diff options
Diffstat (limited to 'net/mac80211/rc80211_pid_algo.c')
| -rw-r--r-- | net/mac80211/rc80211_pid_algo.c | 549 |
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 000000000000..554c4baed6fb --- /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 |