diff options
Diffstat (limited to 'net/mac80211')
| -rw-r--r-- | net/mac80211/Kconfig | 12 | ||||
| -rw-r--r-- | net/mac80211/Makefile | 1 | ||||
| -rw-r--r-- | net/mac80211/ieee80211.c | 27 | ||||
| -rw-r--r-- | net/mac80211/ieee80211_rate.h | 3 | ||||
| -rw-r--r-- | net/mac80211/rc80211_pid.c | 365 |
5 files changed, 403 insertions, 5 deletions
diff --git a/net/mac80211/Kconfig b/net/mac80211/Kconfig index 09711b06280..9f8663b412d 100644 --- a/net/mac80211/Kconfig +++ b/net/mac80211/Kconfig @@ -25,6 +25,18 @@ config MAC80211_RCSIMPLE Say Y unless you know you will have another algorithm available. +config MAC80211_RCPID + bool "'PID' rate control algorithm" if EMBEDDED + default y + depends on MAC80211 + help + This option enables a TX rate control algorithm for + mac80211 that uses a PID controller to select the TX + rate. + + Say Y unless you're sure you want to use a different + rate control algorithm. + config MAC80211_LEDS bool "Enable LED triggers" depends on MAC80211 && LEDS_TRIGGERS diff --git a/net/mac80211/Makefile b/net/mac80211/Makefile index 1e6237b3484..62c01ca099e 100644 --- a/net/mac80211/Makefile +++ b/net/mac80211/Makefile @@ -4,6 +4,7 @@ mac80211-objs-$(CONFIG_MAC80211_LEDS) += ieee80211_led.o mac80211-objs-$(CONFIG_MAC80211_DEBUGFS) += debugfs.o debugfs_sta.o debugfs_netdev.o debugfs_key.o mac80211-objs-$(CONFIG_NET_SCHED) += wme.o mac80211-objs-$(CONFIG_MAC80211_RCSIMPLE) += rc80211_simple.o +mac80211-objs-$(CONFIG_MAC80211_RCPID) += rc80211_pid.o mac80211-objs := \ ieee80211.o \ diff --git a/net/mac80211/ieee80211.c b/net/mac80211/ieee80211.c index 5bf7a5bebfc..3d7b4341914 100644 --- a/net/mac80211/ieee80211.c +++ b/net/mac80211/ieee80211.c @@ -1315,23 +1315,37 @@ static int __init ieee80211_init(void) #ifdef CONFIG_MAC80211_RCSIMPLE ret = ieee80211_rate_control_register(&mac80211_rcsimple); if (ret) - return ret; + goto fail; +#endif + +#ifdef CONFIG_MAC80211_RCPID + ret = ieee80211_rate_control_register(&mac80211_rcpid); + if (ret) + goto fail; #endif ret = ieee80211_wme_register(); if (ret) { -#ifdef CONFIG_MAC80211_RCSIMPLE - ieee80211_rate_control_unregister(&mac80211_rcsimple); -#endif printk(KERN_DEBUG "ieee80211_init: failed to " "initialize WME (err=%d)\n", ret); - return ret; + goto fail; } ieee80211_debugfs_netdev_init(); ieee80211_regdomain_init(); return 0; + +fail: + +#ifdef CONFIG_MAC80211_RCSIMPLE + ieee80211_rate_control_unregister(&mac80211_rcsimple); +#endif +#ifdef CONFIG_MAC80211_RCPID + ieee80211_rate_control_unregister(&mac80211_rcpid); +#endif + + return ret; } static void __exit ieee80211_exit(void) @@ -1339,6 +1353,9 @@ static void __exit ieee80211_exit(void) #ifdef CONFIG_MAC80211_RCSIMPLE ieee80211_rate_control_unregister(&mac80211_rcsimple); #endif +#ifdef CONFIG_MAC80211_RCPID + ieee80211_rate_control_unregister(&mac80211_rcpid); +#endif ieee80211_wme_unregister(); ieee80211_debugfs_netdev_exit(); diff --git a/net/mac80211/ieee80211_rate.h b/net/mac80211/ieee80211_rate.h index 787134bd6ab..3eb0696f375 100644 --- a/net/mac80211/ieee80211_rate.h +++ b/net/mac80211/ieee80211_rate.h @@ -61,6 +61,9 @@ struct rate_control_ref { /* default 'simple' algorithm */ extern struct rate_control_ops mac80211_rcsimple; +/* 'PID' algorithm */ +extern struct rate_control_ops mac80211_rcpid; + int ieee80211_rate_control_register(struct rate_control_ops *ops); void ieee80211_rate_control_unregister(struct rate_control_ops *ops); diff --git a/net/mac80211/rc80211_pid.c b/net/mac80211/rc80211_pid.c new file mode 100644 index 00000000000..b358824b5ac --- /dev/null +++ b/net/mac80211/rc80211_pid.c @@ -0,0 +1,365 @@ +/* + * Copyright 2002-2005, Instant802 Networks, Inc. + * Copyright 2005, Devicescape Software, Inc. + * Copyright 2007, Mattias Nissler <mattias.nissler@gmx.de> + * + * 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 <net/mac80211.h> +#include "ieee80211_rate.