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authorStefano Brivio <stefano.brivio@polimi.it>2008-03-02 11:33:10 +0100
committerJohn W. Linville <linville@tuxdriver.com>2008-03-04 18:36:35 -0500
commit1d60ab0574fae362b1cca0ef52181ef75fd46832 (patch)
tree0623fff0e79c97fa8862b5657a19363c0734cfb4 /net
parentec9b6add7d81f902f6094e71f595da4a362f3348 (diff)
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rc80211-pid: fix rate adjustment
Merge rate_control_pid_shift_adjust() to rate_control_pid_adjust_rate() in order to make the learning algorithm aware of constraints on rates. Also add some comments and rename variables. This fixes a bug which prevented 802.11b/g non-AP STAs from working with 802.11b only AP STAs. This patch was originally destined for 2.6.26, and is being backported to fix a user reported problem in post-2.6.24 kernels. Signed-off-by: Stefano Brivio <stefano.brivio@polimi.it> Signed-off-by: John W. Linville <linville@tuxdriver.com>
Diffstat (limited to 'net')
-rw-r--r--net/mac80211/rc80211_pid_algo.c92
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
}