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Commit 918fe04b authored by Felix Fietkau's avatar Felix Fietkau Committed by Johannes Berg
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mac80211: minstrel_ht: set A-MSDU tx limits based on selected max_prob_rate 



Prevents excessive A-MSDU aggregation at low data rates or bad
conditions.

Signed-off-by: default avatarFelix Fietkau <nbd@openwrt.org>
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent 6e0456b5

net/mac80211/rc80211_minstrel_ht.c

+54 −0
Original line number Diff line number Diff line
@@ -883,6 +883,59 @@ minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi, 
	ratetbl->rate[offset].flags = flags;

}



static inline int

minstrel_ht_get_prob_ewma(struct minstrel_ht_sta *mi, int rate)

{

	int group = rate / MCS_GROUP_RATES;

	rate %= MCS_GROUP_RATES;

	return mi->groups[group].rates[rate].prob_ewma;

}



static int

minstrel_ht_get_max_amsdu_len(struct minstrel_ht_sta *mi)

{

	int group = mi->max_prob_rate / MCS_GROUP_RATES;

	const struct mcs_group *g = &minstrel_mcs_groups[group];

	int rate = mi->max_prob_rate % MCS_GROUP_RATES;



	/* Disable A-MSDU if max_prob_rate is bad */

	if (mi->groups[group].rates[rate].prob_ewma < MINSTREL_FRAC(50, 100))

		return 1;



	/* If the rate is slower than single-stream MCS1, make A-MSDU limit small */

	if (g->duration[rate] > MCS_DURATION(1, 0, 52))

		return 500;



	/*

	 * If the rate is slower than single-stream MCS4, limit A-MSDU to usual

	 * data packet size

	 */

	if (g->duration[rate] > MCS_DURATION(1, 0, 104))

		return 1600;



	/*

	 * If the rate is slower than single-stream MCS7, or if the max throughput

	 * rate success probability is less than 75%, limit A-MSDU to twice the usual

	 * data packet size

	 */

	if (g->duration[rate] > MCS_DURATION(1, 0, 260) ||

	    (minstrel_ht_get_prob_ewma(mi, mi->max_tp_rate[0]) <

	     MINSTREL_FRAC(75, 100)))

		return 3200;



	/*

	 * HT A-MPDU limits maximum MPDU size under BA agreement to 4095 bytes.

	 * Since aggregation sessions are started/stopped without txq flush, use

	 * the limit here to avoid the complexity of having to de-aggregate

	 * packets in the queue.

	 */

	if (!mi->sta->vht_cap.vht_supported)

		return IEEE80211_MAX_MPDU_LEN_HT_BA;



	/* unlimited */

	return 0;

}



static void

minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)

{
@@ -907,6 +960,7 @@ minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi) 
		minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_prob_rate);

	}



	mi->sta->max_rc_amsdu_len = minstrel_ht_get_max_amsdu_len(mi);

	rates->rate[i].idx = -1;

	rate_control_set_rates(mp->hw, mi->sta, rates);

}