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Date: Sun, 2 Mar 2008 11:33:10 +0100
From: Stefano Brivio <stefano.brivio@...imi.it>
To: "John W. Linville" <linville@...driver.com>
Cc: Chris Clayton <chris2553@...glemail.com>, ivdoorn@...il.com,
linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org,
johannes@...solutions.net,
Mattias Nissler <mattias.nissler@....de>,
Mike Kelly <pioto@...to.org>
Subject: Re: 2.6.25-rc2 regression in rt61pci wireless driver
On Wed, 27 Feb 2008 12:25:46 -0500
"John W. Linville" <linville@...driver.com> wrote:
> That might be easier said than done. It looks like that patch depends
> on the big cfg80211 API change queued for 2.6.26.
>
> Stefano offered to rebase that on 2.6.25. Stefano, could you post
> that as part of this thread?
Sorry for the delay. This is based on 2.6.25-rc3. Please test.
---
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.
Signed-off-by: Stefano Brivio <stefano.brivio@...imi.it>
---
Index: linux-2.6.24/net/mac80211/rc80211_pid_algo.c
===================================================================
--- linux-2.6.24.orig/net/mac80211/rc80211_pid_algo.c
+++ linux-2.6.24/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@....de>
- * Copyright 2007, Stefano Brivio <stefano.brivio@...imi.it>
+ * Copyright 2007-2008, Stefano Brivio <stefano.brivio@...imi.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;
+
+ /* 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;
- while (newidx != sta->txrate) {
- if (rate_supported(sta, mode, newidx) &&
- (maxrate < 0 || newidx <= maxrate)) {
- sta->txrate = newidx;
- break;
- }
+ tmp = new_sorted;
- newidx += back;
+ 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
}
--
Ciao
Stefano
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