netfilter: conntrack: adjust nf_conntrack_buckets default value

Manually bumping either nf_conntrack_buckets or nf_conntrack_max has
become a common task as our Linux servers tend to serve more and more
clients/applications, so let's adjust nf_conntrack_buckets this to a
more updated value.

Now for systems with more than 4GB of memory, nf_conntrack_buckets
becomes 65536 instead of 16384, resulting in nf_conntrack_max=256k
entries.

Signed-off-by: Marcelo Ricardo Leitner <mleitner@redhat.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 8 insertions, 3 deletions

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index a11674806707..da58cd4f2cb7 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1624,13 +1624,18 @@ int nf_conntrack_init_start(void)
 	for (i = 0; i < CONNTRACK_LOCKS; i++)
 		spin_lock_init(&nf_conntrack_locks[i]);
 
-	/* Idea from tcp.c: use 1/16384 of memory.  On i386: 32MB
-	 * machine has 512 buckets. >= 1GB machines have 16384 buckets. */
 	if (!nf_conntrack_htable_size) {
+		/* Idea from tcp.c: use 1/16384 of memory.
+		 * On i386: 32MB machine has 512 buckets.
+		 * >= 1GB machines have 16384 buckets.
+		 * >= 4GB machines have 65536 buckets.
+		 */
 		nf_conntrack_htable_size
 			= (((totalram_pages << PAGE_SHIFT) / 16384)
 			   / sizeof(struct hlist_head));
-		if (totalram_pages > (1024 * 1024 * 1024 / PAGE_SIZE))
+		if (totalram_pages > (4 * (1024 * 1024 * 1024 / PAGE_SIZE)))
+			nf_conntrack_htable_size = 65536;
+		else if (totalram_pages > (1024 * 1024 * 1024 / PAGE_SIZE))
 			nf_conntrack_htable_size = 16384;
 		if (nf_conntrack_htable_size < 32)
 			nf_conntrack_htable_size = 32;