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) + * + * 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 + * 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 need to map it to a TX rate to be selected. + * For now, we depend on the rates to be ordered in a way such that more robust + * rates (i.e. such that exhibit a lower framed failed percentage) come first. + * E.g. for the 802.11b/g case, we first have the b rates in ascending order, + * then the g rates. The adj simply decides the index of the TX rate in the list + * to switch to (relative to the current TX rate entry). + * + * 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. + */ + +/* Sampling period for measuring percentage of failed frames. */ +#define RC_PID_INTERVAL (HZ / 8) + +/* Exponential averaging smoothness (used for I part of PID controller) */ +#define RC_PID_SMOOTHING_SHIFT 3 +#define RC_PID_SMOOTHING (1 << RC_PID_SMOOTHING_SHIFT) + +/* Fixed point arithmetic shifting amount. */ +#define RC_PID_ARITH_SHIFT 8 + +/* Fixed point arithmetic factor. */ +#define RC_PID_ARITH_FACTOR (1 << RC_PID_ARITH_SHIFT) + +/* Proportional PID component coefficient. */ +#define RC_PID_COEFF_P 15 +/* Integral PID component coefficient. */ +#define RC_PID_COEFF_I 9 +/* Derivative PID component coefficient. */ +#define RC_PID_COEFF_D 15 + +/* Target failed frames rate for the PID controller. NB: This effectively gives + * maximum failed frames percentage we're willing to accept. If the wireless + * link quality is good, the controller will fail to adjust failed frames + * percentage to the target. This is intentional. + */ +#define RC_PID_TARGET_PF (11 << RC_PID_ARITH_SHIFT) + +struct rc_pid_sta_info { + unsigned long last_change; + unsigned long last_sample; + + u32 tx_num_failed; + u32 tx_num_xmit; + + /* Average failed frames percentage error (i.e. actual vs. target + * percentage), scaled by RC_PID_SMOOTHING. This value is computed + * using using an exponential weighted average technique: + * + * (RC_PID_SMOOTHING - 1) * err_avg_old + err + * err_avg = ------------------------------------------ + * RC_PID_SMOOTHING + * + * where err_avg is the new approximation, err_avg_old the previous one + * and err is the error w.r.t. to the current failed frames percentage + * sample. Note that the bigger RC_PID_SMOOTHING the more weight is + * given to the previous estimate, resulting in smoother behavior (i.e. + * corresponding to a longer integration window). + * + * For computation, we actually don't use the above formula, but this + * one: + * + * err_avg_scaled = err_avg_old_scaled - err_avg_old + err + * + * where: + * err_avg_scaled = err * RC_PID_SMOOTHING + * err_avg_old_scaled = err_avg_old * RC_PID_SMOOTHING + * + * This avoids floating point numbers and the per_failed_old value can + * easily be obtained by shifting per_failed_old_scaled right by + * RC_PID_SMOOTHING_SHIFT. + */ + s32 err_avg_sc; + + /* Last framed failes percentage sample */ + u32 last_pf; +}; + +/* Algorithm parameters. We keep them on a per-algorithm approach, so they can + * be tuned individually for each interface. + */ +struct rc_pid_info { + + /* The failed frames percentage target. */ + u32 target; + + /* P, I and D coefficients. */ + s32 coeff_p; + s32 coeff_i; + s32 coeff_d; +}; + + +static void rate_control_pid_adjust_rate(struct ieee80211_local *local, + struct sta_info *sta, int adj) +{ + struct ieee80211_sub_if_data *sdata; + struct ieee80211_hw_mode *mode; + int newidx = sta->txrate + adj; + int maxrate; + int back = (adj > 0) ? 