From 12d3952fc4a1cd96234bc7023bf7eefeb0bb6355 Mon Sep 17 00:00:00 2001 From: Felix Fietkau Date: Sun, 18 Mar 2012 22:58:06 +0100 Subject: [PATCH] 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 Signed-off-by: John W. Linville --- net/mac80211/agg-rx.c | 18 ++++++++++++++++-- net/mac80211/agg-tx.c | 18 ++++++++++++++++-- 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, 40 insertions(+), 9 deletions(-) diff --git a/net/mac80211/agg-rx.c b/net/mac80211/agg-rx.c index 64d3ce5..a070d4f 100644 --- a/net/mac80211/agg-rx.c +++ b/net/mac80211/agg-rx.c @@ -142,6 +142,18 @@ 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); @@ -291,7 +303,7 @@ void ieee80211_process_addba_request(struct ieee80211_local *local, /* rx timer */ tid_agg_rx->session_timer.function = sta_rx_agg_session_timer_expired; tid_agg_rx->session_timer.data = (unsigned long)&sta->timer_to_tid[tid]; - init_timer(&tid_agg_rx->session_timer); + init_timer_deferrable(&tid_agg_rx->session_timer); /* rx reorder timer */ tid_agg_rx->reorder_timer.function = sta_rx_agg_reorder_timer_expired; @@ -335,8 +347,10 @@ 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..9628a18 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); @@ -542,7 +554,7 @@ int ieee80211_start_tx_ba_session(struct ieee80211_sta *pubsta, u16 tid, /* tx timer */ tid_tx->session_timer.function = sta_tx_agg_session_timer_expired; tid_tx->session_timer.data = (unsigned long)&sta->timer_to_tid[tid]; - init_timer(&tid_tx->session_timer); + init_timer_deferrable(&tid_tx->session_timer); /* assign a dialog token */ sta->ampdu_mlme.dialog_token_allocator++; @@ -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 0ae822c..23765e3 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 a9b2727..da2447a 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; } -- 2.7.4