#include <net/pkt_sched.h>
#include <net/inet_ecn.h>
#include <net/dsfield.h>
+#include <linux/reciprocal_div.h>
/* Random Early Detection (RED) algorithm.
=======================================
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_parms {
/* Parameters */
- u32 qth_min; /* Min avg length threshold: A scaled */
- u32 qth_max; /* Max avg length threshold: A scaled */
+ u32 qth_min; /* Min avg length threshold: Wlog scaled */
+ u32 qth_max; /* Max avg length threshold: Wlog scaled */
u32 Scell_max;
- u32 Rmask; /* Cached random mask, see red_rmask */
+ 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: A scaled */
+ unsigned long qavg; /* Average queue length: Wlog scaled */
ktime_t qidlestart; /* Start of current idle period */
};
-static inline u32 red_rmask(u8 Plog)
+static inline u32 red_maxp(u8 Plog)
{
- return Plog < 32 ? ((1 << Plog) - 1) : ~0UL;
+ return Plog < 32 ? (~0U >> Plog) : ~0U;
}
-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)
+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
*/
- p->qavg = 0;
+ 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->qcount = -1;
p->qth_min = qth_min << Wlog;
p->qth_max = qth_max << Wlog;
p->Wlog = Wlog;
p->Plog = Plog;
- p->Rmask = red_rmask(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);
- memcpy(p->Stab, stab, sizeof(p->Stab));
+ if (stab)
+ memcpy(p->Stab, stab, sizeof(p->Stab));
}
-static inline int red_is_idling(struct red_parms *p)
+static inline int red_is_idling(const struct red_vars *v)
{
- return p->qidlestart.tv64 != 0;
+ return v->qidlestart.tv64 != 0;
}
-static inline void red_start_of_idle_period(struct red_parms *p)
+static inline void red_start_of_idle_period(struct red_vars *v)
{
- p->qidlestart = ktime_get();
+ v->qidlestart = ktime_get();
}
-static inline void red_end_of_idle_period(struct red_parms *p)
+static inline void red_end_of_idle_period(struct red_vars *v)
{
- p->qidlestart.tv64 = 0;
+ v->qidlestart.tv64 = 0;
}
-static inline void red_restart(struct red_parms *p)
+static inline void red_restart(struct red_vars *v)
{
- red_end_of_idle_period(p);
- p->qavg = 0;
- p->qcount = -1;
+ red_end_of_idle_period(v);
+ v->qavg = 0;
+ v->qcount = -1;
}
-static inline unsigned long red_calc_qavg_from_idle_time(struct red_parms *p)
+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(), p->qidlestart);
+ s64 delta = ktime_us_delta(ktime_get(), v->qidlestart);
long us_idle = min_t(s64, delta, p->Scell_max);
int shift;
shift = p->Stab[(us_idle >> p->Scell_log) & RED_STAB_MASK];
if (shift)
- return p->qavg >> shift;
+ return v->qavg >> shift;
else {
/* Approximate initial part of exponent with linear function:
*
* Seems, it is the best solution to
* problem of too coarse exponent tabulation.
*/
- us_idle = (p->qavg * (u64)us_idle) >> p->Scell_log;
+ us_idle = (v->qavg * (u64)us_idle) >> p->Scell_log;
- if (us_idle < (p->qavg >> 1))
- return p->qavg - us_idle;
+ if (us_idle < (v->qavg >> 1))
+ return v->qavg - us_idle;
else
- return p->qavg >> 1;
+ return v->qavg >> 1;
}
}
-static inline unsigned long red_calc_qavg_no_idle_time(struct red_parms *p,
+static inline unsigned long red_calc_qavg_no_idle_time(const struct red_parms *p,
+ const struct red_vars *v,
unsigned int backlog)
{
/*
*
* --ANK (980924)
*/
- return p->qavg + (backlog - (p->qavg >> p->Wlog));
+ return v->qavg + (backlog - (v->qavg >> p->Wlog));
}
-static inline unsigned long red_calc_qavg(struct red_parms *p,
+static inline unsigned long red_calc_qavg(const struct red_parms *p,
+ const struct red_vars *v,
unsigned int backlog)
{
- if (!red_is_idling(p))
- return red_calc_qavg_no_idle_time(p, 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);
+ return red_calc_qavg_from_idle_time(p, v);
}
-static inline u32 red_random(struct red_parms *p)
+
+static inline u32 red_random(const struct red_parms *p)
{
- return net_random() & p->Rmask;
+ return reciprocal_divide(net_random(), p->max_P_reciprocal);
}
-static inline int red_mark_probability(struct red_parms *p, unsigned long qavg)
+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..Rmask
+ 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, and Plog is related to max_P by
- max_P = (qth_max-qth_min)/2^Plog; two lines
+ 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) * p->qcount < p->qR);
+ return !(((qavg - p->qth_min) >> p->Wlog) * v->qcount < v->qR);
}
enum {
RED_ABOVE_MAX_TRESH,
};
-static inline int red_cmp_thresh(struct red_parms *p, unsigned long qavg)
+static inline int red_cmp_thresh(const struct red_parms *p, unsigned long qavg)
{
if (qavg < p->qth_min)
return RED_BELOW_MIN_THRESH;
RED_HARD_MARK,
};
-static inline int red_action(struct red_parms *p, unsigned long qavg)
+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:
- p->qcount = -1;
+ v->qcount = -1;
return RED_DONT_MARK;
case RED_BETWEEN_TRESH:
- if (++p->qcount) {
- if (red_mark_probability(p, qavg)) {
- p->qcount = 0;
- p->qR = red_random(p);
+ if (++v->qcount) {
+ if (red_mark_probability(p, v, qavg)) {
+ v->qcount = 0;
+ v->qR = red_random(p);
return RED_PROB_MARK;
}
} else
- p->qR = red_random(p);
+ v->qR = red_random(p);
return RED_DONT_MARK;
case RED_ABOVE_MAX_TRESH:
- p->qcount = -1;
+ v->qcount = -1;
return RED_HARD_MARK;
}
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);
+
+ /* p->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
projects / firefly-linux-kernel-4.4.55.git / blobdiff