--- /dev/null
+/*
+ * 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 */
projects / openwrt.git / blobdiff