| Message ID | 1362422905-78079-6-git-send-email-thomas@net.t-labs.tu-berlin.de (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On 2013-03-04 7:48 PM, Thomas Huehn wrote: > While minstrel bootstraps and fills the success probabilities of each > rate the lowest rate has typically a very high success probability > (often 100% in our tests). > Its statistics are never updated but considered to setup the mrr chain. > In our tests we see that especially the 3rd mrr stage (which is that > rate providing highest success probability) is filled with the lowest rate > because its initial high sucess probability is never updated. By design > the 4th mrr stage is filled with the lowest rate so often 3rd and 4th > mrr stage are equal. > > This patch follows minstrels general approach of assuming as little > as possible about rate dependencies. Consequently we include the > lowest rate into the random sampling table to get balanced up-to-date > statistics of all rates and therefore balanced decisions. > > Signed-off-by: Thomas Huehn <thomas@net.t-labs.tu-berlin.de> > --- > net/mac80211/rc80211_minstrel.c | 20 +++++++------------- > net/mac80211/rc80211_minstrel.h | 4 +++- > net/mac80211/rc80211_minstrel_ht.c | 1 - > 3 files changed, 10 insertions(+), 15 deletions(-) > > diff --git a/net/mac80211/rc80211_minstrel.c b/net/mac80211/rc80211_minstrel.c > index aa59f29..aa1e81a 100644 > --- a/net/mac80211/rc80211_minstrel.c > +++ b/net/mac80211/rc80211_minstrel.c > @@ -370,26 +369,21 @@ static void > init_sample_table(struct minstrel_sta_info *mi) > { > unsigned int i, col, new_idx; > - unsigned int n_srates = mi->n_rates - 1; > u8 rnd[8]; > > mi->sample_column = 0; > mi->sample_row = 0; > - memset(mi->sample_table, 0, SAMPLE_COLUMNS * mi->n_rates); > + memset(mi->sample_table, 0xff, SAMPLE_COLUMNS * mi->n_rates); > > for (col = 0; col < SAMPLE_COLUMNS; col++) { > - for (i = 0; i < n_srates; i++) { > + for (i = 0; i < mi->n_rates; i++) { > get_random_bytes(rnd, sizeof(rnd)); > - new_idx = (i + rnd[i & 7]) % n_srates; > + new_idx = (i + rnd[i]) % mi->n_rates; Don't remove the '& 7' part, otherwise the rnd array will overflow. There's no need for it to be as big as the number of rates though. Also, there's a typo in the subject line: 'randmon'. - Felix -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/mac80211/rc80211_minstrel.c b/net/mac80211/rc80211_minstrel.c index aa59f29..aa1e81a 100644 --- a/net/mac80211/rc80211_minstrel.c +++ b/net/mac80211/rc80211_minstrel.c @@ -55,7 +55,6 @@ #include "rate.h" #include "rc80211_minstrel.h" -#define SAMPLE_COLUMNS 10 #define SAMPLE_TBL(_mi, _idx, _col) \ _mi->sample_table[(_idx * SAMPLE_COLUMNS) + _col] @@ -210,7 +209,7 @@ minstrel_get_next_sample(struct minstrel_sta_info *mi) unsigned int sample_ndx; sample_ndx = SAMPLE_TBL(mi, mi->sample_row, mi->sample_column); mi->sample_row++; - if ((int) mi->sample_row > (mi->n_rates - 2)) { + if ((int) mi->sample_row >= mi->n_rates) { mi->sample_row = 0; mi->sample_column++; if (mi->sample_column >= SAMPLE_COLUMNS) @@ -370,26 +369,21 @@ static void init_sample_table(struct minstrel_sta_info *mi) { unsigned int i, col, new_idx; - unsigned int n_srates = mi->n_rates - 1; u8 rnd[8]; mi->sample_column = 0; mi->sample_row = 0; - memset(mi->sample_table, 0, SAMPLE_COLUMNS * mi->n_rates); + memset(mi->sample_table, 0xff, SAMPLE_COLUMNS * mi->n_rates); for (col = 0; col < SAMPLE_COLUMNS; col++) { - for (i = 0; i < n_srates; i++) { + for (i = 0; i < mi->n_rates; i++) { get_random_bytes(rnd, sizeof(rnd)); - new_idx = (i + rnd[i & 7]) % n_srates; + new_idx = (i + rnd[i]) % mi->n_rates; - while (SAMPLE_TBL(mi, new_idx, col) != 0) - new_idx = (new_idx + 1) % n_srates; + while (SAMPLE_TBL(mi, new_idx, col) != 0xff) + new_idx = (new_idx + 1) % mi->n_rates; - /* Don't sample the slowest rate (i.e. slowest base - * rate). We must presume that the slowest rate works - * fine, or else other management frames will also be - * failing and the link will break */ - SAMPLE_TBL(mi, new_idx, col) = i + 1; + SAMPLE_TBL(mi, new_idx, col) = i; } } } diff --git a/net/mac80211/rc80211_minstrel.h b/net/mac80211/rc80211_minstrel.h index 200b7e3..a0ccc57 100644 --- a/net/mac80211/rc80211_minstrel.h +++ b/net/mac80211/rc80211_minstrel.h @@ -9,7 +9,9 @@ #ifndef __RC_MINSTREL_H #define __RC_MINSTREL_H -#define EWMA_LEVEL 75 /* ewma weighting factor [%] */ +#define EWMA_LEVEL 75 /* ewma weighting factor [%] */ +#define SAMPLE_COLUMNS 10 /* number of columns in sample table */ + /* scaled fraction values */ #define MINSTREL_SCALE 16 diff --git a/net/mac80211/rc80211_minstrel_ht.c b/net/mac80211/rc80211_minstrel_ht.c index a3081e5..8f88108 100644 --- a/net/mac80211/rc80211_minstrel_ht.c +++ b/net/mac80211/rc80211_minstrel_ht.c @@ -17,7 +17,6 @@ #include "rc80211_minstrel_ht.h" #define AVG_PKT_SIZE 1200 -#define SAMPLE_COLUMNS 10 /* Number of bits for an average sized packet */ #define MCS_NBITS (AVG_PKT_SIZE << 3)
While minstrel bootstraps and fills the success probabilities of each rate the lowest rate has typically a very high success probability (often 100% in our tests). Its statistics are never updated but considered to setup the mrr chain. In our tests we see that especially the 3rd mrr stage (which is that rate providing highest success probability) is filled with the lowest rate because its initial high sucess probability is never updated. By design the 4th mrr stage is filled with the lowest rate so often 3rd and 4th mrr stage are equal. This patch follows minstrels general approach of assuming as little as possible about rate dependencies. Consequently we include the lowest rate into the random sampling table to get balanced up-to-date statistics of all rates and therefore balanced decisions. Signed-off-by: Thomas Huehn <thomas@net.t-labs.tu-berlin.de> --- net/mac80211/rc80211_minstrel.c | 20 +++++++------------- net/mac80211/rc80211_minstrel.h | 4 +++- net/mac80211/rc80211_minstrel_ht.c | 1 - 3 files changed, 10 insertions(+), 15 deletions(-)