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authorroot <root@artemis.panaceas.org>2015-12-25 15:00:15 +0000
committerroot <root@artemis.panaceas.org>2015-12-25 15:00:15 +0000
commitddd86436f4e3643c04b797f858dab95d5f2e4de9 (patch)
treebfe7a780cf9a2f4fc33aec32c82e625e79dece1f /net/mac80211/rc80211_pid_algo.c
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Diffstat (limited to 'net/mac80211/rc80211_pid_algo.c')
-rw-r--r--net/mac80211/rc80211_pid_algo.c477
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);
+}