From c78311b598b0ee2a627082800e70ede89e3b6e70 Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd@openwrt.org>
Date: Tue, 22 Apr 2008 23:35:27 +0000
Subject: madwifi: put an upper limit on the amount of sampling that minstrel
 should do when the link changes its status from very good to slightly bad.
 the previous version of the patch could have resulted in erratic rate control
 behavior when there was a lot of sampling backlog.

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@10921 3c298f89-4303-0410-b956-a3cf2f4a3e73
---
 .../madwifi/patches/345-minstrel_sampling.patch    | 36 ++++++++++++++--------
 1 file changed, 24 insertions(+), 12 deletions(-)

diff --git a/package/madwifi/patches/345-minstrel_sampling.patch b/package/madwifi/patches/345-minstrel_sampling.patch
index ea4c25f3ad..3be5a8fee3 100644
--- a/package/madwifi/patches/345-minstrel_sampling.patch
+++ b/package/madwifi/patches/345-minstrel_sampling.patch
@@ -1,7 +1,7 @@
 Index: madwifi-trunk-r3314/ath/if_ath.c
 ===================================================================
---- madwifi-trunk-r3314.orig/ath/if_ath.c	2008-04-21 02:44:23.000000000 +0200
-+++ madwifi-trunk-r3314/ath/if_ath.c	2008-04-21 03:33:02.000000000 +0200
+--- madwifi-trunk-r3314.orig/ath/if_ath.c	2008-04-21 09:13:19.000000000 +0200
++++ madwifi-trunk-r3314/ath/if_ath.c	2008-04-23 01:15:49.000000000 +0200
 @@ -8095,6 +8095,7 @@
  		ath_hal_setupxtxdesc(sc->sc_ah, ds, mrr.rate1, mrr.retries1,
  				     mrr.rate2, mrr.retries2,
@@ -12,8 +12,8 @@ Index: madwifi-trunk-r3314/ath/if_ath.c
  #ifndef ATH_SUPERG_FF
 Index: madwifi-trunk-r3314/ath/if_athvar.h
 ===================================================================
---- madwifi-trunk-r3314.orig/ath/if_athvar.h	2008-04-21 00:50:13.000000000 +0200
-+++ madwifi-trunk-r3314/ath/if_athvar.h	2008-04-21 03:31:48.000000000 +0200
+--- madwifi-trunk-r3314.orig/ath/if_athvar.h	2008-04-21 09:13:19.000000000 +0200
++++ madwifi-trunk-r3314/ath/if_athvar.h	2008-04-23 01:15:49.000000000 +0200
 @@ -446,6 +446,7 @@
  	u_int16_t bf_flags;				/* tx descriptor flags */
  	u_int64_t bf_tsf;
@@ -24,18 +24,30 @@ Index: madwifi-trunk-r3314/ath/if_athvar.h
  	 *      multiple segments.
 Index: madwifi-trunk-r3314/ath_rate/minstrel/minstrel.c
 ===================================================================
---- madwifi-trunk-r3314.orig/ath_rate/minstrel/minstrel.c	2008-04-21 02:50:31.000000000 +0200
-+++ madwifi-trunk-r3314/ath_rate/minstrel/minstrel.c	2008-04-21 04:08:36.000000000 +0200
-@@ -336,7 +336,7 @@
+--- madwifi-trunk-r3314.orig/ath_rate/minstrel/minstrel.c	2008-04-21 09:13:19.000000000 +0200
++++ madwifi-trunk-r3314/ath_rate/minstrel/minstrel.c	2008-04-23 01:15:50.000000000 +0200
+@@ -333,15 +333,19 @@
+ 		if (sn->static_rate_ndx >= 0) {
+ 			    ndx = sn->static_rate_ndx;
+ 		} else {
++			int delta;
  			sn->packet_count++;
  			sn->random_n = (sn->a * sn->random_n) + sn->b;
  			offset = sn->random_n & 0xf;
 -			if ((((100 * sn->sample_count) / (sn->sample_count + sn->packet_count)) < ath_lookaround_rate) && (offset < 2)) {
-+			if ((((100 * sn->sample_count) / (sn->packet_count ?: 1)) < ath_lookaround_rate) && (offset < 2)) {
++			delta = (sn->packet_count * ath_lookaround_rate / 100) - sn->sample_count;
++			if ((delta > 0) && (offset < 2)) {
  				sn->sample_count++;
  				sn->is_sampling = 1;
  				if (sn->packet_count >= 10000) {
-@@ -398,11 +398,14 @@
+ 					sn->sample_count = 0;
+ 					sn->packet_count = 0;
++				} else if (delta > sn->num_rates * 2) {
++					sn->sample_count += ((delta - sn->num_rates * 2) * ath_lookaround_rate) / 100;
+ 				}
+ 
+ 				/* Don't look for slowest rate (i.e. slowest
+@@ -398,11 +402,14 @@
  		if (sn->num_rates <= 0)
  			return;
  
@@ -52,7 +64,7 @@ Index: madwifi-trunk-r3314/ath_rate/minstrel/minstrel.c
  				rc1 = sn->max_tp_rate;
  		} else {
  			rc1 = sn->max_tp_rate2;
-@@ -525,6 +528,9 @@
+@@ -525,6 +532,9 @@
  		if (tries <= tries1)
  			return;
  
@@ -64,8 +76,8 @@ Index: madwifi-trunk-r3314/ath_rate/minstrel/minstrel.c
  		tries = tries - tries1;
 Index: madwifi-trunk-r3314/net80211/ieee80211_rate.h
 ===================================================================
---- madwifi-trunk-r3314.orig/net80211/ieee80211_rate.h	2008-01-31 03:29:42.000000000 +0100
-+++ madwifi-trunk-r3314/net80211/ieee80211_rate.h	2008-04-21 03:30:25.000000000 +0200
+--- madwifi-trunk-r3314.orig/net80211/ieee80211_rate.h	2008-04-21 09:11:19.000000000 +0200
++++ madwifi-trunk-r3314/net80211/ieee80211_rate.h	2008-04-21 09:13:19.000000000 +0200
 @@ -87,6 +87,7 @@
  	int retries2;
  	int rate3;
-- 
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