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-rw-r--r--net/mac80211/rc80211_pid_algo.c549
1 files changed, 549 insertions, 0 deletions
diff --git a/net/mac80211/rc80211_pid_algo.c b/net/mac80211/rc80211_pid_algo.c
new file mode 100644
index 00000000000..554c4baed6f
--- /dev/null
+++ b/net/mac80211/rc80211_pid_algo.c
@@ -0,0 +1,549 @@
+/*
+ * Copyright 2002-2005, Instant802 Networks, Inc.
+ * Copyright 2005, Devicescape Software, Inc.
+ * Copyright 2007, Mattias Nissler <mattias.nissler@gmx.de>
+ * Copyright 2007, 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 <net/mac80211.h>
+#include "ieee80211_rate.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.
+ */
+
+
+/* Shift the adjustment so 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 adjustment is within the ranges. Then,
+ * provide the new rate index. */
+static int rate_control_pid_shift_adjust(struct rc_pid_rateinfo *r,
+ int adj, int cur, int l)
+{
+ int i, j, k, tmp;
+
+ j = r[cur].rev_index;
+ i = j + adj;
+
+ if (i < 0)
+ return r[0].index;
+ if (i >= l - 1)
+ return r[l - 1].index;
+
+ tmp = i;
+
+ if (adj < 0) {
+ for (k = j; k >= i; k--)
+ if (r[k].diff <= r[j].diff)
+ tmp = k;
+ } else {
+ for (k = i + 1; k + i < l; k++)
+ if (r[k].diff <= r[i].diff)
+ tmp = k;
+ }
+
+ return r[tmp].index;
+}
+
+static void rate_control_pid_adjust_rate(struct ieee80211_local *local,
+ struct sta_info *sta, int adj,
+ struct rc_pid_rateinfo *rinfo)
+{
+ struct ieee80211_sub_if_data *sdata;
+ struct ieee80211_hw_mode *mode;
+ int newidx;
+ int maxrate;
+ int back = (adj > 0) ? 1 : -1;
+
+ sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);
+
+ mode = local->oper_hw_mode;
+ maxrate = sdata->bss ? sdata->bss->max_ratectrl_rateidx : -1;
+
+ newidx = rate_control_pid_shift_adjust(rinfo, adj, sta->txrate,
+ mode->num_rates);
+
+ while (newidx != sta->txrate) {
+ if (rate_supported(sta, mode, newidx) &&
+ (maxrate < 0 || newidx <= maxrate)) {
+ sta->txrate = newidx;
+ break;
+ }
+
+ newidx += back;
+ }
+
+#ifdef CONFIG_MAC80211_DEBUGFS
+ rate_control_pid_event_rate_change(
+ &((struct rc_pid_sta_info *)sta->rate_ctrl_priv)->events,
+ newidx, mode->rates[newidx].rate);
+#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_local *local,
+ struct sta_info *sta)
+{
+ struct rc_pid_sta_info *spinfo = sta->rate_ctrl_priv;
+ struct rc_pid_rateinfo *rinfo = pinfo->rinfo;
+ struct ieee80211_hw_mode *mode;
+ u32 pf;
+ s32 err_avg;
+ u32 err_prop;
+ u32 err_int;
+ u32 err_der;
+ int adj, i, j, tmp;
+ unsigned long period;
+
+ mode = local->oper_hw_mode;
+ spinfo = sta->rate_ctrl_priv;
+
+ /* In case nothing happened during the previous control interval, turn
+ * the sharpening factor on. */
+ period = (HZ * pinfo->sampling_period + 500) / 1000;
+ if (!period)
+ period = 1;
+ 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;
+ pf <<= RC_PID_ARITH_SHIFT;
+ }
+
+ spinfo->tx_num_xmit = 0;
+ spinfo->tx_num_failed = 0;
+
+ /* If we just switched rate, update the rate behaviour info. */
+ if (pinfo->oldrate != sta->txrate) {
+
+ i = rinfo[pinfo->oldrate].rev_index;
+ j = rinfo[sta->txrate].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 = sta->txrate;
+ }
+ rate_control_pid_normalize(pinfo, mode->num_rates);
+
+ /* Compute the proportional, integral and derivative errors. */
+ err_prop = (pinfo->target << RC_PID_ARITH_SHIFT) - pf;
+
+ 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 CONFIG_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(local, sta, adj, rinfo);
+}
+
+static void rate_control_pid_tx_status(void *priv, struct net_device *dev,
+ struct sk_buff *skb,
+ struct ieee80211_tx_status *status)
+{
+ struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
+ struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
+ struct ieee80211_sub_if_data *sdata;
+ struct rc_pid_info *pinfo = priv;
+ struct sta_info *sta;
+ struct rc_pid_sta_info *spinfo;
+ unsigned long period;
+
+ sta = sta_info_get(local, hdr->addr1);
+
+ if (!sta)
+ return;
+
+ /* Don't update the state if we're not controlling the rate. */
+ sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);
+ if (sdata->bss && sdata->bss->force_unicast_rateidx > -1) {
+ sta->txrate = sdata->bss->max_ratectrl_rateidx;
+ return;
+ }
+
+ /* Ignore all frames that were sent with a different rate than the rate
+ * we currently advise mac80211 to use. */
+ if (status->control.rate != &local->oper_hw_mode->rates[sta->txrate])
+ goto ignore;
+
+ spinfo = sta->rate_ctrl_priv;
+ spinfo->tx_num_xmit++;
+
+#ifdef CONFIG_MAC80211_DEBUGFS
+ rate_control_pid_event_tx_status(&spinfo->events, status);
+#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 (status->excessive_retries) {
+ spinfo->tx_num_failed += 2;
+ spinfo->tx_num_xmit++;
+ } else if (status->retry_count) {
+ spinfo->tx_num_failed++;
+ spinfo->tx_num_xmit++;
+ }
+
+ if (status->excessive_retries) {
+ sta->tx_retry_failed++;
+ sta->tx_num_consecutive_failures++;
+ sta->tx_num_mpdu_fail++;
+ } else {
+ sta->last_ack_rssi[0] = sta->last_ack_rssi[1];
+ sta->last_ack_rssi[1] = sta->last_ack_rssi[2];
+ sta->last_ack_rssi[2] = status->ack_signal;
+ sta->tx_num_consecutive_failures = 0;
+ sta->tx_num_mpdu_ok++;
+ }
+ sta->tx_retry_count += status->retry_count;
+ sta->tx_num_mpdu_fail += status->retry_count;
+
+ /* Update PID controller state. */
+ period = (HZ * pinfo->sampling_period + 500) / 1000;
+ if (!period)
+ period = 1;
+ if (time_after(jiffies, spinfo->last_sample + period))
+ rate_control_pid_sample(pinfo, local, sta);
+
+ignore:
+ sta_info_put(sta);
+}
+
+static void rate_control_pid_get_rate(void *priv, struct net_device *dev,
+ struct ieee80211_hw_mode *mode,
+ struct sk_buff *skb,
+ struct rate_selection *sel)
+{
+ struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
+ struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
+ struct ieee80211_sub_if_data *sdata;
+ struct sta_info *sta;
+ int rateidx;
+ u16 fc;
+
+ sta = sta_info_get(local, hdr->addr1);
+
+ /* Send management frames and broadcast/multicast data using lowest
+ * rate. */
+ fc = le16_to_cpu(hdr->frame_control);
+ if ((fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA ||
+ is_multicast_ether_addr(hdr->addr1) || !sta) {
+ sel->rate = rate_lowest(local, mode, sta);
+ if (sta)
+ sta_info_put(sta);
+ return;
+ }
+
+ /* If a forced rate is in effect, select it. */
+ sdata = IEEE80211_DEV_TO_SUB_IF(dev);
+ if (sdata->bss && sdata->bss->force_unicast_rateidx > -1)
+ sta->txrate = sdata->bss->force_unicast_rateidx;
+
+ rateidx = sta->txrate;
+
+ if (rateidx >= mode->num_rates)
+ rateidx = mode->num_rates - 1;
+
+ sta->last_txrate = rateidx;
+
+ sta_info_put(sta);
+
+ sel->rate = &mode->rates[rateidx];
+
+#ifdef CONFIG_MAC80211_DEBUGFS
+ rate_control_pid_event_tx_rate(
+ &((struct rc_pid_sta_info *) sta->rate_ctrl_priv)->events,
+ rateidx, mode->rates[rateidx].rate);
+#endif
+}
+
+static void rate_control_pid_rate_init(void *priv, void *priv_sta,
+ struct ieee80211_local *local,
+ struct sta_info *sta)
+{
+ /* 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. */
+ sta->txrate = rate_lowest_index(local, local->oper_hw_mode, sta);
+}
+
+static void *rate_control_pid_alloc(struct ieee80211_local *local)
+{
+ struct rc_pid_info *pinfo;
+ struct rc_pid_rateinfo *rinfo;
+ struct ieee80211_hw_mode *mode;
+ int i, j, tmp;
+ bool s;
+#ifdef CONFIG_MAC80211_DEBUGFS
+ struct rc_pid_debugfs_entries *de;
+#endif
+
+ pinfo = kmalloc(sizeof(*pinfo), GFP_ATOMIC);
