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1 files changed, 477 insertions, 0 deletions

diff --git a/net/mac80211/rc80211_pid_algo.c b/net/mac80211/rc80211_pid_algo.c
new file mode 100644
index 0000000..5134907
--- /dev/null
+++ b/net/mac80211/rc80211_pid_algo.c
@@ -0,0 +1,477 @@
+/*
+ * Copyright 2002-2005, Instant802 Networks, Inc.
+ * Copyright 2005, Devicescape Software, Inc.
+ * Copyright 2007, Mattias Nissler <mattias.nissler@gmx.de>
+ * Copyright 2007-2008, Stefano Brivio <stefano.brivio@polimi.it>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/netdevice.h>
+#include <linux/types.h>
+#include <linux/skbuff.h>
+#include <linux/debugfs.h>
+#include <linux/slab.h>
+#include <net/mac80211.h>
+#include "rate.h"
+#include "mesh.h"
+#include "rc80211_pid.h"
+
+
+/* This is an implementation of a TX rate control algorithm that uses a PID
+ * controller. Given a target failed frames rate, the controller decides about
+ * TX rate changes to meet the target failed frames rate.
+ *
+ * The controller basically computes the following:
+ *
+ * adj = CP * err + CI * err_avg + CD * (err - last_err) * (1 + sharpening)
+ *
+ * where
+ * 	adj	adjustment value that is used to switch TX rate (see below)
+ * 	err	current error: target vs. current failed frames percentage
+ * 	last_err	last error
+ * 	err_avg	average (i.e. poor man's integral) of recent errors
+ *	sharpening	non-zero when fast response is needed (i.e. right after
+ *			association or no frames sent for a long time), heading
+ * 			to zero over time
+ * 	CP	Proportional coefficient
+ * 	CI	Integral coefficient
+ * 	CD	Derivative coefficient
+ *
+ * CP, CI, CD are subject to careful tuning.
+ *
+ * The integral component uses a exponential moving average approach instead of
+ * an actual sliding window. The advantage is that we don't need to keep an
+ * array of the last N error values and computation is easier.
+ *
+ * Once we have the adj value, we map it to a rate by means of a learning
+ * algorithm. This algorithm keeps the state of the percentual failed frames
+ * difference between rates. The behaviour of the lowest available rate is kept
+ * as a reference value, and every time we switch between two rates, we compute
+ * the difference between the failed frames each rate exhibited. By doing so,
+ * we compare behaviours which different rates exhibited in adjacent timeslices,
+ * thus the comparison is minimally affected by external conditions. This
+ * difference gets propagated to the whole set of measurements, so that the
+ * reference is always the same. Periodically, we normalize this set so that
+ * recent events weigh the most. By comparing the adj value with this set, we
+ * avoid pejorative switches to lower rates and allow for switches to higher
+ * rates if they behaved well.
+ *
+ * Note that for the computations we use a fixed-point representation to avoid
+ * floating point arithmetic. Hence, all values are shifted left by
+ * RC_PID_ARITH_SHIFT.
