diff options
Diffstat (limited to 'net/mac80211/rc80211_pid.h')
| -rw-r--r-- | net/mac80211/rc80211_pid.h | 285 |
1 files changed, 285 insertions, 0 deletions
diff --git a/net/mac80211/rc80211_pid.h b/net/mac80211/rc80211_pid.h new file mode 100644 index 00000000000..04afc13ed82 --- /dev/null +++ b/net/mac80211/rc80211_pid.h @@ -0,0 +1,285 @@ +/* + * 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. + */ + +#ifndef RC80211_PID_H +#define RC80211_PID_H + +/* Sampling period for measuring percentage of failed frames in ms. */ +#define RC_PID_INTERVAL 125 + +/* 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) + +/* Sharpening factor (used for D part of PID controller) */ +#define RC_PID_SHARPENING_FACTOR 0 +#define RC_PID_SHARPENING_DURATION 0 + +/* 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 14 + +/* Rate behaviour normalization quantity over time. */ +#define RC_PID_NORM_OFFSET 3 + +/* Push high rates right after loading. */ +#define RC_PID_FAST_START 0 + +/* Arithmetic right shift for positive and negative values for ISO C. */ +#define RC_PID_DO_ARITH_RIGHT_SHIFT(x, y) \ + (x) < 0 ? -((-(x)) >> (y)) : (x) >> (y) + +enum rc_pid_event_type { + RC_PID_EVENT_TYPE_TX_STATUS, + RC_PID_EVENT_TYPE_RATE_CHANGE, + RC_PID_EVENT_TYPE_TX_RATE, + RC_PID_EVENT_TYPE_PF_SAMPLE, +}; + +union rc_pid_event_data { + /* RC_PID_EVENT_TX_STATUS */ + struct { + struct ieee80211_tx_status tx_status; + }; + /* RC_PID_EVENT_TYPE_RATE_CHANGE */ + /* RC_PID_EVENT_TYPE_TX_RATE */ + struct { + int index; + int rate; + }; + /* RC_PID_EVENT_TYPE_PF_SAMPLE */ + struct { + s32 pf_sample; + s32 prop_err; + s32 int_err; + s32 der_err; + }; +}; + +struct rc_pid_event { + /* The time when the event occured */ + unsigned long timestamp; + + /* Event ID number */ + unsigned int id; + + /* Type of event */ + enum rc_pid_event_type type; + + /* type specific data */ + union rc_pid_event_data data; +}; + +/* Size of the event ring buffer. */ +#define RC_PID_EVENT_RING_SIZE 32 + +struct rc_pid_event_buffer { + /* Counter that generates event IDs */ + unsigned int ev_count; + + /* Ring buffer of events */ + struct rc_pid_event ring[RC_PID_EVENT_RING_SIZE]; + + /* Index to the entry in events_buf to be reused */ + unsigned int next_entry; + + /* Lock that guards against concurrent access to this buffer struct */ + spinlock_t lock; + + /* Wait queue for poll/select and blocking I/O */ + wait_queue_head_t waitqueue; +}; + +struct rc_pid_events_file_info { + /* The event buffer we read */ + struct rc_pid_event_buffer *events; + + /* The entry we have should read next */ + unsigned int next_entry; +}; + +/** + * struct rc_pid_debugfs_entries - tunable parameters + * + * Algorithm parameters, tunable via debugfs. + * @dir: the debugfs directory for a specific phy + * @target: target percentage for failed frames + * @sampling_period: error sampling interval in milliseconds + * @coeff_p: absolute value of the proportional coefficient + * @coeff_i: absolute value of the integral coefficient + * @coeff_d: absolute value of the derivative coefficient + * @smoothing_shift: absolute value of the integral smoothing factor (i.e. + * amount of smoothing introduced by the exponential moving average) + * @sharpen_factor: absolute value of the derivative sharpening factor (i.e. + * amount of emphasis given to the derivative term after low activity + * events) + * @sharpen_duration: duration of the sharpening effect after the detected low + * activity event, relative to sampling_period + * @norm_offset: amount of normalization periodically performed on the learnt + * rate behaviour values (lower means we should trust more what we learnt + * about behaviour of rates, higher means we should trust more the natural + * ordering of rates) + * @fast_start: if Y, push high rates right after initialization + */ +struct rc_pid_debugfs_entries { + struct dentry *dir; + struct dentry *target; + struct dentry *sampling_period; + struct dentry *coeff_p; + struct dentry *coeff_i; + struct dentry *coeff_d; + struct dentry *smoothing_shift; + struct dentry *sharpen_factor; + struct dentry *sharpen_duration; + struct dentry *norm_offset; + struct dentry *fast_start; +}; + +void rate_control_pid_event_tx_status(struct rc_pid_event_buffer *buf, + struct ieee80211_tx_status *stat); + +void rate_control_pid_event_rate_change(struct rc_pid_event_buffer *buf, + int index, int rate); + +void rate_control_pid_event_tx_rate(struct rc_pid_event_buffer *buf, + int index, int rate); + +void rate_control_pid_event_pf_sample(struct rc_pid_event_buffer *buf, + s32 pf_sample, s32 prop_err, + s32 int_err, s32 der_err); + +void rate_control_pid_add_sta_debugfs(void *priv, void *priv_sta, + struct dentry *dir); + +void rate_control_pid_remove_sta_debugfs(void *priv, void *priv_sta); + +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; + + /* Sharpening needed. */ + u8 sharp_cnt; + +#ifdef CONFIG_MAC80211_DEBUGFS + /* Event buffer */ + struct rc_pid_event_buffer events; + + /* Events debugfs file entry */ + struct dentry *events_entry; +#endif +}; + +/* Algorithm parameters. We keep them on a per-algorithm approach, so they can + * be tuned individually for each interface. + */ +struct rc_pid_rateinfo { + + /* Map sorted rates to rates in ieee80211_hw_mode. */ + int index; + + /* Map rates in ieee80211_hw_mode to sorted rates. */ + int rev_index; + + /* Did we do any measurement on this rate? */ + bool valid; + + /* Comparison with the lowest rate. */ + int diff; +}; + +struct rc_pid_info { + + /* The failed frames percentage target. */ + unsigned int target; + + /* Rate at which failed frames percentage is sampled in 0.001s. */ + unsigned int sampling_period; + + /* P, I and D coefficients. */ + int coeff_p; + int coeff_i; + int coeff_d; + + /* Exponential averaging shift. */ + unsigned int smoothing_shift; + + /* Sharpening factor and duration. */ + unsigned int sharpen_factor; + unsigned int sharpen_duration; + + /* Normalization offset. */ + unsigned int norm_offset; + + /* Fast starst parameter. */ + unsigned int fast_start; + + /* Rates information. */ + struct rc_pid_rateinfo *rinfo; + + /* Index of the last used rate. */ + int oldrate; + +#ifdef CONFIG_MAC80211_DEBUGFS + /* Debugfs entries created for the parameters above. */ + struct rc_pid_debugfs_entries dentries; +#endif +}; + +#endif /* RC80211_PID_H */ |