+ if (!pinfo)
+ return NULL;
+
+ /* We can safely assume that oper_hw_mode won't change unless we get
+ * reinitialized. */
+ mode = local->oper_hw_mode;
+ rinfo = kmalloc(sizeof(*rinfo) * mode->num_rates, GFP_ATOMIC);
+ if (!rinfo) {
+ kfree(pinfo);
+ return NULL;
+ }
+
+ /* 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 < mode->num_rates; i++) {
+ rinfo[i].index = i;
+ rinfo[i].rev_index = i;
+ if (pinfo->fast_start)
+ rinfo[i].diff = 0;
+ else
+ rinfo[i].diff = i * pinfo->norm_offset;
+ }
+ for (i = 1; i < mode->num_rates; i++) {
+ s = 0;
+ for (j = 0; j < mode->num_rates - i; j++)
+ if (unlikely(mode->rates[rinfo[j].index].rate >
+ mode->rates[rinfo[j + 1].index].rate)) {
+ 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 = 1;
+ }
+ if (!s)
+ break;
+ }
+
+ 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->fast_start = RC_PID_FAST_START;
+ pinfo->rinfo = rinfo;
+ pinfo->oldrate = 0;
+
+#ifdef CONFIG_MAC80211_DEBUGFS
+ de = &pinfo->dentries;
+ de->dir = debugfs_create_dir("rc80211_pid",
+ local->hw.wiphy->debugfsdir);
+ de->target = debugfs_create_u32("target_pf", S_IRUSR | S_IWUSR,
+ de->dir, &pinfo->target);
+ de->sampling_period = debugfs_create_u32("sampling_period",
+ S_IRUSR | S_IWUSR, de->dir,
+ &pinfo->sampling_period);
+ de->coeff_p = debugfs_create_u32("coeff_p", S_IRUSR | S_IWUSR,
+ de->dir, &pinfo->coeff_p);
+ de->coeff_i = debugfs_create_u32("coeff_i", S_IRUSR | S_IWUSR,
+ de->dir, &pinfo->coeff_i);
+ de->coeff_d = debugfs_create_u32("coeff_d", S_IRUSR | S_IWUSR,
+ de->dir, &pinfo->coeff_d);
+ de->smoothing_shift = debugfs_create_u32("smoothing_shift",
+ S_IRUSR | S_IWUSR, de->dir,
+ &pinfo->smoothing_shift);
+ de->sharpen_factor = debugfs_create_u32("sharpen_factor",
+ S_IRUSR | S_IWUSR, de->dir,
+ &pinfo->sharpen_factor);
+ de->sharpen_duration = debugfs_create_u32("sharpen_duration",
+ S_IRUSR | S_IWUSR, de->dir,
+ &pinfo->sharpen_duration);
+ de->norm_offset = debugfs_create_u32("norm_offset",
+ S_IRUSR | S_IWUSR, de->dir,
+ &pinfo->norm_offset);
+ de->fast_start = debugfs_create_bool("fast_start",
+ S_IRUSR | S_IWUSR, de->dir,
+ &pinfo->fast_start);
+#endif
+
+ return pinfo;
+}
+
+static void rate_control_pid_free(void *priv)
+{
+ struct rc_pid_info *pinfo = priv;
+#ifdef CONFIG_MAC80211_DEBUGFS
+ struct rc_pid_debugfs_entries *de = &pinfo->dentries;
+
+ debugfs_remove(de->fast_start);
+ 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);
+ debugfs_remove(de->dir);
+#endif
+
+ kfree(pinfo->rinfo);
+ kfree(pinfo);
+}
+
+static void rate_control_pid_clear(void *priv)
+{
+}
+
+static void *rate_control_pid_alloc_sta(void *priv, gfp_t gfp)
+{
+ struct rc_pid_sta_info *spinfo;
+
+ spinfo = kzalloc(sizeof(*spinfo), gfp);
+ if (spinfo == NULL)
+ return NULL;
+
+ spinfo->last_sample = jiffies;
+
+#ifdef CONFIG_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, void *priv_sta)
+{
+ struct rc_pid_sta_info *spinfo = priv_sta;
+ kfree(spinfo);
+}
+
+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,
+ .clear = rate_control_pid_clear,
+ .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 CONFIG_MAC80211_DEBUGFS
+ .add_sta_debugfs = rate_control_pid_add_sta_debugfs,
+ .remove_sta_debugfs = rate_control_pid_remove_sta_debugfs,
+#endif
+};
+
+MODULE_DESCRIPTION("PID controller based rate control algorithm");
+MODULE_AUTHOR("Stefano Brivio");
+MODULE_AUTHOR("Mattias Nissler");
+MODULE_LICENSE("GPL");
+
+int __init rc80211_pid_init(void)
+{
+ return ieee80211_rate_control_register(&mac80211_rcpid);
+}
+
+void __exit rc80211_pid_exit(void)
+{
+ ieee80211_rate_control_unregister(&mac80211_rcpid);
+}
+
+#ifdef CONFIG_MAC80211_RC_PID_MODULE
+module_init(rc80211_pid_init);
+module_exit(rc80211_pid_exit);
+#endif