net_sched: sfq: allow divisor to be a parameter

SFQ currently uses a 1024 slots hash table, and its internal structure
(sfq_sched_data) allocation needs order-1 page on x86_64

Allow tc command to specify a divisor value (hash table size), between 1
and 65536.
If no value is provided, assume the 1024 default size.

This allows admins to setup smaller (or bigger) SFQ for specific needs.

This also brings back sfq_sched_data allocations to order-0 ones, saving
3KB per SFQ qdisc.

Jesper uses ~55.000 SFQ in one machine, this patch should free 165 MB of
memory.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Patrick McHardy <kaber@trash.net>
CC: Jesper Dangaard Brouer <hawk@diku.dk>
CC: Jarek Poplawski <jarkao2@gmail.com>
CC: Jamal Hadi Salim <hadi@cyberus.ca>
CC: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 30 insertions, 12 deletions

diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c
index 54a36f43a1f1..156ad30980b5 100644
--- a/net/sched/sch_sfq.c
+++ b/net/sched/sch_sfq.c
@@ -21,6 +21,7 @@
 #include <linux/skbuff.h>
 #include <linux/jhash.h>
 #include <linux/slab.h>
+#include <linux/vmalloc.h>
 #include <net/ip.h>
 #include <net/netlink.h>
 #include <net/pkt_sched.h>
@@ -76,7 +77,8 @@
 #define SFQ_DEPTH               128 /* max number of packets per flow */
 #define SFQ_SLOTS               128 /* max number of flows */
 #define SFQ_EMPTY_SLOT          255
-#define SFQ_HASH_DIVISOR        1024
+#define SFQ_DEFAULT_HASH_DIVISOR 1024
+
 /* We use 16 bits to store allot, and want to handle packets up to 64K
  * Scale allot by 8 (1<<3) so that no overflow occurs.
  */
@@ -112,7 +114,7 @@ struct sfq_sched_data {
         int             perturb_period;
         unsigned int    quantum;        /* Allotment per round: MUST BE >= MTU */
         int             limit;
-
+        unsigned int    divisor;        /* number of slots in hash table */
 /* Variables */
         struct tcf_proto *filter_list;
         struct timer_list perturb_timer;
@@ -120,7 +122,7 @@ struct sfq_sched_data {
         sfq_index       cur_depth;      /* depth of longest slot */
         unsigned short  scaled_quantum; /* SFQ_ALLOT_SIZE(quantum) */
         struct sfq_slot *tail;          /* current slot in round */
-        sfq_index       ht[SFQ_HASH_DIVISOR];   /* Hash table */
+        sfq_index       *ht;            /* Hash table (divisor slots) */
         struct sfq_slot slots[SFQ_SLOTS];
         struct sfq_head dep[SFQ_DEPTH]; /* Linked list of slots, indexed by depth */
 };
@@ -137,7 +139,7 @@ static inline struct sfq_head *sfq_dep_head(struct sfq_sched_data *q, sfq_index
 
 static unsigned int sfq_fold_hash(struct sfq_sched_data *q, u32 h, u32 h1)
 {
-        return jhash_2words(h, h1, q->perturbation) & (SFQ_HASH_DIVISOR - 1);
+        return jhash_2words(h, h1, q->perturbation) & (q->divisor - 1);
 }
 
 static unsigned int sfq_hash(struct sfq_sched_data *q, struct sk_buff *skb)
@@ -201,7 +203,7 @@ static unsigned int sfq_classify(struct sk_buff *skb, struct Qdisc *sch,
 
         if (TC_H_MAJ(skb->priority) == sch->handle &&
             TC_H_MIN(skb->priority) > 0 &&
-            TC_H_MIN(skb->priority) <= SFQ_HASH_DIVISOR)
+            TC_H_MIN(skb->priority) <= q->divisor)
                 return TC_H_MIN(skb->priority);
 