+ */
+
+
+/* Adjust the rate while ensuring that we won't switch to a lower rate if it
+ * exhibited a worse failed frames behaviour and we'll choose the highest rate
+ * whose failed frames behaviour is not worse than the one of the original rate
+ * target. While at it, check that the new rate is valid. */
+static void rate_control_pid_adjust_rate(struct ieee80211_supported_band *sband,
+					 struct ieee80211_sta *sta,
+					 struct rc_pid_sta_info *spinfo, int adj,
+					 struct rc_pid_rateinfo *rinfo)
+{
+	int cur_sorted, new_sorted, probe, tmp, n_bitrates, band;
+	int cur = spinfo->txrate_idx;
+
+	band = sband->band;
+	n_bitrates = sband->n_bitrates;
+
+	/* Map passed arguments to sorted values. */
+	cur_sorted = rinfo[cur].rev_index;
+	new_sorted = cur_sorted + adj;
+
+	/* Check limits. */
+	if (new_sorted < 0)
+		new_sorted = rinfo[0].rev_index;
+	else if (new_sorted >= n_bitrates)
+		new_sorted = rinfo[n_bitrates - 1].rev_index;
+
+	tmp = new_sorted;
+
+	if (adj < 0) {
+		/* Ensure that the rate decrease isn't disadvantageous. */
+		for (probe = cur_sorted; probe >= new_sorted; probe--)
+			if (rinfo[probe].diff <= rinfo[cur_sorted].diff &&
+			    rate_supported(sta, band, rinfo[probe].index))
+				tmp = probe;
+	} else {
+		/* Look for rate increase with zero (or below) cost. */
+		for (probe = new_sorted + 1; probe < n_bitrates; probe++)
+			if (rinfo[probe].diff <= rinfo[new_sorted].diff &&
+			    rate_supported(sta, band, rinfo[probe].index))
+				tmp = probe;
+	}
+
+	/* Fit the rate found to the nearest supported rate. */
+	do {
+		if (rate_supported(sta, band, rinfo[tmp].index)) {
+			spinfo->txrate_idx = rinfo[tmp].index;
+			break;
+		}
+		if (adj < 0)
+			tmp--;
+		else
+			tmp++;
+	} while (tmp < n_bitrates && tmp >= 0);
+
+#ifdef CPTCFG_MAC80211_DEBUGFS
+	rate_control_pid_event_rate_change(&spinfo->events,
+		spinfo->txrate_idx,
+		sband->bitrates[spinfo->txrate_idx].bitrate);
+#endif
+}
+
+/* Normalize the failed frames per-rate differences. */
+static void rate_control_pid_normalize(struct rc_pid_info *pinfo, int l)
+{
+	int i, norm_offset = pinfo->norm_offset;
+	struct rc_pid_rateinfo *r = pinfo->rinfo;
+
+	if (r[0].diff > norm_offset)
+		r[0].diff -= norm_offset;
+	else if (r[0].diff < -norm_offset)
+		r[0].diff += norm_offset;
+	for (i = 0; i < l - 1; i++)
+		if (r[i + 1].diff > r[i].diff + norm_offset)
+			r[i + 1].diff -= norm_offset;
+		else if (r[i + 1].diff <= r[i].diff)
+			r[i + 1].diff += norm_offset;
+}
+
+static void rate_control_pid_sample(struct rc_pid_info *pinfo,
+				    struct ieee80211_supported_band *sband,
+				    struct ieee80211_sta *sta,
+				    struct rc_pid_sta_info *spinfo)
+{
+	struct rc_pid_rateinfo *rinfo = pinfo->rinfo;
+	u32 pf;
+	s32 err_avg;
+	u32 err_prop;
+	u32 err_int;
+	u32 err_der;
+	int adj, i, j, tmp;
+	unsigned long period;
+
+	/* In case nothing happened during the previous control interval, turn
+	 * the sharpening factor on. */
+	period = msecs_to_jiffies(pinfo->sampling_period);
+	if (jiffies - spinfo->last_sample > 2 * period)
+		spinfo->sharp_cnt = pinfo->sharpen_duration;
+
+	spinfo->last_sample = jiffies;
+
+	/* This should never happen, but in case, we assume the old sample is
+	 * still a good measurement and copy it. */
+	if (unlikely(spinfo->tx_num_xmit == 0))
+		pf = spinfo->last_pf;
+	else
+		pf = spinfo->tx_num_failed * 100 / spinfo->tx_num_xmit;
+
+	spinfo->tx_num_xmit = 0;
+	spinfo->tx_num_failed = 0;
+
+	/* If we just switched rate, update the rate behaviour info. */
+	if (pinfo->oldrate != spinfo->txrate_idx) {
+
+		i = rinfo[pinfo->oldrate].rev_index;
+		j = rinfo[spinfo->txrate_idx].rev_index;
+
+		tmp = (pf - spinfo->last_pf);
+		tmp = RC_PID_DO_ARITH_RIGHT_SHIFT(tmp, RC_PID_ARITH_SHIFT);
