ath9k: improve tx scheduling fairness

Instead of trying to schedule the same TID multiple times in a loop,
iterate over other TIDs/stations first.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
index 3b66f2b67fecbfaabed4562fa57646e53d866e29..f9e6eb2a4e0b30e653b13647e3689fb5576c2c2b 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -1345,8 +1345,8 @@ ath_tx_form_burst(struct ath_softc *sc, struct ath_txq *txq,
        } while (1);
 }
 
-static void ath_tx_sched_aggr(struct ath_softc *sc, struct ath_txq *txq,
-                             struct ath_atx_tid *tid)
+static bool ath_tx_sched_aggr(struct ath_softc *sc, struct ath_txq *txq,
+                             struct ath_atx_tid *tid, bool *stop)
 {
        struct ath_buf *bf;
        struct ieee80211_tx_info *tx_info;
@@ -1355,40 +1355,41 @@ static void ath_tx_sched_aggr(struct ath_softc *sc, struct ath_txq *txq,
        int aggr_len = 0;
        bool aggr, last = true;
 
-       do {
-               if (!ath_tid_has_buffered(tid))
-                       return;
+       if (!ath_tid_has_buffered(tid))
+               return false;
 
-               INIT_LIST_HEAD(&bf_q);
+       INIT_LIST_HEAD(&bf_q);
 
-               bf = ath_tx_get_tid_subframe(sc, txq, tid, &tid_q);
-               if (!bf)
-                       break;
+       bf = ath_tx_get_tid_subframe(sc, txq, tid, &tid_q);
+       if (!bf)
+               return false;
 
-               tx_info = IEEE80211_SKB_CB(bf->bf_mpdu);
-               aggr = !!(tx_info->flags & IEEE80211_TX_CTL_AMPDU);
-               if ((aggr && txq->axq_ampdu_depth >= ATH_AGGR_MIN_QDEPTH) ||
-                   (!aggr && txq->axq_depth >= ATH_NON_AGGR_MIN_QDEPTH))
-                       break;
+       tx_info = IEEE80211_SKB_CB(bf->bf_mpdu);
+       aggr = !!(tx_info->flags & IEEE80211_TX_CTL_AMPDU);
+       if ((aggr && txq->axq_ampdu_depth >= ATH_AGGR_MIN_QDEPTH) ||
+               (!aggr && txq->axq_depth >= ATH_NON_AGGR_MIN_QDEPTH)) {
+               *stop = true;
+               return false;
+       }
 
-               ath_set_rates(tid->an->vif, tid->an->sta, bf);
-               if (aggr)
-                       last = ath_tx_form_aggr(sc, txq, tid, &bf_q, bf,
-                                               tid_q, &aggr_len);
-               else
-                       ath_tx_form_burst(sc, txq, tid, &bf_q, bf, tid_q);
+       ath_set_rates(tid->an->vif, tid->an->sta, bf);
+       if (aggr)
+               last = ath_tx_form_aggr(sc, txq, tid, &bf_q, bf,
+                                       tid_q, &aggr_len);
+       else
+               ath_tx_form_burst(sc, txq, tid, &bf_q, bf, tid_q);
 
-               if (list_empty(&bf_q))
-                       return;
+       if (list_empty(&bf_q))
+               return false;
 
-               if (tid->ac->clear_ps_filter) {
-                       tid->ac->clear_ps_filter = false;
-                       tx_info->flags |= IEEE80211_TX_CTL_CLEAR_PS_FILT;
-               }
+       if (tid->ac->clear_ps_filter) {
+               tid->ac->clear_ps_filter = false;
+               tx_info->flags |= IEEE80211_TX_CTL_CLEAR_PS_FILT;
+       }
 
-               ath_tx_fill_desc(sc, bf, txq, aggr_len);
-               ath_tx_txqaddbuf(sc, txq, &bf_q, false);
-       } while (!last);
+       ath_tx_fill_desc(sc, bf, txq, aggr_len);
+       ath_tx_txqaddbuf(sc, txq, &bf_q, false);
+       return true;
 }
 
 int ath_tx_aggr_start(struct ath_softc *sc, struct ieee80211_sta *sta,
@@ -1824,25 +1825,27 @@ void ath_tx_cleanupq(struct ath_softc *sc, struct ath_txq *txq)
  */
 void ath_txq_schedule(struct ath_softc *sc, struct ath_txq *txq)
 {
-       struct ath_atx_ac *ac, *ac_tmp, *last_ac;
+       struct ath_atx_ac *ac, *last_ac;
        struct ath_atx_tid *tid, *last_tid;
+       bool sent = false;
 
        if (test_bit(SC_OP_HW_RESET, &sc->sc_flags) ||
-           list_empty(&txq->axq_acq) ||
-           txq->axq_ampdu_depth >= ATH_AGGR_MIN_QDEPTH)
+           list_empty(&txq->axq_acq))
                return;
 
        rcu_read_lock();
 
-       ac = list_first_entry(&txq->axq_acq, struct ath_atx_ac, list);
        last_ac = list_entry(txq->axq_acq.prev, struct ath_atx_ac, list);
+       while (!list_empty(&txq->axq_acq)) {
+               bool stop = false;
 
-       list_for_each_entry_safe(ac, ac_tmp, &txq->axq_acq, list) {
+               ac = list_first_entry(&txq->axq_acq, struct ath_atx_ac, list);
                last_tid = list_entry(ac->tid_q.prev, struct ath_atx_tid, list);
                list_del(&ac->list);
                ac->sched = false;
 
                while (!list_empty(&ac->tid_q)) {
+
                        tid = list_first_entry(&ac->tid_q, struct ath_atx_tid,
                                               list);
                        list_del(&tid->list);
@@ -1851,7 +1854,8 @@ void ath_txq_schedule(struct ath_softc *sc, struct ath_txq *txq)
                        if (tid->paused)
                                continue;
 
-                       ath_tx_sched_aggr(sc, txq, tid);
+                       if (ath_tx_sched_aggr(sc, txq, tid, &stop))
+                               sent = true;
 
                        /*
                         * add tid to round-robin queue if more frames
@@ -1860,8 +1864,7 @@ void ath_txq_schedule(struct ath_softc *sc, struct ath_txq *txq)
                        if (ath_tid_has_buffered(tid))
                                ath_tx_queue_tid(txq, tid);
 
-                       if (tid == last_tid ||
-                           txq->axq_ampdu_depth >= ATH_AGGR_MIN_QDEPTH)
+                       if (stop || tid == last_tid)
                                break;
                }
 
@@ -1870,9 +1873,17 @@ void ath_txq_schedule(struct ath_softc *sc, struct ath_txq *txq)
                        list_add_tail(&ac->list, &txq->axq_acq);
                }
 
-               if (ac == last_ac ||
-                   txq->axq_ampdu_depth >= ATH_AGGR_MIN_QDEPTH)
+               if (stop)
                        break;
+
+               if (ac == last_ac) {
+                       if (!sent)
+                               break;
+
+                       sent = false;
+                       last_ac = list_entry(txq->axq_acq.prev,
+                                            struct ath_atx_ac, list);
+               }
        }
 
        rcu_read_unlock();