[IPV4] FIB_HASH : Avoid unecessary loop in fn_hash_dump_zone()
I noticed "ip route list" was slower than "cat /proc/net/route" on a
machine with a full Internet routing table (214392 entries : Special
thanks to Robert ;) )
This is similar to problem reported in commit
d8c9283089287341c85a0a69de32c2287a990e71 ("[IPV4] ROUTE: ip_rt_dump()
is unecessary slow")
Fix is to avoid scanning the begining of fz_hash table, but directly
seek to the right offset.
Before patch :
time ip route >/tmp/ROUTE
real 0m1.285s
user 0m0.712s
sys 0m0.436s
After patch
# time ip route >/tmp/ROUTE
real 0m0.835s
user 0m0.692s
sys 0m0.124s
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/fib_hash.c b/net/ipv4/fib_hash.c
index 99071d7..0dfee27 100644
--- a/net/ipv4/fib_hash.c
+++ b/net/ipv4/fib_hash.c
@@ -721,19 +721,18 @@
{
int h, s_h;
+ if (fz->fz_hash == NULL)
+ return skb->len;
s_h = cb->args[3];
- for (h=0; h < fz->fz_divisor; h++) {
- if (h < s_h) continue;
- if (h > s_h)
- memset(&cb->args[4], 0,
- sizeof(cb->args) - 4*sizeof(cb->args[0]));
- if (fz->fz_hash == NULL ||
- hlist_empty(&fz->fz_hash[h]))
+ for (h = s_h; h < fz->fz_divisor; h++) {
+ if (hlist_empty(&fz->fz_hash[h]))
continue;
- if (fn_hash_dump_bucket(skb, cb, tb, fz, &fz->fz_hash[h])<0) {
+ if (fn_hash_dump_bucket(skb, cb, tb, fz, &fz->fz_hash[h]) < 0) {
cb->args[3] = h;
return -1;
}
+ memset(&cb->args[4], 0,
+ sizeof(cb->args) - 4*sizeof(cb->args[0]));
}
cb->args[3] = h;
return skb->len;
@@ -749,14 +748,13 @@
read_lock(&fib_hash_lock);
for (fz = table->fn_zone_list, m=0; fz; fz = fz->fz_next, m++) {
if (m < s_m) continue;
- if (m > s_m)
- memset(&cb->args[3], 0,
- sizeof(cb->args) - 3*sizeof(cb->args[0]));
if (fn_hash_dump_zone(skb, cb, tb, fz) < 0) {
cb->args[2] = m;
read_unlock(&fib_hash_lock);
return -1;
}
+ memset(&cb->args[3], 0,
+ sizeof(cb->args) - 3*sizeof(cb->args[0]));
}
read_unlock(&fib_hash_lock);
cb->args[2] = m;