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Diffstat (limited to 'ANDROID_3.4.5/include/net/red.h')
| -rw-r--r-- | ANDROID_3.4.5/include/net/red.h | 405 |
1 files changed, 0 insertions, 405 deletions
diff --git a/ANDROID_3.4.5/include/net/red.h b/ANDROID_3.4.5/include/net/red.h deleted file mode 100644 index ef46058d..00000000 --- a/ANDROID_3.4.5/include/net/red.h +++ /dev/null @@ -1,405 +0,0 @@ -#ifndef __NET_SCHED_RED_H -#define __NET_SCHED_RED_H - -#include <linux/types.h> -#include <linux/bug.h> -#include <net/pkt_sched.h> -#include <net/inet_ecn.h> -#include <net/dsfield.h> -#include <linux/reciprocal_div.h> - -/* Random Early Detection (RED) algorithm. - ======================================= - - Source: Sally Floyd and Van Jacobson, "Random Early Detection Gateways - for Congestion Avoidance", 1993, IEEE/ACM Transactions on Networking. - - This file codes a "divisionless" version of RED algorithm - as written down in Fig.17 of the paper. - - Short description. - ------------------ - - When a new packet arrives we calculate the average queue length: - - avg = (1-W)*avg + W*current_queue_len, - - W is the filter time constant (chosen as 2^(-Wlog)), it controls - the inertia of the algorithm. To allow larger bursts, W should be - decreased. - - if (avg > th_max) -> packet marked (dropped). - if (avg < th_min) -> packet passes. - if (th_min < avg < th_max) we calculate probability: - - Pb = max_P * (avg - th_min)/(th_max-th_min) - - and mark (drop) packet with this probability. - Pb changes from 0 (at avg==th_min) to max_P (avg==th_max). - max_P should be small (not 1), usually 0.01..0.02 is good value. - - max_P is chosen as a number, so that max_P/(th_max-th_min) - is a negative power of two in order arithmetics to contain - only shifts. - - - Parameters, settable by user: - ----------------------------- - - qth_min - bytes (should be < qth_max/2) - qth_max - bytes (should be at least 2*qth_min and less limit) - Wlog - bits (<32) log(1/W). - Plog - bits (<32) - - Plog is related to max_P by formula: - - max_P = (qth_max-qth_min)/2^Plog; - - F.e. if qth_max=128K and qth_min=32K, then Plog=22 - corresponds to max_P=0.02 - - Scell_log - Stab - - Lookup table for log((1-W)^(t/t_ave). - - - NOTES: - - Upper bound on W. - ----------------- - - If you want to allow bursts of L packets of size S, - you should choose W: - - L + 1 - th_min/S < (1-(1-W)^L)/W - - th_min/S = 32 th_min/S = 4 - - log(W) L - -1 33 - -2 35 - -3 39 - -4 46 - -5 57 - -6 75 - -7 101 - -8 135 - -9 190 - etc. - */ - -/* - * Adaptative RED : An Algorithm for Increasing the Robustness of RED's AQM - * (Sally FLoyd, Ramakrishna Gummadi, and Scott Shenker) August 2001 - * - * Every 500 ms: - * if (avg > target and max_p <= 0.5) - * increase max_p : max_p += alpha; - * else if (avg < target and max_p >= 0.01) - * decrease max_p : max_p *= beta; - * - * target :[qth_min + 0.4*(qth_min - qth_max), - * qth_min + 0.6*(qth_min - qth_max)]. - * alpha : min(0.01, max_p / 4) - * beta : 0.9 - * max_P is a Q0.32 fixed point number (with 32 bits mantissa) - * max_P between 0.01 and 0.5 (1% - 50%) [ Its no longer a negative power of two ] - */ -#define RED_ONE_PERCENT ((u32)DIV_ROUND_CLOSEST(1ULL<<32, 100)) - -#define MAX_P_MIN (1 * RED_ONE_PERCENT) -#define MAX_P_MAX (50 * RED_ONE_PERCENT) -#define MAX_P_ALPHA(val) min(MAX_P_MIN, val / 4) - -#define RED_STAB_SIZE 256 -#define RED_STAB_MASK (RED_STAB_SIZE - 1) - -struct red_stats { - u32 prob_drop; /* Early probability drops */ - u32 prob_mark; /* Early probability marks */ - u32 forced_drop; /* Forced drops, qavg > max_thresh */ - u32 forced_mark; /* Forced marks, qavg > max_thresh */ - u32 pdrop; /* Drops due to queue limits */ - u32 other; /* Drops due to drop() calls */ -}; - -struct red_parms { - /* Parameters */ - u32 qth_min; /* Min avg length threshold: Wlog scaled */ - u32 qth_max; /* Max avg length threshold: Wlog scaled */ - u32 Scell_max; - u32 max_P; /* probability, [0 .. 