+
+		rinfo[j].diff = rinfo[i].diff + tmp;
+		pinfo->oldrate = spinfo->txrate_idx;
+	}
+	rate_control_pid_normalize(pinfo, sband->n_bitrates);
+
+	/* Compute the proportional, integral and derivative errors. */
+	err_prop = (pinfo->target - pf) << RC_PID_ARITH_SHIFT;
+
+	err_avg = spinfo->err_avg_sc >> pinfo->smoothing_shift;
+	spinfo->err_avg_sc = spinfo->err_avg_sc - err_avg + err_prop;
+	err_int = spinfo->err_avg_sc >> pinfo->smoothing_shift;
+
+	err_der = (pf - spinfo->last_pf) *
+		  (1 + pinfo->sharpen_factor * spinfo->sharp_cnt);
+	spinfo->last_pf = pf;
+	if (spinfo->sharp_cnt)
+			spinfo->sharp_cnt--;
+
+#ifdef CPTCFG_MAC80211_DEBUGFS
+	rate_control_pid_event_pf_sample(&spinfo->events, pf, err_prop, err_int,
+					 err_der);
+#endif
+
+	/* Compute the controller output. */
+	adj = (err_prop * pinfo->coeff_p + err_int * pinfo->coeff_i
+	      + err_der * pinfo->coeff_d);
+	adj = RC_PID_DO_ARITH_RIGHT_SHIFT(adj, 2 * RC_PID_ARITH_SHIFT);
+
+	/* Change rate. */
+	if (adj)
+		rate_control_pid_adjust_rate(sband, sta, spinfo, adj, rinfo);
+}
+
+static void rate_control_pid_tx_status(void *priv, struct ieee80211_supported_band *sband,
+				       struct ieee80211_sta *sta, void *priv_sta,
+				       struct sk_buff *skb)
+{
+	struct rc_pid_info *pinfo = priv;
+	struct rc_pid_sta_info *spinfo = priv_sta;
+	unsigned long period;
+	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+
+	if (!spinfo)
+		return;
+
+	/* Ignore all frames that were sent with a different rate than the rate
+	 * we currently advise mac80211 to use. */
+	if (info->status.rates[0].idx != spinfo->txrate_idx)
+		return;
+
+	spinfo->tx_num_xmit++;
+
+#ifdef CPTCFG_MAC80211_DEBUGFS
+	rate_control_pid_event_tx_status(&spinfo->events, info);
+#endif
+
+	/* We count frames that totally failed to be transmitted as two bad
+	 * frames, those that made it out but had some retries as one good and
+	 * one bad frame. */
+	if (!(info->flags & IEEE80211_TX_STAT_ACK)) {
+		spinfo->tx_num_failed += 2;
+		spinfo->tx_num_xmit++;
+	} else if (info->status.rates[0].count > 1) {
+		spinfo->tx_num_failed++;
+		spinfo->tx_num_xmit++;
+	}
+
+	/* Update PID controller state. */
+	period = msecs_to_jiffies(pinfo->sampling_period);
+	if (time_after(jiffies, spinfo->last_sample + period))
+		rate_control_pid_sample(pinfo, sband, sta, spinfo);
+}
+
+static void
+rate_control_pid_get_rate(void *priv, struct ieee80211_sta *sta,
+			  void *priv_sta,
+			  struct ieee80211_tx_rate_control *txrc)
+{
+	struct sk_buff *skb = txrc->skb;
+	struct ieee80211_supported_band *sband = txrc->sband;
+	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+	struct rc_pid_sta_info *spinfo = priv_sta;
+	int rateidx;
+
+	if (txrc->rts)
+		info->control.rates[0].count =
+			txrc->hw->conf.long_frame_max_tx_count;
+	else
+		info->control.rates[0].count =
+			txrc->hw->conf.short_frame_max_tx_count;
+
+	/* Send management frames and NO_ACK data using lowest rate. */
+	if (rate_control_send_low(sta, priv_sta, txrc))
+		return;
+
+	rateidx = spinfo->txrate_idx;
+
+	if (rateidx >= sband->n_bitrates)
+		rateidx = sband->n_bitrates - 1;
+
+	info->control.rates[0].idx = rateidx;
+
+#ifdef CPTCFG_MAC80211_DEBUGFS
+	rate_control_pid_event_tx_rate(&spinfo->events,
+		rateidx, sband->bitrates[rateidx].bitrate);
+#endif
+}
+
+static void
+rate_control_pid_rate_init(void *priv, struct ieee80211_supported_band *sband,
+			   struct ieee80211_sta *sta, void *priv_sta)
+{
+	struct rc_pid_sta_info *spinfo = priv_sta;
+	struct rc_pid_info *pinfo = priv;
+	struct rc_pid_rateinfo *rinfo = pinfo->rinfo;
+	int i, j, tmp;
+	bool s;
+
+	/* TODO: This routine should consider using RSSI from previous packets
+	 * as we need to have IEEE 802.1X auth succeed immediately after assoc..
