forked from Minki/linux
4c6d4f5c33
All current rate control algorithms agree to send management and no-ack frames at the lowest rate. They also agree to do this when sta and the private rate control data is NULL. We add a hlper to mac80211 for this and simplify the rate control algorithm code. Developers wishing to make enhancements to rate control algorithms are for broadcast/multicast can opt to not use this in their gate_rate() mac80211 callback. Cc: Zhu Yi <yi.zhu@intel.com> Acked-by: Reinette Chatre <reinette.chatre@intel.com> Cc: ipw3945-devel@lists.sourceforge.net Cc: Gabor Juhos <juhosg@openwrt.org> Acked-by: Felix Fietkau <nbd@openwrt.org> Cc: Derek Smithies <derek@indranet.co.nz> Cc: Chittajit Mitra <Chittajit.Mitra@Atheros.com> Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>
495 lines
15 KiB
C
495 lines
15 KiB
C
/*
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* Copyright 2002-2005, Instant802 Networks, Inc.
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* Copyright 2005, Devicescape Software, Inc.
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* Copyright 2007, Mattias Nissler <mattias.nissler@gmx.de>
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* Copyright 2007-2008, 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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#include <linux/netdevice.h>
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#include <linux/types.h>
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#include <linux/skbuff.h>
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#include <linux/debugfs.h>
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#include <net/mac80211.h>
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#include "rate.h"
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#include "mesh.h"
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#include "rc80211_pid.h"
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/* This is an implementation of a TX rate control algorithm that uses a PID
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* controller. Given a target failed frames rate, the controller decides about
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* TX rate changes to meet the target failed frames rate.
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*
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* The controller basically computes the following:
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*
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* adj = CP * err + CI * err_avg + CD * (err - last_err) * (1 + sharpening)
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*
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* where
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* adj adjustment value that is used to switch TX rate (see below)
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* err current error: target vs. current failed frames percentage
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* last_err last error
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* err_avg average (i.e. poor man's integral) of recent errors
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* sharpening non-zero when fast response is needed (i.e. right after
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* association or no frames sent for a long time), heading
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* to zero over time
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* CP Proportional coefficient
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* CI Integral coefficient
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* CD Derivative coefficient
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*
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* CP, CI, CD are subject to careful tuning.
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*
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* The integral component uses a exponential moving average approach instead of
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* an actual sliding window. The advantage is that we don't need to keep an
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* array of the last N error values and computation is easier.
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*
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* Once we have the adj value, we map it to a rate by means of a learning
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* algorithm. This algorithm keeps the state of the percentual failed frames
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* difference between rates. The behaviour of the lowest available rate is kept
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* as a reference value, and every time we switch between two rates, we compute
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* the difference between the failed frames each rate exhibited. By doing so,
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* we compare behaviours which different rates exhibited in adjacent timeslices,
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* thus the comparison is minimally affected by external conditions. This
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* difference gets propagated to the whole set of measurements, so that the
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* reference is always the same. Periodically, we normalize this set so that
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* recent events weigh the most. By comparing the adj value with this set, we
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* avoid pejorative switches to lower rates and allow for switches to higher
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* rates if they behaved well.
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*
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* Note that for the computations we use a fixed-point representation to avoid
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* floating point arithmetic. Hence, all values are shifted left by
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* RC_PID_ARITH_SHIFT.
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*/
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/* Adjust the rate while ensuring that we won't switch to a lower rate if it
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* exhibited a worse failed frames behaviour and we'll choose the highest rate
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* whose failed frames behaviour is not worse than the one of the original rate
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* target. While at it, check that the new rate is valid. */
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static void rate_control_pid_adjust_rate(struct ieee80211_supported_band *sband,
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struct ieee80211_sta *sta,
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struct rc_pid_sta_info *spinfo, int adj,
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struct rc_pid_rateinfo *rinfo)
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{
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int cur_sorted, new_sorted, probe, tmp, n_bitrates, band;
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int cur = spinfo->txrate_idx;
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band = sband->band;
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n_bitrates = sband->n_bitrates;
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/* Map passed arguments to sorted values. */
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cur_sorted = rinfo[cur].rev_index;
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new_sorted = cur_sorted + adj;
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/* Check limits. */
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if (new_sorted < 0)
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new_sorted = rinfo[0].rev_index;
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else if (new_sorted >= n_bitrates)
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new_sorted = rinfo[n_bitrates - 1].rev_index;
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tmp = new_sorted;
