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/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 0ae822c..23765e3 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -52,7 +52,8 @@
* 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 | \