+	 * Until that method is implemented, we will use the lowest supported
+	 * rate as a workaround. */
+
+	/* Sort the rates. This is optimized for the most common case (i.e.
+	 * almost-sorted CCK+OFDM rates). Kind of bubble-sort with reversed
+	 * mapping too. */
+	for (i = 0; i < sband->n_bitrates; i++) {
+		rinfo[i].index = i;
+		rinfo[i].rev_index = i;
+		if (RC_PID_FAST_START)
+			rinfo[i].diff = 0;
+		else
+			rinfo[i].diff = i * pinfo->norm_offset;
+	}
+	for (i = 1; i < sband->n_bitrates; i++) {
+		s = false;
+		for (j = 0; j < sband->n_bitrates - i; j++)
+			if (unlikely(sband->bitrates[rinfo[j].index].bitrate >
+				     sband->bitrates[rinfo[j + 1].index].bitrate)) {
+				tmp = rinfo[j].index;
+				rinfo[j].index = rinfo[j + 1].index;
+				rinfo[j + 1].index = tmp;
+				rinfo[rinfo[j].index].rev_index = j;
+				rinfo[rinfo[j + 1].index].rev_index = j + 1;
+				s = true;
+			}
+		if (!s)
+			break;
+	}
+
+	spinfo->txrate_idx = rate_lowest_index(sband, sta);
+}
+
+static void *rate_control_pid_alloc(struct ieee80211_hw *hw,
+				    struct dentry *debugfsdir)
+{
+	struct rc_pid_info *pinfo;
+	struct rc_pid_rateinfo *rinfo;
+	struct ieee80211_supported_band *sband;
+	int i, max_rates = 0;
+#ifdef CPTCFG_MAC80211_DEBUGFS
+	struct rc_pid_debugfs_entries *de;
+#endif
+
+	pinfo = kmalloc(sizeof(*pinfo), GFP_ATOMIC);
+	if (!pinfo)
+		return NULL;
+
+	for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
+		sband = hw->wiphy->bands[i];
+		if (sband && sband->n_bitrates > max_rates)
+			max_rates = sband->n_bitrates;
+	}
+
+	rinfo = kmalloc(sizeof(*rinfo) * max_rates, GFP_ATOMIC);
+	if (!rinfo) {
+		kfree(pinfo);
+		return NULL;
+	}
+
+	pinfo->target = RC_PID_TARGET_PF;
+	pinfo->sampling_period = RC_PID_INTERVAL;
+	pinfo->coeff_p = RC_PID_COEFF_P;
+	pinfo->coeff_i = RC_PID_COEFF_I;
+	pinfo->coeff_d = RC_PID_COEFF_D;
+	pinfo->smoothing_shift = RC_PID_SMOOTHING_SHIFT;
+	pinfo->sharpen_factor = RC_PID_SHARPENING_FACTOR;
+	pinfo->sharpen_duration = RC_PID_SHARPENING_DURATION;
+	pinfo->norm_offset = RC_PID_NORM_OFFSET;
+	pinfo->rinfo = rinfo;
+	pinfo->oldrate = 0;
+
+#ifdef CPTCFG_MAC80211_DEBUGFS
+	de = &pinfo->dentries;
+	de->target = debugfs_create_u32("target_pf", S_IRUSR | S_IWUSR,
+					debugfsdir, &pinfo->target);
+	de->sampling_period = debugfs_create_u32("sampling_period",
+						 S_IRUSR | S_IWUSR, debugfsdir,
+						 &pinfo->sampling_period);
+	de->coeff_p = debugfs_create_u32("coeff_p", S_IRUSR | S_IWUSR,
+					 debugfsdir, (u32 *)&pinfo->coeff_p);
+	de->coeff_i = debugfs_create_u32("coeff_i", S_IRUSR | S_IWUSR,
