ip: speedup ip link

ip link has quadratic behavior because store_nlmsg()
has a head list pointer and search the end of list.

Provides a head/tail to cut time.

Time with 128000 net devices, to do "ip link show dev xxx"

Before: 2m3.594s
After: 0m2.830s

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

diff --git a/ip/ipaddress.c b/ip/ipaddress.c
index 9ab65ec78e2224290024ec1ef2a6c4cd67890d20..1db7fd02f6be2037798f75fed2d2c6795ff90fa4 100644 (file)
--- a/ip/ipaddress.c
+++ b/ip/ipaddress.c
@@ -717,6 +717,12 @@ struct nlmsg_list
        struct nlmsghdr   h;
 };
 
+struct nlmsg_chain
+{
+       struct nlmsg_list *head;
+       struct nlmsg_list *tail;
+};
+
 static int print_selected_addrinfo(int ifindex, struct nlmsg_list *ainfo, FILE *fp)
 {
        for ( ;ainfo ;  ainfo = ainfo->next) {
@@ -742,9 +748,8 @@ static int print_selected_addrinfo(int ifindex, struct nlmsg_list *ainfo, FILE *
 static int store_nlmsg(const struct sockaddr_nl *who, struct nlmsghdr *n,
                       void *arg)
 {
-       struct nlmsg_list **linfo = (struct nlmsg_list**)arg;
+       struct nlmsg_chain *lchain = (struct nlmsg_chain *)arg;
        struct nlmsg_list *h;
-       struct nlmsg_list **lp;
 
        h = malloc(n->nlmsg_len+sizeof(void*));
        if (h == NULL)
@@ -753,8 +758,11 @@ static int store_nlmsg(const struct sockaddr_nl *who, struct nlmsghdr *n,
        memcpy(&h->h, n, n->nlmsg_len);
        h->next = NULL;
 
-       for (lp = linfo; *lp; lp = &(*lp)->next) /* NOTHING */;
-       *lp = h;
+       if (lchain->tail)
+               lchain->tail->next = h;
+       else
+               lchain->head = h;
+       lchain->tail = h;
 
        ll_remember_index(who, n, NULL);
        return 0;
@@ -762,8 +770,8 @@ static int store_nlmsg(const struct sockaddr_nl *who, struct nlmsghdr *n,
 
 static int ipaddr_list_or_flush(int argc, char **argv, int flush)
 {
-       struct nlmsg_list *linfo = NULL;
-       struct nlmsg_list *ainfo = NULL;
+       struct nlmsg_chain linfo = { NULL, NULL};
+       struct nlmsg_chain ainfo = { NULL, NULL};
        struct nlmsg_list *l, *n;
        char *filter_dev = NULL;
        int no_link = 0;
@@ -953,7 +961,7 @@ flush_done:
 
        if (filter.family && filter.family != AF_PACKET) {
                struct nlmsg_list **lp;
-               lp=&linfo;
+               lp = &linfo.head;
 
                if (filter.oneline)
                        no_link = 1;
@@ -963,7 +971,7 @@ flush_done:
                        struct ifinfomsg *ifi = NLMSG_DATA(&l->h);
                        struct nlmsg_list *a;
 
-                       for (a=ainfo; a; a=a->next) {
+                       for (a = ainfo.head; a; a = a->next) {
                                struct nlmsghdr *n = &a->h;
                                struct ifaddrmsg *ifa = NLMSG_DATA(n);
 
@@ -1010,12 +1018,12 @@ flush_done:
                }
        }
 
-       for (l=linfo; l; l = n) {
+       for (l = linfo.head; l; l = n) {
                n = l->next;
                if (no_link || print_linkinfo(NULL, &l->h, stdout) == 0) {
                        struct ifinfomsg *ifi = NLMSG_DATA(&l->h);
                        if (filter.family != AF_PACKET)
-                               print_selected_addrinfo(ifi->ifi_index, ainfo, stdout);
+                               print_selected_addrinfo(ifi->ifi_index, ainfo.head, stdout);
                }
                fflush(stdout);
                free(l);