Remove deferred sampling code which does not work well with rate tables + probing. Fix tx status handling if the first invalid rate idx is not set to -1 Signed-off-by: Felix Fietkau <nbd@nbd.name>
		
			
				
	
	
		
			97 lines
		
	
	
		
			3.2 KiB
		
	
	
	
		
			Diff
		
	
	
	
	
	
			
		
		
	
	
			97 lines
		
	
	
		
			3.2 KiB
		
	
	
	
		
			Diff
		
	
	
	
	
	
From: Felix Fietkau <nbd@nbd.name>
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Date: Wed, 11 Nov 2020 19:17:44 +0100
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Subject: [PATCH] mac80211: minstrel: remove deferred sampling code
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Deferring sampling attempts to the second stage has some bad interactions
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with drivers that process the rate table in hardware and use the probe flag
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to indicate probing packets (e.g. most mt76 drivers). On affected drivers
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it can lead to probing not working at all.
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If the link conditions turn worse, it might not be such a good idea to
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do a lot of sampling for lower rates in this case.
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Fix this by simply skipping the sample attempt instead of deferring it,
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but keep the checks that would allow it to be sampled if it was skipped
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too often, but only if it has less than 95% success probability.
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Also ensure that IEEE80211_TX_CTL_RATE_CTRL_PROBE is set for all probing
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packets.
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Cc: stable@vger.kernel.org
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Fixes: cccf129f820e ("mac80211: add the 'minstrel' rate control algorithm")
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Signed-off-by: Felix Fietkau <nbd@nbd.name>
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---
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--- a/net/mac80211/rc80211_minstrel.c
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+++ b/net/mac80211/rc80211_minstrel.c
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@@ -287,12 +287,6 @@ minstrel_tx_status(void *priv, struct ie
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 			mi->r[ndx].stats.success += success;
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 	}
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-	if ((info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) && (i >= 0))
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-		mi->sample_packets++;
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-
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-	if (mi->sample_deferred > 0)
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-		mi->sample_deferred--;
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-
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 	if (time_after(jiffies, mi->last_stats_update +
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 				mp->update_interval / (mp->new_avg ? 2 : 1)))
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 		minstrel_update_stats(mp, mi);
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@@ -367,7 +361,7 @@ minstrel_get_rate(void *priv, struct iee
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 		return;
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 	delta = (mi->total_packets * sampling_ratio / 100) -
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-			(mi->sample_packets + mi->sample_deferred / 2);
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+			mi->sample_packets;
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 	/* delta < 0: no sampling required */
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 	prev_sample = mi->prev_sample;
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@@ -376,7 +370,6 @@ minstrel_get_rate(void *priv, struct iee
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 		return;
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 	if (mi->total_packets >= 10000) {
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-		mi->sample_deferred = 0;
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 		mi->sample_packets = 0;
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 		mi->total_packets = 0;
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 	} else if (delta > mi->n_rates * 2) {
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@@ -401,19 +394,8 @@ minstrel_get_rate(void *priv, struct iee
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 	 * rate sampling method should be used.
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 	 * Respect such rates that are not sampled for 20 interations.
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 	 */
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-	if (mrr_capable &&
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-	    msr->perfect_tx_time > mr->perfect_tx_time &&
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-	    msr->stats.sample_skipped < 20) {
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-		/* Only use IEEE80211_TX_CTL_RATE_CTRL_PROBE to mark
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-		 * packets that have the sampling rate deferred to the
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-		 * second MRR stage. Increase the sample counter only
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-		 * if the deferred sample rate was actually used.
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-		 * Use the sample_deferred counter to make sure that
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-		 * the sampling is not done in large bursts */
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-		info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
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-		rate++;
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-		mi->sample_deferred++;
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-	} else {
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+	if (msr->perfect_tx_time < mr->perfect_tx_time ||
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+	    msr->stats.sample_skipped >= 20) {
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 		if (!msr->sample_limit)
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 			return;
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@@ -433,6 +415,7 @@ minstrel_get_rate(void *priv, struct iee
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 	rate->idx = mi->r[ndx].rix;
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 	rate->count = minstrel_get_retry_count(&mi->r[ndx], info);
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+	info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
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 }
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--- a/net/mac80211/rc80211_minstrel.h
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+++ b/net/mac80211/rc80211_minstrel.h
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@@ -126,7 +126,6 @@ struct minstrel_sta_info {
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 	u8 max_prob_rate;
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 	unsigned int total_packets;
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 	unsigned int sample_packets;
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-	int sample_deferred;
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 	unsigned int sample_row;
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 	unsigned int sample_column;
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