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mac80211: minstrel_ht: set A-MSDU tx limits based on selected max_prob_rate

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

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Felix Fietkau 2016-03-03 22:59:01 +01:00 committed by Johannes Berg
parent 6e0456b545
commit 918fe04b28
1 changed files with 54 additions and 0 deletions
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54
net/mac80211/rc80211_minstrel_ht.c
View file

@ -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);
}