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.

SVN-Revision: 10921

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;