282 lines
7.8 KiB
C
282 lines
7.8 KiB
C
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/*
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* Copyright 2007, Mattias Nissler <mattias.nissler@gmx.de>
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* Copyright 2007, Stefano Brivio <stefano.brivio@polimi.it>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#ifndef RC80211_PID_H
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#define RC80211_PID_H
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/* Sampling period for measuring percentage of failed frames in ms. */
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#define RC_PID_INTERVAL 125
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/* Exponential averaging smoothness (used for I part of PID controller) */
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#define RC_PID_SMOOTHING_SHIFT 3
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#define RC_PID_SMOOTHING (1 << RC_PID_SMOOTHING_SHIFT)
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/* Sharpening factor (used for D part of PID controller) */
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#define RC_PID_SHARPENING_FACTOR 0
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#define RC_PID_SHARPENING_DURATION 0
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/* Fixed point arithmetic shifting amount. */
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#define RC_PID_ARITH_SHIFT 8
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/* Fixed point arithmetic factor. */
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#define RC_PID_ARITH_FACTOR (1 << RC_PID_ARITH_SHIFT)
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/* Proportional PID component coefficient. */
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#define RC_PID_COEFF_P 15
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/* Integral PID component coefficient. */
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#define RC_PID_COEFF_I 9
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/* Derivative PID component coefficient. */
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#define RC_PID_COEFF_D 15
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/* Target failed frames rate for the PID controller. NB: This effectively gives
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* maximum failed frames percentage we're willing to accept. If the wireless
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* link quality is good, the controller will fail to adjust failed frames
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* percentage to the target. This is intentional.
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*/
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#define RC_PID_TARGET_PF 14
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/* Rate behaviour normalization quantity over time. */
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#define RC_PID_NORM_OFFSET 3
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/* Push high rates right after loading. */
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#define RC_PID_FAST_START 0
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/* Arithmetic right shift for positive and negative values for ISO C. */
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#define RC_PID_DO_ARITH_RIGHT_SHIFT(x, y) \
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((x) < 0 ? -((-(x)) >> (y)) : (x) >> (y))
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enum rc_pid_event_type {
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RC_PID_EVENT_TYPE_TX_STATUS,
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RC_PID_EVENT_TYPE_RATE_CHANGE,
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RC_PID_EVENT_TYPE_TX_RATE,
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RC_PID_EVENT_TYPE_PF_SAMPLE,
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};
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union rc_pid_event_data {
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/* RC_PID_EVENT_TX_STATUS */
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struct {
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u32 flags;
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struct ieee80211_tx_info tx_status;
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};
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/* RC_PID_EVENT_TYPE_RATE_CHANGE */
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/* RC_PID_EVENT_TYPE_TX_RATE */
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struct {
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int index;
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int rate;
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};
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/* RC_PID_EVENT_TYPE_PF_SAMPLE */
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struct {
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s32 pf_sample;
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s32 prop_err;
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s32 int_err;
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s32 der_err;
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};
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};
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struct rc_pid_event {
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/* The time when the event occured */
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unsigned long timestamp;
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/* Event ID number */
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unsigned int id;
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/* Type of event */
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enum rc_pid_event_type type;
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/* type specific data */
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union rc_pid_event_data data;
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};
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/* Size of the event ring buffer. */
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#define RC_PID_EVENT_RING_SIZE 32
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struct rc_pid_event_buffer {
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/* Counter that generates event IDs */
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unsigned int ev_count;
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/* Ring buffer of events */
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struct rc_pid_event ring[RC_PID_EVENT_RING_SIZE];
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/* Index to the entry in events_buf to be reused */
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unsigned int next_entry;
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/* Lock that guards against concurrent access to this buffer struct */
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spinlock_t lock;
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/* Wait queue for poll/select and blocking I/O */
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wait_queue_head_t waitqueue;
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};
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struct rc_pid_events_file_info {
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/* The event buffer we read */
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struct rc_pid_event_buffer *events;
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/* The entry we have should read next */
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unsigned int next_entry;
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};
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/**
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* struct rc_pid_debugfs_entries - tunable parameters
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*
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* Algorithm parameters, tunable via debugfs.
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* @target: target percentage for failed frames
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* @sampling_period: error sampling interval in milliseconds
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* @coeff_p: absolute value of the proportional coefficient
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* @coeff_i: absolute value of the integral coefficient
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* @coeff_d: absolute value of the derivative coefficient
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* @smoothing_shift: absolute value of the integral smoothing factor (i.e.
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* amount of smoothing introduced by the exponential moving average)
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* @sharpen_factor: absolute value of the derivative sharpening factor (i.e.
