diff options
| -rw-r--r-- | net/mac80211/rc80211_pid_algo.c | 92 |
1 files changed, 43 insertions, 49 deletions
diff --git a/net/mac80211/rc80211_pid_algo.c b/net/mac80211/rc80211_pid_algo.c index c339571632b2..3b77410588e7 100644 --- a/net/mac80211/rc80211_pid_algo.c +++ b/net/mac80211/rc80211_pid_algo.c @@ -2,7 +2,7 @@ * Copyright 2002-2005, Instant802 Networks, Inc. * Copyright 2005, Devicescape Software, Inc. * Copyright 2007, Mattias Nissler <mattias.nissler@gmx.de> - * Copyright 2007, Stefano Brivio <stefano.brivio@polimi.it> + * Copyright 2007-2008, 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 @@ -63,72 +63,66 @@ * RC_PID_ARITH_SHIFT. */ - -/* Shift the adjustment so that we won't switch to a lower rate if it exhibited - * a worse failed frames behaviour and we'll choose the highest rate whose - * failed frames behaviour is not worse than the one of the original rate - * target. While at it, check that the adjustment is within the ranges. Then, - * provide the new rate index. */ -static int rate_control_pid_shift_adjust(struct rc_pid_rateinfo *r, - int adj, int cur, int l) -{ - int i, j, k, tmp; - - j = r[cur].rev_index; - i = j + adj; - - if (i < 0) - return r[0].index; - if (i >= l - 1) - return r[l - 1].index; - - tmp = i; - - if (adj < 0) { - for (k = j; k >= i; k--) - if (r[k].diff <= r[j].diff) - tmp = k; - } else { - for (k = i + 1; k + i < l; k++) - if (r[k].diff <= r[i].diff) - tmp = k; - } - - return r[tmp].index; -} - +/* Adjust the rate while ensuring that we won't switch to a lower rate if it + * exhibited a worse failed frames behaviour and we'll choose the highest rate + * whose failed frames behaviour is not worse than the one of the original rate + * target. While at it, check that the new rate is valid. */ static void rate_control_pid_adjust_rate(struct ieee80211_local *local, struct sta_info *sta, int adj, struct rc_pid_rateinfo *rinfo) { struct ieee80211_sub_if_data *sdata; struct ieee80211_hw_mode *mode; - int newidx; - int maxrate; - int back = (adj > 0) ? 1 : -1; + int cur_sorted, new_sorted, probe, tmp, n_bitrates; + int cur = sta->txrate; sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev); mode = local->oper_hw_mode; - maxrate = sdata->bss ? sdata->bss->max_ratectrl_rateidx : -1; + n_bitrates = mode->num_rates; - newidx = rate_control_pid_shift_adjust(rinfo, adj, sta->txrate, - mode->num_rates); + /* Map passed arguments to sorted values. */ + cur_sorted = rinfo[cur].rev_index; + new_sorted = cur_sorted + adj; - while (newidx != sta->txrate) { - if (rate_supported(sta, mode, newidx) && - (maxrate < 0 || newidx <= maxrate)) { - sta->txrate = newidx; - break; - } + /* Check limits. */ + if (new_sorted < 0) + new_sorted = rinfo[0].rev_index; + else if (new_sorted >= n_bitrates) + new_sorted = rinfo[n_bitrates - 1].rev_index; - newidx += back; + tmp = new_sorted; + + if (adj < 0) { + /* Ensure that the rate decrease isn't disadvantageous. */ + for (probe = cur_sorted; probe >= new_sorted; probe--) + if (rinfo[probe].diff <= rinfo[cur_sorted].diff && + rate_supported(sta, mode, rinfo[probe].index)) + tmp = probe; + } else { + /* Look for rate increase with zero (or below) cost. */ + for (probe = new_sorted + 1; probe < n_bitrates; probe++) + if (rinfo[probe].diff <= rinfo[new_sorted].diff && + rate_supported(sta, mode, rinfo[probe].index)) + tmp = probe; } + /* Fit the rate found to the nearest supported rate. */ + do { + if (rate_supported(sta, mode, rinfo[tmp].index)) { + sta->txrate = rinfo[tmp].index; + break; + } + if (adj < 0) + tmp--; + else + tmp++; + } while (tmp < n_bitrates && tmp >= 0); + #ifdef CONFIG_MAC80211_DEBUGFS rate_control_pid_event_rate_change( &((struct rc_pid_sta_info *)sta->rate_ctrl_priv)->events, - newidx, mode->rates[newidx].rate); + cur, mode->rates[cur].rate); #endif } |