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if (adj < 0) {
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/* Ensure that the rate decrease isn't disadvantageous. */
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for (probe = cur_sorted; probe >= new_sorted; probe--)
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if (rinfo[probe].diff <= rinfo[cur_sorted].diff &&
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rate_supported(sta, band, rinfo[probe].index))
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tmp = probe;
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} else {
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/* Look for rate increase with zero (or below) cost. */
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for (probe = new_sorted + 1; probe < n_bitrates; probe++)
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if (rinfo[probe].diff <= rinfo[new_sorted].diff &&
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rate_supported(sta, band, rinfo[probe].index))
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tmp = probe;
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}
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/* Fit the rate found to the nearest supported rate. */
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do {
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if (rate_supported(sta, band, rinfo[tmp].index)) {
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spinfo->txrate_idx = rinfo[tmp].index;
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break;
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}
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if (adj < 0)
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tmp--;
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else
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tmp++;
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} while (tmp < n_bitrates && tmp >= 0);
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#ifdef CONFIG_MAC80211_DEBUGFS
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rate_control_pid_event_rate_change(&spinfo->events,
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spinfo->txrate_idx,
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sband->bitrates[spinfo->txrate_idx].bitrate);
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#endif
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}
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/* Normalize the failed frames per-rate differences. */
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static void rate_control_pid_normalize(struct rc_pid_info *pinfo, int l)
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{
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int i, norm_offset = pinfo->norm_offset;
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struct rc_pid_rateinfo *r = pinfo->rinfo;
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if (r[0].diff > norm_offset)
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r[0].diff -= norm_offset;
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else if (r[0].diff < -norm_offset)
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r[0].diff += norm_offset;
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for (i = 0; i < l - 1; i++)
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if (r[i + 1].diff > r[i].diff + norm_offset)
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r[i + 1].diff -= norm_offset;
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else if (r[i + 1].diff <= r[i].diff)
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r[i + 1].diff += norm_offset;
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}
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static void rate_control_pid_sample(struct rc_pid_info *pinfo,
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struct ieee80211_supported_band *sband,
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struct ieee80211_sta *sta,
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struct rc_pid_sta_info *spinfo)
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{
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struct rc_pid_rateinfo *rinfo = pinfo->rinfo;
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u32 pf;
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s32 err_avg;
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u32 err_prop;
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u32 err_int;
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u32 err_der;
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int adj, i, j, tmp;
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unsigned long period;
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/* In case nothing happened during the previous control interval, turn
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* the sharpening factor on. */
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period = (HZ * pinfo->sampling_period + 500) / 1000;
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if (!period)
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period = 1;
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if (jiffies - spinfo->last_sample > 2 * period)
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spinfo->sharp_cnt = pinfo->sharpen_duration;
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spinfo->last_sample = jiffies;
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/* This should never happen, but in case, we assume the old sample is
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* still a good measurement and copy it. */
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if (unlikely(spinfo->tx_num_xmit == 0))
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pf = spinfo->last_pf;
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else {
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/* XXX: BAD HACK!!! */
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struct sta_info *si = container_of(sta, struct sta_info, sta);
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pf = spinfo->tx_num_failed * 100 / spinfo->tx_num_xmit;
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if (ieee80211_vif_is_mesh(&si->sdata->vif) && pf == 100)
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mesh_plink_broken(si);
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pf <<= RC_PID_ARITH_SHIFT;
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si->fail_avg = ((pf + (spinfo->last_pf << 3)) / 9)
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>> RC_PID_ARITH_SHIFT;
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}
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spinfo->tx_num_xmit = 0;
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spinfo->tx_num_failed = 0;
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/* If we just switched rate, update the rate behaviour info. */
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if (pinfo->oldrate != spinfo->txrate_idx) {
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i = rinfo[pinfo->oldrate].rev_index;
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j = rinfo[spinfo->txrate_idx].rev_index;
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tmp = (pf - spinfo->last_pf);
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tmp = RC_PID_DO_ARITH_RIGHT_SHIFT(tmp, RC_PID_ARITH_SHIFT);
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rinfo[j].diff = rinfo[i].diff + tmp;
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pinfo->oldrate = spinfo->txrate_idx;
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}
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rate_control_pid_normalize(pinfo, sband->n_bitrates);
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/* Compute the proportional, integral and derivative errors. */
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err_prop = (pinfo->target << RC_PID_ARITH_SHIFT) - pf;
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err_avg = spinfo->err_avg_sc >> pinfo->smoothing_shift;
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spinfo->err_avg_sc = spinfo->err_avg_sc - err_avg + err_prop;