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* amount of emphasis given to the derivative term after low activity
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* events)
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* @sharpen_duration: duration of the sharpening effect after the detected low
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* activity event, relative to sampling_period
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* @norm_offset: amount of normalization periodically performed on the learnt
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* rate behaviour values (lower means we should trust more what we learnt
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* about behaviour of rates, higher means we should trust more the natural
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* ordering of rates)
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*/
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struct rc_pid_debugfs_entries {
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struct dentry *target;
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struct dentry *sampling_period;
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struct dentry *coeff_p;
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struct dentry *coeff_i;
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struct dentry *coeff_d;
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struct dentry *smoothing_shift;
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struct dentry *sharpen_factor;
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struct dentry *sharpen_duration;
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struct dentry *norm_offset;
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};
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void rate_control_pid_event_tx_status(struct rc_pid_event_buffer *buf,
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struct ieee80211_tx_info *stat);
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void rate_control_pid_event_rate_change(struct rc_pid_event_buffer *buf,
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int index, int rate);
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void rate_control_pid_event_tx_rate(struct rc_pid_event_buffer *buf,
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int index, int rate);
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void rate_control_pid_event_pf_sample(struct rc_pid_event_buffer *buf,
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s32 pf_sample, s32 prop_err,
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s32 int_err, s32 der_err);
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void rate_control_pid_add_sta_debugfs(void *priv, void *priv_sta,
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struct dentry *dir);
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void rate_control_pid_remove_sta_debugfs(void *priv, void *priv_sta);
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struct rc_pid_sta_info {
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unsigned long last_change;
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unsigned long last_sample;
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u32 tx_num_failed;
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u32 tx_num_xmit;
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int txrate_idx;
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/* Average failed frames percentage error (i.e. actual vs. target
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* percentage), scaled by RC_PID_SMOOTHING. This value is computed
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* using using an exponential weighted average technique:
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*
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* (RC_PID_SMOOTHING - 1) * err_avg_old + err
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* err_avg = ------------------------------------------
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* RC_PID_SMOOTHING
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*
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* where err_avg is the new approximation, err_avg_old the previous one
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* and err is the error w.r.t. to the current failed frames percentage
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* sample. Note that the bigger RC_PID_SMOOTHING the more weight is
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* given to the previous estimate, resulting in smoother behavior (i.e.
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* corresponding to a longer integration window).
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*
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* For computation, we actually don't use the above formula, but this
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* one:
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*
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* err_avg_scaled = err_avg_old_scaled - err_avg_old + err
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*
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* where:
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* err_avg_scaled = err * RC_PID_SMOOTHING
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* err_avg_old_scaled = err_avg_old * RC_PID_SMOOTHING
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*
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* This avoids floating point numbers and the per_failed_old value can
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* easily be obtained by shifting per_failed_old_scaled right by
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* RC_PID_SMOOTHING_SHIFT.
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*/
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s32 err_avg_sc;
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/* Last framed failes percentage sample. */
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u32 last_pf;
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/* Sharpening needed. */
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u8 sharp_cnt;
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#ifdef CONFIG_MAC80211_DEBUGFS
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/* Event buffer */
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struct rc_pid_event_buffer events;
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/* Events debugfs file entry */
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struct dentry *events_entry;
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#endif
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};
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/* Algorithm parameters. We keep them on a per-algorithm approach, so they can
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* be tuned individually for each interface.
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*/
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struct rc_pid_rateinfo {
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/* Map sorted rates to rates in ieee80211_hw_mode. */
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int index;
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/* Map rates in ieee80211_hw_mode to sorted rates. */
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int rev_index;
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/* Did we do any measurement on this rate? */
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bool valid;
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/* Comparison with the lowest rate. */
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int diff;
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};
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struct rc_pid_info {
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/* The failed frames percentage target. */
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unsigned int target;
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/* Rate at which failed frames percentage is sampled in 0.001s. */
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unsigned int sampling_period;
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/* P, I and D coefficients. */
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int coeff_p;
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int coeff_i;
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int coeff_d;
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/* Exponential averaging shift. */
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unsigned int smoothing_shift;
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/* Sharpening factor and duration. */
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unsigned int sharpen_factor;
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unsigned int sharpen_duration;
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/* Normalization offset. */
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unsigned int norm_offset;
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/* Rates information. */
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struct rc_pid_rateinfo *rinfo;
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/* Index of the last used rate. */
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int oldrate;
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#ifdef CONFIG_MAC80211_DEBUGFS
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/* Debugfs entries created for the parameters above. */
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struct rc_pid_debugfs_entries dentries;
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#endif
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};
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#endif /* RC80211_PID_H */
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