1.0] 32 scaled */ - u32 max_P_reciprocal; /* reciprocal_value(max_P / qth_delta) */ - u32 qth_delta; /* max_th - min_th */ - u32 target_min; /* min_th + 0.4*(max_th - min_th) */ - u32 target_max; /* min_th + 0.6*(max_th - min_th) */ - u8 Scell_log; - u8 Wlog; /* log(W) */ - u8 Plog; /* random number bits */ - u8 Stab[RED_STAB_SIZE]; -}; - -struct red_vars { - /* Variables */ - int qcount; /* Number of packets since last random - number generation */ - u32 qR; /* Cached random number */ - - unsigned long qavg; /* Average queue length: Wlog scaled */ - ktime_t qidlestart; /* Start of current idle period */ -}; - -static inline u32 red_maxp(u8 Plog) -{ - return Plog < 32 ? (~0U >> Plog) : ~0U; -} - -static inline void red_set_vars(struct red_vars *v) -{ - /* Reset average queue length, the value is strictly bound - * to the parameters below, reseting hurts a bit but leaving - * it might result in an unreasonable qavg for a while. --TGR - */ - v->qavg = 0; - - v->qcount = -1; -} - -static inline void red_set_parms(struct red_parms *p, - u32 qth_min, u32 qth_max, u8 Wlog, u8 Plog, - u8 Scell_log, u8 *stab, u32 max_P) -{ - int delta = qth_max - qth_min; - u32 max_p_delta; - - p->qth_min = qth_min << Wlog; - p->qth_max = qth_max << Wlog; - p->Wlog = Wlog; - p->Plog = Plog; - if (delta < 0) - delta = 1; - p->qth_delta = delta; - if (!max_P) { - max_P = red_maxp(Plog); - max_P *= delta; /* max_P = (qth_max - qth_min)/2^Plog */ - } - p->max_P = max_P; - max_p_delta = max_P / delta; - max_p_delta = max(max_p_delta, 1U); - p->max_P_reciprocal = reciprocal_value(max_p_delta); - - /* RED Adaptative target : - * [min_th + 0.4*(min_th - max_th), - * min_th + 0.6*(min_th - max_th)]. - */ - delta /= 5; - p->target_min = qth_min + 2*delta; - p->target_max = qth_min + 3*delta; - - p->Scell_log = Scell_log; - p->Scell_max = (255 << Scell_log); - - if (stab) - memcpy(p->Stab, stab, sizeof(p->Stab)); -} - -static inline int red_is_idling(const struct red_vars *v) -{ - return v->qidlestart.tv64 != 0; -} - -static inline void red_start_of_idle_period(struct red_vars *v) -{ - v->qidlestart = ktime_get(); -} - -static inline void red_end_of_idle_period(struct red_vars *v) -{ - v->qidlestart.tv64 = 0; -} - -static inline void red_restart(struct red_vars *v) -{ - red_end_of_idle_period(v); - v->qavg = 0; - v->qcount = -1; -} - -static inline unsigned long red_calc_qavg_from_idle_time(const struct red_parms *p, - const struct red_vars *v) -{ - s64 delta = ktime_us_delta(ktime_get(), v->qidlestart); - long us_idle = min_t(s64, delta, p->Scell_max); - int shift; - - /* - * The problem: ideally, average length queue recalcultion should - * be done over constant clock intervals. This is too expensive, so - * that the calculation is driven by outgoing packets. - * When the queue is idle we have to model this clock by hand. - * - * SF+VJ proposed to "generate": - * - * m = idletime / (average_pkt_size / bandwidth) - * - * dummy packets as a burst after idle time, i.e. - * - * v->qavg *= (1-W)^m - * - * This is an apparently overcomplicated solution (f.e. we have to - * precompute a table to make this calculation in reasonable time) - * I believe that a simpler model may