net_sched: red: split red_parms into parms and vars

This patch splits the red_parms structure into two components.

One holding the RED 'constant' parameters, and one containing the
variables.

This permits a size reduction of GRED qdisc, and is a preliminary step
to add an optional RED unit to SFQ.

SFQRED will have a single red_parms structure shared by all flows, and a
private red_vars per flow.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Dave Taht <dave.taht@gmail.com>
CC: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 55 insertions, 43 deletions

diff --git a/include/net/red.h b/include/net/red.h
index ef715a16cce4..baab385a4736 100644
--- a/include/net/red.h
+++ b/include/net/red.h
@@ -137,7 +137,9 @@ struct red_parms {
         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 */
@@ -152,6 +154,16 @@ 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,
@@ -160,13 +172,6 @@ static inline void red_set_parms(struct red_parms *p,
         int delta = qth_max - qth_min;
         u32 max_p_delta;
 
-        /* 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;
-
-        p->qcount       = -1;
         p->qth_min      = qth_min << Wlog;
         p->qth_max      = qth_max << Wlog;
         p->Wlog         = Wlog;
@@ -197,31 +202,32 @@ static inline void red_set_parms(struct red_parms *p,
         memcpy(p->Stab, stab, sizeof(p->Stab));
 }
 
-static inline int red_is_idling(const 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(const 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;
 
@@ -248,7 +254,7 @@ static inline unsigned long red_calc_qavg_from_idle_time(const struct red_parms
         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:
                  *
@@ -257,16 +263,17 @@ static inline unsigned long red_calc_qavg_from_idle_time(const struct red_parms
                  * 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(const struct red_parms *p,
+                                                       const struct red_vars *v,
                                                        unsigned int backlog)
 {
         /*
@@ -278,16 +285,17 @@ static inline unsigned long red_calc_qavg_no_idle_time(const struct red_parms *p
          *
          * --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(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);
 }
 
 
@@ -296,7 +304,9 @@ 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, 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.
 
@@ -314,7 +324,7 @@ static inline int red_mark_probability(const struct red_parms *p, unsigned long
 
            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 {
@@ -323,7 +333,7 @@ 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;
@@ -339,27 +349,29 @@ enum {
         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;
         }
 
@@ -367,14 +379,14 @@ static inline int red_action(struct red_parms *p, unsigned long qavg)
         return RED_DONT_MARK;
 }
 
-static inline void red_adaptative_algo(struct red_parms *p)
+static inline void red_adaptative_algo(struct red_parms *p, struct red_vars *v)
 {
         unsigned long qavg;
         u32 max_p_delta;
 
-        qavg = p->qavg;
-        if (red_is_idling(p))
-                qavg = red_calc_qavg_from_idle_time(p);
+        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;