htb: reorder struct htb_class fields for performance

[~andy/linux] / net / sched / sch_htb.c

diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index adaedd79389ccd0775a824c9e3c61aef2ea5355e..7954e73d118ac6857a33ab1a49da4160acdae3f4 100644 (file)
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -65,6 +65,10 @@ static int htb_hysteresis __read_mostly = 0; /* whether to use mode hysteresis f
 module_param    (htb_hysteresis, int, 0640);
 MODULE_PARM_DESC(htb_hysteresis, "Hysteresis mode, less CPU load, less accurate");
 
+static int htb_rate_est = 0; /* htb classes have a default rate estimator */
+module_param(htb_rate_est, int, 0640);
+MODULE_PARM_DESC(htb_rate_est, "setup a default rate estimator (4sec 16sec) for htb classes");
+
 /* used internaly to keep status of single class */
 enum htb_cmode {
        HTB_CANT_SEND,          /* class can't send and can't borrow */
@@ -72,23 +76,39 @@ enum htb_cmode {
        HTB_CAN_SEND            /* class can send */
 };
 
-/* interior & leaf nodes; props specific to leaves are marked L: */
+/* interior & leaf nodes; props specific to leaves are marked L:
+ * To reduce false sharing, place mostly read fields at beginning,
+ * and mostly written ones at the end.
+ */
 struct htb_class {
        struct Qdisc_class_common common;
-       /* general class parameters */
-       struct gnet_stats_basic_packed bstats;
-       struct gnet_stats_queue qstats;
-       struct gnet_stats_rate_est rate_est;
-       struct tc_htb_xstats xstats;    /* our special stats */
-       int refcnt;             /* usage count of this class */
+       struct psched_ratecfg   rate;
+       struct psched_ratecfg   ceil;
+       s64                     buffer, cbuffer;/* token bucket depth/rate */
+       s64                     mbuffer;        /* max wait time */
+       int                     prio;           /* these two are used only by leaves... */
+       int                     quantum;        /* but stored for parent-to-leaf return */
+
+       struct tcf_proto        *filter_list;   /* class attached filters */
+       int                     filter_cnt;
+       int                     refcnt;         /* usage count of this class */
 
-       /* topology */
-       int level;              /* our level (see above) */
-       unsigned int children;
-       struct htb_class *parent;       /* parent class */
+       int                     level;          /* our level (see above) */
+       unsigned int            children;
+       struct htb_class        *parent;        /* parent class */
+
+       struct gnet_stats_rate_est64 rate_est;
+
+       /*
+        * Written often fields
+        */
+       struct gnet_stats_basic_packed bstats;
+       struct gnet_stats_queue qstats;
+       struct tc_htb_xstats    xstats; /* our special stats */
 
-       int prio;               /* these two are used only by leaves... */
-       int quantum;            /* but stored for parent-to-leaf return */
+       /* token bucket parameters */
+       s64                     tokens, ctokens;/* current number of tokens */
+       s64                     t_c;            /* checkpoint time */
 
        union {
                struct htb_class_leaf {
@@ -107,24 +127,12 @@ struct htb_class {
                        u32 last_ptr_id[TC_HTB_NUMPRIO];
                } inner;
        } un;
-       struct rb_node node[TC_HTB_NUMPRIO];    /* node for self or feed tree */
-       struct rb_node pq_node; /* node for event queue */
-       s64     pq_key;
-
-       int prio_activity;      /* for which prios are we active */
-       enum htb_cmode cmode;   /* current mode of the class */
-
-       /* class attached filters */
-       struct tcf_proto *filter_list;
-       int filter_cnt;
+       s64                     pq_key;
 
-       /* token bucket parameters */
-       struct psched_ratecfg rate;
-       struct psched_ratecfg ceil;
-       s64     buffer, cbuffer;        /* token bucket depth/rate */
-       s64     mbuffer;                /* max wait time */
-       s64     tokens, ctokens;        /* current number of tokens */
-       s64     t_c;                    /* checkpoint time */
+       int                     prio_activity;  /* for which prios are we active */
+       enum htb_cmode          cmode;          /* current mode of the class */
+       struct rb_node          pq_node;        /* node for event queue */
+       struct rb_node          node[TC_HTB_NUMPRIO];   /* node for self or feed tree */
 };
 
 struct htb_sched {
@@ -1366,12 +1374,14 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
                if (!cl)
                        goto failure;
 
-               err = gen_new_estimator(&cl->bstats, &cl->rate_est,
-                                       qdisc_root_sleeping_lock(sch),
-                                       tca[TCA_RATE] ? : &est.nla);
-               if (err) {
-                       kfree(cl);
-                       goto failure;
+               if (htb_rate_est || tca[TCA_RATE]) {
+                       err = gen_new_estimator(&cl->bstats, &cl->rate_est,
+                                               qdisc_root_sleeping_lock(sch),
+                                               tca[TCA_RATE] ? : &est.nla);
+                       if (err) {
+                               kfree(cl);
+                               goto failure;
+                       }
                }
 
                cl->refcnt = 1;