2.6.25-rc7

 net

 mac80211

diff --git a/net/mac80211/rc80211_pid_algo.c b/net/mac80211/rc80211_pid_algo.c
new file mode 100644
index 0000000..3b77410
--- /dev/null
+++ b/net/mac80211/rc80211_pid_algo.c
@@ -0,0 +1,543 @@
+/*
+ * 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 <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.
+ */
+
+/* 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_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 cur_sorted, new_sorted, probe, tmp, n_bitrates;
+   int cur = sta->txrate;
+
+   sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);
+
+   mode = local->oper_hw_mode;
+   n_bitrates = mode->num_rates;
+
+   /* 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, mode, 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, mode, rinfo[probe].index))
+            tmp = probe;
+   }
+
+   /* Fit the rate found to the nearest supported rate. */
+   do {
+      if (rate_supported(sta, mode, rinfo[tmp].index)) {
+         sta->txrate = rinfo[tmp].index;
+         break;
+      }
+      if (adj < 0)
+         tmp--;
+      else
+         tmp++;
+   } while (tmp < n_bitrates && tmp >= 0);
+
+#ifdef CONFIG_MAC80211_DEBUGFS
+   rate_control_pid_event_rate_change(
+      &((struct rc_pid_sta_info *)sta->rate_ctrl_priv)->events,
+      cur, mode->rates[cur].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 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