From 8d3f099abe25c21670cb5728178a1f286952782d Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 18 Jan 2008 04:30:21 -0800 Subject: [PATCH] [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 Signed-off-by: David S. Miller --- net/ipv4/fib_hash.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-) diff --git a/net/ipv4/fib_hash.c b/net/ipv4/fib_hash.c index 99071d79c5..0dfee27cfb 100644 --- a/net/ipv4/fib_hash.c +++ b/net/ipv4/fib_hash.c @@ -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; -- 2.39.5