8 dialog_token;
u8 stop_initiator;
@@ -139,6 +141,7 @@ struct tid_ampdu_tx {
* @reorder_time: jiffies when skb was added
* @session_timer: check if peer keeps Tx-ing on the TID (by timeout value)
* @reorder_timer: releases expired frames from the reorder buffer.
+ * @last_rx: jiffies of last rx activity
* @head_seq_num: head sequence number in reordering buffer.
* @stored_mpdu_num: number of MPDUs in reordering buffer
* @ssn: Starting Sequence Number expected to be aggregated.
@@ -163,6 +166,7 @@ struct tid_ampdu_rx {
unsigned long *reorder_time;
struct timer_list session_timer;
struct timer_list reorder_timer;
+ unsigned long last_rx;
u16 head_seq_num;
u16 stored_mpdu_num;
u16 ssn;
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 782a601..5ad2c40 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -1118,8 +1118,7 @@ static bool ieee80211_tx_prep_agg(struct ieee80211_tx_data *tx,
/* reset session timer */
if (reset_agg_timer && tid_tx->timeout)
- mod_timer(&tid_tx->session_timer,
- TU_TO_EXP_TIME(tid_tx->timeout));
+ tid_tx->last_tx = jiffies;
return queued;
}
--
1.7.3.2
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