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[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
d8c9283089 ("[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>
This commit is contained in:
Eric Dumazet 2008-01-18 04:30:21 -08:00 committed by David S. Miller
parent 49d85c502e
commit 8d3f099abe
1 changed files with 9 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
net/ipv4/fib_hash.c
View File

@ -721,19 +721,18 @@ fn_hash_dump_zone(struct sk_buff *skb, struct netlink_callback *cb,
{
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 @@ static int fn_hash_dump(struct fib_table *tb, struct sk_buff *skb, struct netlin
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;