         if (!q->filter_list)
@@ -219,7 +221,7 @@ static unsigned int sfq_classify(struct sk_buff *skb, struct Qdisc *sch,
                         return 0;
                 }
 #endif
-                if (TC_H_MIN(res.classid) <= SFQ_HASH_DIVISOR)
+                if (TC_H_MIN(res.classid) <= q->divisor)
                         return TC_H_MIN(res.classid);
         }
         return 0;
@@ -496,7 +498,11 @@ static int sfq_change(struct Qdisc *sch, struct nlattr *opt)
         q->perturb_period = ctl->perturb_period * HZ;
         if (ctl->limit)
                 q->limit = min_t(u32, ctl->limit, SFQ_DEPTH - 1);
-
+        if (ctl->divisor) {
+                if (!is_power_of_2(ctl->divisor) || ctl->divisor > 65536)
+                        return -EINVAL;
+                q->divisor = ctl->divisor;
+        }
         qlen = sch->q.qlen;
         while (sch->q.qlen > q->limit)
                 sfq_drop(sch);
@@ -514,15 +520,13 @@ static int sfq_change(struct Qdisc *sch, struct nlattr *opt)
 static int sfq_init(struct Qdisc *sch, struct nlattr *opt)
 {
         struct sfq_sched_data *q = qdisc_priv(sch);
+        size_t sz;
         int i;
 
         q->perturb_timer.function = sfq_perturbation;
         q->perturb_timer.data = (unsigned long)sch;
         init_timer_deferrable(&q->perturb_timer);
 
-        for (i = 0; i < SFQ_HASH_DIVISOR; i++)
-                q->ht[i] = SFQ_EMPTY_SLOT;
-
         for (i = 0; i < SFQ_DEPTH; i++) {
                 q->dep[i].next = i + SFQ_SLOTS;
                 q->dep[i].prev = i + SFQ_SLOTS;
@@ -531,6 +535,7 @@ static int sfq_init(struct Qdisc *sch, struct nlattr *opt)
         q->limit = SFQ_DEPTH - 1;
         q->cur_depth = 0;
         q->tail = NULL;
+        q->divisor = SFQ_DEFAULT_HASH_DIVISOR;
         if (opt == NULL) {
                 q->quantum = psched_mtu(qdisc_dev(sch));
                 q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum);
@@ -542,6 +547,15 @@ static int sfq_init(struct Qdisc *sch, struct nlattr *opt)
                         return err;
         }
 
+        sz = sizeof(q->ht[0]) * q->divisor;
+        q->ht = kmalloc(sz, GFP_KERNEL);
+        if (!q->ht && sz > PAGE_SIZE)
+                q->ht = vmalloc(sz);
+        if (!q->ht)
+                return -ENOMEM;
+        for (i = 0; i < q->divisor; i++)
+                q->ht[i] = SFQ_EMPTY_SLOT;
+
         for (i = 0; i < SFQ_SLOTS; i++) {
                 slot_queue_init(&q->slots[i]);
                 sfq_link(q, i);
@@ -556,6 +570,10 @@ static void sfq_destroy(struct Qdisc *sch)
         tcf_destroy_chain(&q->filter_list);
         q->perturb_period = 0;
         del_timer_sync(&q->perturb_timer);
+        if (is_vmalloc_addr(q->ht))
+                vfree(q->ht);
+        else
+                kfree(q->ht);
 }
 
 static int sfq_dump(struct Qdisc *sch, struct sk_buff *skb)
@@ -568,7 +586,7 @@ static int sfq_dump(struct Qdisc *sch, struct sk_buff *skb)
         opt.perturb_period = q->perturb_period / HZ;
 
         opt.limit = q->limit;
-        opt.divisor = SFQ_HASH_DIVISOR;
+        opt.divisor = q->divisor;
         opt.flows = q->limit;
 
         NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
@@ -646,7 +664,7 @@ static void sfq_walk(struct Qdisc *sch, struct qdisc_walker *arg)
         if (arg->stop)
                 return;
 
-        for (i = 0; i < SFQ_HASH_DIVISOR; i++) {
+        for (i = 0; i < q->divisor; i++) {
                 if (q->ht[i] == SFQ_EMPTY_SLOT ||
                     arg->count < arg->skip) {
                         arg->count++;