PERFORCE change 140816 for review

[Sam Leffler]

http://perforce.freebsd.org/chv.cgi?CH=140816

Change 140816 by sam at sam_ebb on 2008/04/28 22:53:17

	o lie to amrr about retry counts to avoid pessmimizing the rate
	  estimator; this is mostly to compensate for bb issues but also
	  papers over the generic amrr algorithm only handling a single
	  tx rate (and we often supply two)
	o simplify tb_rate data recorded by tx complete status processing;
	  we don't need the rate indices, the rates are sufficient and
	  less work to acquire; also no need to bzero values we always write

Affected files ...

.. //depot/projects/vap/sys/dev/bwi/if_bwi.c#10 edit
.. //depot/projects/vap/sys/dev/bwi/if_bwivar.h#6 edit

Differences ...

==== //depot/projects/vap/sys/dev/bwi/if_bwi.c#10 (text+ko) ====

@@ -2942,7 +2942,7 @@
 	uint32_t mac_ctrl;
 	uint16_t phy_ctrl;
 	bus_addr_t paddr;
-	int type, ismcast, pkt_len, error;
+	int type, ismcast, pkt_len, error, rix;
 #if 0
 	const uint8_t *p;
 	int i;
@@ -2962,7 +2962,6 @@
 	/*
 	 * Find TX rate
 	 */
-	bzero(tb->tb_rate_idx, sizeof(tb->tb_rate_idx));
 	tp = &vap->iv_txparms[ieee80211_chan2mode(ic->ic_curchan)];
 	if (type != IEEE80211_FC0_TYPE_DATA || (m->m_flags & M_EAPOL)) {
 		rate = rate_fb = tp->mgmtrate;
@@ -2971,19 +2970,18 @@
 	} else if (tp->ucastrate != IEEE80211_FIXED_RATE_NONE) {
 		rate = rate_fb = tp->ucastrate;
 	} else {
-		tb->tb_rate_idx[0] =
-		    ieee80211_amrr_choose(ni, &BWI_NODE(ni)->amn);
+		rix = ieee80211_amrr_choose(ni, &BWI_NODE(ni)->amn);
 		rate = ni->ni_txrate;
 
-		if (tb->tb_rate_idx[0] > 0) {
-			tb->tb_rate_idx[1] = tb->tb_rate_idx[0] - 1;
-			rate_fb = ni->ni_rates.rs_rates[tb->tb_rate_idx[1]] &
+		if (rix > 0) {
+			rate_fb = ni->ni_rates.rs_rates[rix-1] &
 				  IEEE80211_RATE_VAL;
 		} else {
 			rate_fb = rate;
-			tb->tb_rate_idx[1] = tb->tb_rate_idx[0];
 		}
 	}
+	tb->tb_rate[0] = rate;
+	tb->tb_rate[1] = rate_fb;
 	sc->sc_tx_rate = rate;
 
 	/*
@@ -3147,12 +3145,11 @@
 	/*
 	 * Find TX rate
 	 */
-	bzero(tb->tb_rate_idx, sizeof(tb->tb_rate_idx));
 	rate = params->ibp_rate0;
 	rate_fb = (params->ibp_try1 != 0) ?
 	    params->ibp_rate1 : params->ibp_rate0;
-	tb->tb_rate_idx[0] = rate;
-	tb->tb_rate_idx[1] = rate_fb;
+	tb->tb_rate[0] = rate;
+	tb->tb_rate[1] = rate_fb;
 	sc->sc_tx_rate = rate;
 
 	/*
@@ -3347,12 +3344,15 @@
 
 		/* NB: update rate control only for unicast frames */
 		if (hdr->txh_mac_ctrl & htole32(BWI_TXH_MAC_C_ACK)) {
-			/* Feed back 'acked and data_txcnt' */
-			ieee80211_amrr_tx_complete(&bn->amn,
-			   (acked &&
-			    (data_txcnt <= BWI_SHRETRY_FB ||
-			     tb->tb_rate_idx[0] == tb->tb_rate_idx[1])),
-			   data_txcnt-1);
+			/*
+			 * Feed back 'acked and data_txcnt'.  Note that the
+			 * generic AMRR code only understands one tx rate
+			 * and the estimator doesn't handle real retry counts
+			 * well so to avoid over-aggressive downshifting we
+			 * treat any number of retries as "1".
+			 */
+			ieee80211_amrr_tx_complete(&bn->amn, acked,
+			    data_txcnt > 1);
 		}
 
 		/*

==== //depot/projects/vap/sys/dev/bwi/if_bwivar.h#6 (text+ko) ====

@@ -233,7 +233,7 @@
 	bus_dmamap_t		tb_dmap;
 
 	struct ieee80211_node	*tb_ni;
-	int			tb_rate_idx[2];
+	int			tb_rate[2];
 };
 
 struct bwi_txbuf_data {