be used here, - * but it is field for experiments. - */ - - shift = p->Stab[(us_idle >> p->Scell_log) & RED_STAB_MASK]; - - if (shift) - return v->qavg >> shift; - else { - /* Approximate initial part of exponent with linear function: - * - * (1-W)^m ~= 1-mW + ... - * - * Seems, it is the best solution to - * problem of too coarse exponent tabulation. - */ - us_idle = (v->qavg * (u64)us_idle) >> p->Scell_log; - - if (us_idle < (v->qavg >> 1)) - return v->qavg - us_idle; - else - return v->qavg >> 1; - } -} - -static inline unsigned long red_calc_qavg_no_idle_time(const struct red_parms *p, - const struct red_vars *v, - unsigned int backlog) -{ - /* - * NOTE: v->qavg is fixed point number with point at Wlog. - * The formula below is equvalent to floating point - * version: - * - * qavg = qavg*(1-W) + backlog*W; - * - * --ANK (980924) - */ - return v->qavg + (backlog - (v->qavg >> p->Wlog)); -} - -static inline unsigned long red_calc_qavg(const struct red_parms *p, - const struct red_vars *v, - unsigned int backlog) -{ - if (!red_is_idling(v)) - return red_calc_qavg_no_idle_time(p, v, backlog); - else - return red_calc_qavg_from_idle_time(p, v); -} - - -static inline u32 red_random(const struct red_parms *p) -{ - return reciprocal_divide(net_random(), p->max_P_reciprocal); -} - -static inline int red_mark_probability(const struct red_parms *p, - const struct red_vars *v, - unsigned long qavg) -{ - /* The formula used below causes questions. - - OK. qR is random number in the interval - (0..1/max_P)*(qth_max-qth_min) - i.e. 0..(2^Plog). If we used floating point - arithmetics, it would be: (2^Plog)*rnd_num, - where rnd_num is less 1. - - Taking into account, that qavg have fixed - point at Wlog, two lines - below have the following floating point equivalent: - - max_P*(qavg - qth_min)/(qth_max-qth_min) < rnd/qcount - - Any questions? --ANK (980924) - */ - return !(((qavg - p->qth_min) >> p->Wlog) * v->qcount < v->qR); -} - -enum { - RED_BELOW_MIN_THRESH, - RED_BETWEEN_TRESH, - RED_ABOVE_MAX_TRESH, -}; - -static inline int red_cmp_thresh(const struct red_parms *p, unsigned long qavg) -{ - if (qavg < p->qth_min) - return RED_BELOW_MIN_THRESH; - else if (qavg >= p->qth_max) - return RED_ABOVE_MAX_TRESH; - else - return RED_BETWEEN_TRESH; -} - -enum { - RED_DONT_MARK, - RED_PROB_MARK, - RED_HARD_MARK, -}; - -static inline int red_action(const struct red_parms *p, - struct red_vars *v, - unsigned long qavg) -{ - switch (red_cmp_thresh(p, qavg)) { - case RED_BELOW_MIN_THRESH: - v->qcount = -1; - return RED_DONT_MARK; - - case RED_BETWEEN_TRESH: - if (++v->qcount) { - if (red_mark_probability(p, v, qavg)) { - v->qcount = 0; - v->qR = red_random(p); - return RED_PROB_MARK; - } - } else - v->qR = red_random(p); - - return RED_DONT_MARK; - - case RED_ABOVE_MAX_TRESH: - v->qcount = -1; - return RED_HARD_MARK; - } - - BUG(); - return RED_DONT_MARK; -} - -static inline void red_adaptative_algo(struct red_parms *p, struct red_vars *v) -{ - unsigned long qavg; - u32 max_p_delta; - - qavg = v->qavg; - if (red_is_idling(v)) - qavg = red_calc_qavg_from_idle_time(p, v); - - /* v->qavg is fixed point number with point at Wlog */ - qavg >>= p->Wlog; - - if (qavg > p->target_max && p->max_P <= MAX_P_MAX) - p->max_P += MAX_P_ALPHA(p->max_P); /* maxp = maxp + alpha */ - else if (qavg < p->target_min && p->max_P >= MAX_P_MIN) - p->max_P = (p->max_P/10)*9; /* maxp = maxp * Beta */ - - max_p_delta = DIV_ROUND_CLOSEST(p->max_P, p->qth_delta); - max_p_delta = max(max_p_delta, 1U); - p->max_P_reciprocal = reciprocal_value(max_p_delta); -} -#endif |