+					 debugfsdir, (u32 *)&pinfo->coeff_i);
+	de->coeff_d = debugfs_create_u32("coeff_d", S_IRUSR | S_IWUSR,
+					 debugfsdir, (u32 *)&pinfo->coeff_d);
+	de->smoothing_shift = debugfs_create_u32("smoothing_shift",
+						 S_IRUSR | S_IWUSR, debugfsdir,
+						 &pinfo->smoothing_shift);
+	de->sharpen_factor = debugfs_create_u32("sharpen_factor",
+					       S_IRUSR | S_IWUSR, debugfsdir,
+					       &pinfo->sharpen_factor);
+	de->sharpen_duration = debugfs_create_u32("sharpen_duration",
+						  S_IRUSR | S_IWUSR, debugfsdir,
+						  &pinfo->sharpen_duration);
+	de->norm_offset = debugfs_create_u32("norm_offset",
+					     S_IRUSR | S_IWUSR, debugfsdir,
+					     &pinfo->norm_offset);
+#endif
+
+	return pinfo;
+}
+
+static void rate_control_pid_free(void *priv)
+{
+	struct rc_pid_info *pinfo = priv;
+#ifdef CPTCFG_MAC80211_DEBUGFS
+	struct rc_pid_debugfs_entries *de = &pinfo->dentries;
+
+	debugfs_remove(de->norm_offset);
+	debugfs_remove(de->sharpen_duration);
+	debugfs_remove(de->sharpen_factor);
+	debugfs_remove(de->smoothing_shift);
+	debugfs_remove(de->coeff_d);
+	debugfs_remove(de->coeff_i);
+	debugfs_remove(de->coeff_p);
+	debugfs_remove(de->sampling_period);
+	debugfs_remove(de->target);
+#endif
+
+	kfree(pinfo->rinfo);
+	kfree(pinfo);
+}
+
+static void *rate_control_pid_alloc_sta(void *priv, struct ieee80211_sta *sta,
+					gfp_t gfp)
+{
+	struct rc_pid_sta_info *spinfo;
+
+	spinfo = kzalloc(sizeof(*spinfo), gfp);
+	if (spinfo == NULL)
+		return NULL;
+
+	spinfo->last_sample = jiffies;
+
+#ifdef CPTCFG_MAC80211_DEBUGFS
+	spin_lock_init(&spinfo->events.lock);
+	init_waitqueue_head(&spinfo->events.waitqueue);
+#endif
+
+	return spinfo;
+}
+
+static void rate_control_pid_free_sta(void *priv, struct ieee80211_sta *sta,
+				      void *priv_sta)
+{
+	kfree(priv_sta);
+}
+
+static struct rate_control_ops mac80211_rcpid = {
+	.name = "pid",
+	.tx_status = rate_control_pid_tx_status,
+	.get_rate = rate_control_pid_get_rate,
+	.rate_init = rate_control_pid_rate_init,
+	.alloc = rate_control_pid_alloc,
+	.free = rate_control_pid_free,
+	.alloc_sta = rate_control_pid_alloc_sta,
+	.free_sta = rate_control_pid_free_sta,
+#ifdef CPTCFG_MAC80211_DEBUGFS
+	.add_sta_debugfs = rate_control_pid_add_sta_debugfs,
+	.remove_sta_debugfs = rate_control_pid_remove_sta_debugfs,
+#endif
+};
+
+int __init rc80211_pid_init(void)
+{
+	return ieee80211_rate_control_register(&mac80211_rcpid);
+}
+
+void rc80211_pid_exit(void)
+{
+	ieee80211_rate_control_unregister(&mac80211_rcpid);
+}