1 : -1; + + sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev); + if (sdata->bss && sdata->bss->force_unicast_rateidx > -1) { + /* forced unicast rate - do not change STA rate */ + return; + } + + mode = local->oper_hw_mode; + maxrate = sdata->bss ? sdata->bss->max_ratectrl_rateidx : -1; + + if (newidx < 0) + newidx = 0; + else if (newidx >= mode->num_rates) + newidx = mode->num_rates - 1; + + while (newidx != sta->txrate) { + if (rate_supported(sta, mode, newidx) && + (maxrate < 0 || newidx <= maxrate)) { + sta->txrate = newidx; + break; + } + + newidx += back; + } +} + +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; + u32 pf; + s32 err_avg; + s32 err_prop; + s32 err_int; + s32 err_der; + int adj; + + spinfo = sta->rate_ctrl_priv; + spinfo->last_sample = jiffies; + + /* If no frames were transmitted, we assume the old sample is + * still a good measurement and copy it. */ + if (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; + } + + /* Compute the proportional, integral and derivative errors. */ + err_prop = RC_PID_TARGET_PF - pf; + + err_avg = spinfo->err_avg_sc >> RC_PID_SMOOTHING_SHIFT; + spinfo->err_avg_sc = spinfo->err_avg_sc - err_avg + err_prop; + err_int = spinfo->err_avg_sc >> RC_PID_SMOOTHING_SHIFT; + + err_der = pf - spinfo->last_pf; + spinfo->last_pf = pf; + + /* Compute the controller output. */ + adj = (err_prop * pinfo->coeff_p + err_int * pinfo->coeff_i + + err_der * pinfo->coeff_d); + + /* We need to do an arithmetic right shift. ISO C says this is + * implementation defined for negative left operands. Hence, be + * careful to get it right, also for negative values. */ + adj = (adj < 0) ? -((-adj) >> (2 * RC_PID_ARITH_SHIFT)) : + adj >> (2 * RC_PID_ARITH_SHIFT); + + /* Change rate. */ + if (adj) + rate_control_pid_adjust_rate(local, sta, adj); +} + +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 rc_pid_info *pinfo = priv; + struct sta_info *sta; + struct rc_pid_sta_info *spinfo; + + sta = sta_info_get(local, hdr->addr1); + + if (!sta) + 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]) + return; + + spinfo = sta->rate_ctrl_priv; + spinfo->tx_num_xmit++; + + /* 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. */ + if (time_after(jiffies, spinfo->last_sample + RC_PID_INTERVAL)) + rate_control_pid_sample(pinfo, local, sta); + + 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 sta_info *sta; + int rateidx; + + sta = sta_info_get(local, hdr->addr1); + + if (!sta) { + sel->rate = rate_lowest(local, mode, NULL); + sta_info_put(sta); + return; + } + + rateidx = sta->txrate; + + if (rateidx >= mode->num_rates) + rateidx = mode->num_rates - 1; + + sta_info_put(sta); + + sel->rate = &mode->rates[rateidx]; +} + +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; + + pinfo = kmalloc(sizeof(*pinfo), GFP_ATOMIC); + + pinfo->target = RC_PID_TARGET_PF; + pinfo->coeff_p = RC_PID_COEFF_P; + pinfo->coeff_i = RC_PID_COEFF_I; + pinfo->coeff_d = RC_PID_COEFF_D; + + return pinfo; +} + +static void rate_control_pid_free(void *priv) +{ + struct rc_pid_info *pinfo = priv; + 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); + + return spinfo; +} + +static void rate_control_pid_free_sta(void *priv, void *priv_sta) +{ + struct rc_pid_sta_info *spinfo = priv_sta; + kfree(spinfo); +} + +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, +}; |