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Commit 1dc4d1e6 authored by Stefano Brivio's avatar Stefano Brivio Committed by David S. Miller
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rc80211-pid: add sharpening factor 



This patch introduces a PID sharpening factor for faster response after
association and low activity events.

Signed-off-by: default avatarStefano Brivio <stefano.brivio@polimi.it>
Signed-off-by: default avatarMattias Nissler <mattias.nissler@gmx.de>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 90d501d6

net/mac80211/rc80211_pid.c

+27 −8
Original line number Original line Diff line number Diff line
@@ -23,13 +23,16 @@ 
 *

 *

 * The controller basically computes the following:

 * 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

 * where

 * 	adj	adjustment value that is used to switch TX rate (see below)

 * 	adj	adjustment value that is used to switch TX rate (see below)

 * 	err	current error: target vs. current failed frames percentage

 * 	err	current error: target vs. current failed frames percentage

 * 	last_err	last error

 * 	last_err	last error

 * 	err_avg	average (i.e. poor man's integral) of recent errors

 * 	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

 * 	CP	Proportional coefficient

 * 	CI	Integral coefficient

 * 	CI	Integral coefficient

 * 	CD	Derivative coefficient

 * 	CD	Derivative coefficient
@@ -65,6 +68,10 @@ 
#define RC_PID_SMOOTHING_SHIFT 3

#define RC_PID_SMOOTHING_SHIFT 3

#define RC_PID_SMOOTHING (1 << RC_PID_SMOOTHING_SHIFT)

#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. */

/* Fixed point arithmetic shifting amount. */

#define RC_PID_ARITH_SHIFT 8

#define RC_PID_ARITH_SHIFT 8
@@ -131,8 +138,11 @@ struct rc_pid_sta_info { 
	 */

	 */

	s32 err_avg_sc;

	s32 err_avg_sc;





	/* Last framed failes percentage sample */

	/* Last framed failes percentage sample. */

	u32 last_pf;

	u32 last_pf;



	/* Sharpening needed. */

	u8 sharp_cnt;

};

};





/* Algorithm parameters. We keep them on a per-algorithm approach, so they can

/* Algorithm parameters. We keep them on a per-algorithm approach, so they can
@@ -267,19 +277,25 @@ static void rate_control_pid_sample(struct rc_pid_info *pinfo, 




	mode = local->oper_hw_mode;

	mode = local->oper_hw_mode;

	spinfo = sta->rate_ctrl_priv;

	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;

	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. */

	 * still a good measurement and copy it. */

	if (spinfo->tx_num_xmit == 0)

	if (unlikely(spinfo->tx_num_xmit == 0))

		pf = spinfo->last_pf;

		pf = spinfo->last_pf;

	else {

	else {

		pf = spinfo->tx_num_failed * 100 / spinfo->tx_num_xmit;

		pf = spinfo->tx_num_failed * 100 / spinfo->tx_num_xmit;

		pf <<= RC_PID_ARITH_SHIFT;

		pf <<= RC_PID_ARITH_SHIFT;

	}





	spinfo->tx_num_xmit = 0;

	spinfo->tx_num_xmit = 0;

	spinfo->tx_num_failed = 0;

	spinfo->tx_num_failed = 0;

	}





	/* If we just switched rate, update the rate behaviour info. */

	/* If we just switched rate, update the rate behaviour info. */

	if (pinfo->oldrate != sta->txrate) {

	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;

	spinfo->err_avg_sc = spinfo->err_avg_sc - err_avg + err_prop;

	err_int = spinfo->err_avg_sc >> RC_PID_SMOOTHING_SHIFT;

	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;

	spinfo->last_pf = pf;

	if (spinfo->sharp_cnt)

			spinfo->sharp_cnt--;





	/* Compute the controller output. */

	/* Compute the controller output. */

	adj = (err_prop * pinfo->coeff_p + err_int * pinfo->coeff_i

	adj = (err_prop * pinfo->coeff_p + err_int * pinfo->coeff_i