netfilter: conntrack: resched gc again if eviction rate is high

If we evicted a large fraction of the scanned conntrack entries re-schedule
the next gc cycle for immediate execution.

This triggers during tests where load is high, then drops to zero and
many connections will be in TW/CLOSE state with < 30 second timeouts.

Without this change it will take several minutes until conntrack count
comes back to normal.

Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index f95a9e9..7c66ce4 100644 (file)
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -945,6 +945,7 @@ static void gc_worker(struct work_struct *work)
 {
        unsigned int i, goal, buckets = 0, expired_count = 0;
        unsigned long next_run = GC_INTERVAL;
+       unsigned int ratio, scanned = 0;
        struct conntrack_gc_work *gc_work;
 
        gc_work = container_of(work, struct conntrack_gc_work, dwork.work);
@@ -969,6 +970,7 @@ static void gc_worker(struct work_struct *work)
                hlist_nulls_for_each_entry_rcu(h, n, &ct_hash[i], hnnode) {
                        tmp = nf_ct_tuplehash_to_ctrack(h);
 
+                       scanned++;
                        if (nf_ct_is_expired(tmp)) {
                                nf_ct_gc_expired(tmp);
                                expired_count++;
@@ -988,6 +990,10 @@ static void gc_worker(struct work_struct *work)
        if (gc_work->exiting)
                return;
 
+       ratio = scanned ? expired_count * 100 / scanned : 0;
+       if (ratio >= 90)
+               next_run = 0;
+
        gc_work->last_bucket = i;
        schedule_delayed_work(&gc_work->dwork, next_run);
 }