diff options
| author | Stefano Brivio <stefano.brivio@polimi.it> | 2007-12-19 01:26:52 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2008-01-28 14:59:43 -0800 |
| commit | 1dc4d1e6a1e81fee0d488cec4fcd39269ec51318 (patch) | |
| tree | 5417b8c837ce881883e3c8a9c7ff62b972cb9a16 /net | |
| parent | 90d501d610c0065dce43120c26744a49d8e0490c (diff) | |
| download | linux-1dc4d1e6a1e81fee0d488cec4fcd39269ec51318.tar.bz2 | |
rc80211-pid: add sharpening factor
This patch introduces a PID sharpening factor for faster response after
association and low activity events.
Signed-off-by: Stefano Brivio <stefano.brivio@polimi.it>
Signed-off-by: Mattias Nissler <mattias.nissler@gmx.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/mac80211/rc80211_pid.c | 35 |
1 files changed, 27 insertions, 8 deletions
diff --git a/net/mac80211/rc80211_pid.c b/net/mac80211/rc80211_pid.c index 1116dc67ddd0..7f8cf27ad2f9 100644 --- a/net/mac80211/rc80211_pid.c +++ b/net/mac80211/rc80211_pid.c @@ -23,13 +23,16 @@ * * The controller basically computes the following: * - * adj = CP * err + CI * err_avg + CD * (err - last_err) + * adj = CP * err + CI * err_avg + CD * (err - last_err) * (1 + sharpening) * * where * adj adjustment value that is used to switch TX rate (see below) * err current error: target vs. current failed frames percentage * last_err last error * err_avg average (i.e. poor man's integral) of recent errors + * sharpening non-zero when fast response is needed (i.e. right after + * association or no frames sent for a long time), heading + * to zero over time * CP Proportional coefficient * CI Integral coefficient * CD Derivative coefficient @@ -65,6 +68,10 @@ #define RC_PID_SMOOTHING_SHIFT 3 #define RC_PID_SMOOTHING (1 << RC_PID_SMOOTHING_SHIFT) +/* Sharpening factor (used for D part of PID controller) */ +#define RC_PID_SHARPENING_FACTOR 0 +#define RC_PID_SHARPENING_DURATION 0 + /* Fixed point arithmetic shifting amount. */ #define RC_PID_ARITH_SHIFT 8 @@ -131,8 +138,11 @@ struct rc_pid_sta_info { */ s32 err_avg_sc; - /* Last framed failes percentage sample */ + /* Last framed failes percentage sample. */ u32 last_pf; + + /* Sharpening needed. */ + u8 sharp_cnt; }; /* Algorithm parameters. We keep them on a per-algorithm approach, so they can @@ -267,20 +277,26 @@ static void rate_control_pid_sample(struct rc_pid_info *pinfo, mode = local->oper_hw_mode; spinfo = sta->rate_ctrl_priv; + + /* In case nothing happened during the previous control interval, turn + * the sharpening factor on. */ + if (jiffies - spinfo->last_sample > 2 * RC_PID_INTERVAL) + spinfo->sharp_cnt = RC_PID_SHARPENING_DURATION; + spinfo->last_sample = jiffies; - /* If no frames were transmitted, we assume the old sample is + /* This should never happen, but in case, we assume the old sample is * still a good measurement and copy it. */ - if (spinfo->tx_num_xmit == 0) + if (unlikely(spinfo->tx_num_xmit == 0)) pf = spinfo->last_pf; else { pf = spinfo->tx_num_failed * 100 / spinfo->tx_num_xmit; pf <<= RC_PID_ARITH_SHIFT; - - spinfo->tx_num_xmit = 0; - spinfo->tx_num_failed = 0; } + spinfo->tx_num_xmit = 0; + spinfo->tx_num_failed = 0; + /* If we just switched rate, update the rate behaviour info. */ if (pinfo->oldrate != sta->txrate) { @@ -302,8 +318,11 @@ static void rate_control_pid_sample(struct rc_pid_info *pinfo, spinfo->err_avg_sc = spinfo->err_avg_sc - err_avg + err_prop; err_int = spinfo->err_avg_sc >> RC_PID_SMOOTHING_SHIFT; - err_der = pf - spinfo->last_pf; + err_der = pf - spinfo->last_pf + * (1 + RC_PID_SHARPENING_FACTOR * spinfo->sharp_cnt); spinfo->last_pf = pf; + if (spinfo->sharp_cnt) + spinfo->sharp_cnt--; /* Compute the controller output. */ adj = (err_prop * pinfo->coeff_p + err_int * pinfo->coeff_i |