Date: Wed, 18 May 2011 14:02:57 +0800 From: Adrian Chadd <adrian@freebsd.org> To: freebsd-wireless@freebsd.org Subject: ath_rate_sample: only sample/try HT rates for HT nodes Message-ID: <BANLkTi=53kfqj3HLWa%2BKWEHn3rWCm7ML6Q@mail.gmail.com>
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[-- Attachment #1 --]
Hi,
The initial sample rate 11n code that I merged in from Rui didn't
properly disable the non-HT rates when sampling and choosing a rate
for a HT node.
This meant that time was spent trying to sample non-11n rates.
This patch disables this behaviour whilst leaving the non-11n rates in
the 11na/11ng TX schedules. Since the management rate in an 11na
network is a legacy rate (6mbit, not MCS0) then there will be
instances of legacy TXing occuring. If the legacy rates are simply
removed from the TX schedule, the sample rate module logs a complaint.
I'd rather this not happen.
This seems to work in legacy and non-legacy modes but I admit I
haven't given it much testing yet in 11bg and 11a modes. I'd
appreciate some testing and feedback.
Thanks!
Adrian
[-- Attachment #2 --]
Index: sample.c
===================================================================
--- sample.c (revision 221947)
+++ sample.c (working copy)
@@ -161,9 +161,10 @@
* or -1 if all the average_tx_times are 0.
*/
static __inline int
-pick_best_rate(struct sample_node *sn, const HAL_RATE_TABLE *rt,
+pick_best_rate(struct ath_node *an, const HAL_RATE_TABLE *rt,
int size_bin, int require_acked_before)
{
+ struct sample_node *sn = ATH_NODE_SAMPLE(an);
int best_rate_rix, best_rate_tt;
uint32_t mask;
int rix, tt;
@@ -174,6 +175,12 @@
if ((mask & 1) == 0) /* not a supported rate */
continue;
+ /* Don't pick a non-HT rate for a HT node */
+ if ((an->an_node.ni_flags & IEEE80211_NODE_HT) &&
+ (rt->info[rix].phy != IEEE80211_T_HT)) {
+ continue;
+ }
+
tt = sn->stats[size_bin][rix].average_tx_time;
if (tt <= 0 ||
(require_acked_before &&
@@ -196,11 +203,12 @@
* Pick a good "random" bit-rate to sample other than the current one.
*/
static __inline int
-pick_sample_rate(struct sample_softc *ssc , struct sample_node *sn,
+pick_sample_rate(struct sample_softc *ssc , struct ath_node *an,
const HAL_RATE_TABLE *rt, int size_bin)
{
#define DOT11RATE(ix) (rt->info[ix].dot11Rate & IEEE80211_RATE_VAL)
#define MCS(ix) (rt->info[ix].dot11Rate | IEEE80211_RATE_MCS)
+ struct sample_node *sn = ATH_NODE_SAMPLE(an);
int current_rix, rix;
unsigned current_tt;
uint32_t mask;
@@ -208,6 +216,7 @@
current_rix = sn->current_rix[size_bin];
if (current_rix < 0) {
/* no successes yet, send at the lowest bit-rate */
+ /* XXX should return MCS0 if HT */
return 0;
}
@@ -223,6 +232,13 @@
continue;
}
+ /* if the node is HT and the rate isn't HT, don't bother sample */
+ if ((an->an_node.ni_flags & IEEE80211_NODE_HT) &&
+ (rt->info[rix].phy != IEEE80211_T_HT)) {
+ mask &= ~(1<<rix);
+ goto nextrate;
+ }
+
/* this bit-rate is always worse than the current one */
if (sn->stats[size_bin][rix].perfect_tx_time > current_tt) {
mask &= ~(1<<rix);
@@ -236,11 +252,12 @@
goto nextrate;
}
- /* don't sample more than 2 rates higher for rates > 11M */
- if (DOT11RATE(rix) > 2*11 && rix > current_rix + 2) {
- mask &= ~(1<<rix);
- goto nextrate;
- }
+ /* don't sample more than 2 rates higher for rates > 11M for non-HT rates */
+ if (! (an->an_node.ni_flags & IEEE80211_NODE_HT))
+ if (DOT11RATE(rix) > 2*11 && rix > current_rix + 2) {
+ mask &= ~(1<<rix);
+ goto nextrate;
+ }
sn->last_sample_rix[size_bin] = rix;
return rix;
@@ -327,7 +344,7 @@
/* XXX TODO: this doesn't know about 11gn vs 11g protection; teach it */
mrr = sc->sc_mrretry && !(ic->ic_flags & IEEE80211_F_USEPROT);
- best_rix = pick_best_rate(sn, rt, size_bin, !mrr);
+ best_rix = pick_best_rate(an, rt, size_bin, !mrr);
if (best_rix >= 0) {
average_tx_time = sn->stats[size_bin][best_rix].average_tx_time;
} else {
@@ -338,7 +355,7 @@
* rates to sample_rate% of the total transmission time.
*/
if (sn->sample_tt[size_bin] < average_tx_time * (sn->packets_since_sample[size_bin]*ssc->sample_rate/100)) {
- rix = pick_sample_rate(ssc, sn, rt, size_bin);
+ rix = pick_sample_rate(ssc, an, rt, size_bin);
IEEE80211_NOTE(an->an_node.ni_vap, IEEE80211_MSG_RATECTL,
&an->an_node, "size %u sample rate %d current rate %d",
bin_to_size(size_bin), RATE(rix),
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