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err_int = spinfo->err_avg_sc >> pinfo->smoothing_shift;
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err_der = (pf - spinfo->last_pf) *
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(1 + pinfo->sharpen_factor * spinfo->sharp_cnt);
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spinfo->last_pf = pf;
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if (spinfo->sharp_cnt)
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spinfo->sharp_cnt--;
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#ifdef CONFIG_MAC80211_DEBUGFS
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rate_control_pid_event_pf_sample(&spinfo->events, pf, err_prop, err_int,
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err_der);
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#endif
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/* Compute the controller output. */
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adj = (err_prop * pinfo->coeff_p + err_int * pinfo->coeff_i
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+ err_der * pinfo->coeff_d);
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adj = RC_PID_DO_ARITH_RIGHT_SHIFT(adj, 2 * RC_PID_ARITH_SHIFT);
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/* Change rate. */
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if (adj)
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rate_control_pid_adjust_rate(sband, sta, spinfo, adj, rinfo);
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}
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static void rate_control_pid_tx_status(void *priv, struct ieee80211_supported_band *sband,
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struct ieee80211_sta *sta, void *priv_sta,
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struct sk_buff *skb)
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{
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struct rc_pid_info *pinfo = priv;
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struct rc_pid_sta_info *spinfo = priv_sta;
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unsigned long period;
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struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
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if (!spinfo)
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return;
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/* Ignore all frames that were sent with a different rate than the rate
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* we currently advise mac80211 to use. */
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if (info->status.rates[0].idx != spinfo->txrate_idx)
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return;
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spinfo->tx_num_xmit++;
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#ifdef CONFIG_MAC80211_DEBUGFS
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rate_control_pid_event_tx_status(&spinfo->events, info);
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#endif
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/* We count frames that totally failed to be transmitted as two bad
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* frames, those that made it out but had some retries as one good and
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* one bad frame. */
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if (!(info->flags & IEEE80211_TX_STAT_ACK)) {
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spinfo->tx_num_failed += 2;
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spinfo->tx_num_xmit++;
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} else if (info->status.rates[0].count > 1) {
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spinfo->tx_num_failed++;
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spinfo->tx_num_xmit++;
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}
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/* Update PID controller state. */
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period = (HZ * pinfo->sampling_period + 500) / 1000;
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if (!period)
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period = 1;
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if (time_after(jiffies, spinfo->last_sample + period))
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rate_control_pid_sample(pinfo, sband, sta, spinfo);
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}
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static void
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rate_control_pid_get_rate(void *priv, struct ieee80211_sta *sta,
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void *priv_sta,
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struct ieee80211_tx_rate_control *txrc)
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{
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struct sk_buff *skb = txrc->skb;
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struct ieee80211_supported_band *sband = txrc->sband;
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struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
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struct rc_pid_sta_info *spinfo = priv_sta;
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int rateidx;
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if (txrc->rts)
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info->control.rates[0].count =
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txrc->hw->conf.long_frame_max_tx_count;
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else
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info->control.rates[0].count =
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txrc->hw->conf.short_frame_max_tx_count;
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/* Send management frames and NO_ACK data using lowest rate. */
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if (rate_control_send_low(sta, priv_sta, txrc))
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return;
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rateidx = spinfo->txrate_idx;
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if (rateidx >= sband->n_bitrates)
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rateidx = sband->n_bitrates - 1;
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info->control.rates[0].idx = rateidx;
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#ifdef CONFIG_MAC80211_DEBUGFS
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rate_control_pid_event_tx_rate(&spinfo->events,
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rateidx, sband->bitrates[rateidx].bitrate);
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#endif
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}
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static void
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rate_control_pid_rate_init(void *priv, struct ieee80211_supported_band *sband,
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struct ieee80211_sta *sta, void *priv_sta)
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{
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struct rc_pid_sta_info *spinfo = priv_sta;
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struct rc_pid_info *pinfo = priv;
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struct rc_pid_rateinfo *rinfo = pinfo->rinfo;
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struct sta_info *si;
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int i, j, tmp;
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bool s;
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/* TODO: This routine should consider using RSSI from previous packets
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* as we need to have IEEE 802.1X auth succeed immediately after assoc..
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* Until that method is implemented, we will use the lowest supported
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* rate as a workaround. */
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/* Sort the rates. This is optimized for the most common case (i.e.
