ss: speedup resolve_service()

Lets implement a full cache with proper hash table, memory got cheaper
these days.

Before :

$ time ss -t | wc -l
529678

real	0m22.708s
user	0m19.591s
sys	0m2.969s

After :

$ time ss -t | wc -l
528291

real	0m5.078s
user	0m4.099s
sys	0m0.985s

Signed-off-by: Eric Dumazet <edumazet@google.com>

diff --git a/misc/ss.c b/misc/ss.c
index 9fe229fed718e0c7066ab02ead6af4390112db82..68bffe289ba9079c76113e7f05f90e66161a0c7f 100644 (file)
--- a/misc/ss.c
+++ b/misc/ss.c
@@ -858,8 +858,7 @@ static const char *print_ms_timer(int timeout)
        return buf;
 }
 
-struct scache
-{
+struct scache {
        struct scache *next;
        int port;
        char *name;
@@ -949,11 +948,15 @@ static const char *__resolve_service(int port)
        return NULL;
 }
 
+#define SCACHE_BUCKETS 1024
+static struct scache *cache_htab[SCACHE_BUCKETS];
 
 static const char *resolve_service(int port)
 {
        static char buf[128];
-       static struct scache cache[256];
+       struct scache *c;
+       const char *res;
+       int hash;
 
        if (port == 0) {
                buf[0] = '*';
@@ -961,45 +964,35 @@ static const char *resolve_service(int port)
                return buf;
        }
 
-       if (resolve_services) {
-               if (dg_proto == RAW_PROTO) {
-                       return inet_proto_n2a(port, buf, sizeof(buf));
-               } else {
-                       struct scache *c;
-                       const char *res;
-                       int hash = (port^(((unsigned long)dg_proto)>>2))&255;
-
-                       for (c = &cache[hash]; c; c = c->next) {
-                               if (c->port == port &&
-                                   c->proto == dg_proto) {
-                                       if (c->name)
-                                               return c->name;
-                                       goto do_numeric;
-                               }
-                       }
+       if (!resolve_services)
+               goto do_numeric;
 
-                       if ((res = __resolve_service(port)) != NULL) {
-                               if ((c = malloc(sizeof(*c))) == NULL)
-                                       goto do_numeric;
-                       } else {
-                               c = &cache[hash];
-                               if (c->name)
-                                       free(c->name);
-                       }
-                       c->port = port;
-                       c->name = NULL;
-                       c->proto = dg_proto;
-                       if (res) {
-                               c->name = strdup(res);
-                               c->next = cache[hash].next;
-                               cache[hash].next = c;
-                       }
-                       if (c->name)
-                               return c->name;
-               }
+       if (dg_proto == RAW_PROTO)
+               return inet_proto_n2a(port, buf, sizeof(buf));
+
+
+       hash = (port^(((unsigned long)dg_proto)>>2)) % SCACHE_BUCKETS;
+
+       for (c = cache_htab[hash]; c; c = c->next) {
+               if (c->port == port && c->proto == dg_proto)
+                       goto do_cache;
        }
 
-       do_numeric:
+       c = malloc(sizeof(*c));
+       if (!c)
+               goto do_numeric;
+       res = __resolve_service(port);
+       c->port = port;
+       c->name = res ? strdup(res) : NULL;
+       c->proto = dg_proto;
+       c->next = cache_htab[hash];
+       cache_htab[hash] = c;
+
+do_cache:
+       if (c->name)
+               return c->name;
+
+do_numeric:
        sprintf(buf, "%u", port);
        return buf;
 }