mac80211: optimize aggregation session timeout handling
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.
Make the session timers deferrable to avoid causing extra wakeups on systems
running on battery.
This visibly reduces CPU load under high network load on small embedded
systems.
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
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 @@
* @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 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 @@
* @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 @@
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;