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* almost-sorted CCK+OFDM rates). Kind of bubble-sort with reversed
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* mapping too. */
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for (i = 0; i < sband->n_bitrates; i++) {
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rinfo[i].index = i;
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rinfo[i].rev_index = i;
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if (RC_PID_FAST_START)
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rinfo[i].diff = 0;
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else
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rinfo[i].diff = i * pinfo->norm_offset;
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}
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for (i = 1; i < sband->n_bitrates; i++) {
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s = 0;
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for (j = 0; j < sband->n_bitrates - i; j++)
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if (unlikely(sband->bitrates[rinfo[j].index].bitrate >
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sband->bitrates[rinfo[j + 1].index].bitrate)) {
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tmp = rinfo[j].index;
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rinfo[j].index = rinfo[j + 1].index;
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rinfo[j + 1].index = tmp;
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rinfo[rinfo[j].index].rev_index = j;
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rinfo[rinfo[j + 1].index].rev_index = j + 1;
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s = 1;
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}
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if (!s)
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break;
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}
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spinfo->txrate_idx = rate_lowest_index(sband, sta);
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/* HACK */
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si = container_of(sta, struct sta_info, sta);
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si->fail_avg = 0;
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}
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static void *rate_control_pid_alloc(struct ieee80211_hw *hw,
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struct dentry *debugfsdir)
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{
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struct rc_pid_info *pinfo;
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struct rc_pid_rateinfo *rinfo;
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struct ieee80211_supported_band *sband;
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int i, max_rates = 0;
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#ifdef CONFIG_MAC80211_DEBUGFS
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struct rc_pid_debugfs_entries *de;
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#endif
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pinfo = kmalloc(sizeof(*pinfo), GFP_ATOMIC);
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if (!pinfo)
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return NULL;
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for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
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sband = hw->wiphy->bands[i];
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if (sband && sband->n_bitrates > max_rates)
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max_rates = sband->n_bitrates;
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}
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rinfo = kmalloc(sizeof(*rinfo) * max_rates, GFP_ATOMIC);
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if (!rinfo) {
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kfree(pinfo);
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return NULL;
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}
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pinfo->target = RC_PID_TARGET_PF;
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pinfo->sampling_period = RC_PID_INTERVAL;
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pinfo->coeff_p = RC_PID_COEFF_P;
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pinfo->coeff_i = RC_PID_COEFF_I;
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pinfo->coeff_d = RC_PID_COEFF_D;
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pinfo->smoothing_shift = RC_PID_SMOOTHING_SHIFT;
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pinfo->sharpen_factor = RC_PID_SHARPENING_FACTOR;
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pinfo->sharpen_duration = RC_PID_SHARPENING_DURATION;
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pinfo->norm_offset = RC_PID_NORM_OFFSET;
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pinfo->rinfo = rinfo;
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pinfo->oldrate = 0;
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#ifdef CONFIG_MAC80211_DEBUGFS
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de = &pinfo->dentries;
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de->target = debugfs_create_u32("target_pf", S_IRUSR | S_IWUSR,
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debugfsdir, &pinfo->target);
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de->sampling_period = debugfs_create_u32("sampling_period",
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S_IRUSR | S_IWUSR, debugfsdir,
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&pinfo->sampling_period);
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de->coeff_p = debugfs_create_u32("coeff_p", S_IRUSR | S_IWUSR,
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debugfsdir, (u32 *)&pinfo->coeff_p);
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de->coeff_i = debugfs_create_u32("coeff_i", S_IRUSR | S_IWUSR,
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debugfsdir, (u32 *)&pinfo->coeff_i);
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de->coeff_d = debugfs_create_u32("coeff_d", S_IRUSR | S_IWUSR,
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debugfsdir, (u32 *)&pinfo->coeff_d);
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de->smoothing_shift = debugfs_create_u32("smoothing_shift",
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S_IRUSR | S_IWUSR, debugfsdir,
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&pinfo->smoothing_shift);
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de->sharpen_factor = debugfs_create_u32("sharpen_factor",
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S_IRUSR | S_IWUSR, debugfsdir,
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&pinfo->sharpen_factor);
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de->sharpen_duration = debugfs_create_u32("sharpen_duration",
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S_IRUSR | S_IWUSR, debugfsdir,
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&pinfo->sharpen_duration);
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de->norm_offset = debugfs_create_u32("norm_offset",
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S_IRUSR | S_IWUSR, debugfsdir,
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&pinfo->norm_offset);
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#endif
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return pinfo;
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}
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static void rate_control_pid_free(void *priv)
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{
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struct rc_pid_info *pinfo = priv;
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#ifdef CONFIG_MAC80211_DEBUGFS
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struct rc_pid_debugfs_entries *de = &pinfo->dentries;
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debugfs_remove(de->norm_offset);
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debugfs_remove(de->sharpen_duration);
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debugfs_remove(de->sharpen_factor);
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debugfs_remove(de->smoothing_shift);
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debugfs_remove(de->coeff_d);
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debugfs_remove(de->coeff_i);
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debugfs_remove(de->coeff_p);
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debugfs_remove(de->sampling_period);
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debugfs_remove(de->target);
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#endif
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kfree(pinfo->rinfo);
|
|
kfree(pinfo);
|
|
}
|
|
|
|
static void *rate_control_pid_alloc_sta(void *priv, struct ieee80211_sta *sta,
|
|
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, struct ieee80211_sta *sta,
|
|
void *priv_sta)
|
|
{
|
|
kfree(priv_sta);
|
|
}
|
|
|
|
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,
|
|
.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
|
|
};
|
|
|
|
int __init rc80211_pid_init(void)
|
|
{
|
|
return ieee80211_rate_control_register(&mac80211_rcpid);
|
|
}
|
|
|
|
void rc80211_pid_exit(void)
|
|
{
|
|
ieee80211_rate_control_unregister(&mac80211_rcpid);
|
|
}
|