neigh: Keep neighbour cache entries if number of them is small enough. (2724680b) · Commits · 戴 / test

Since we have removed NCE (Neighbour Cache Entry) reference from routing entries, the only refcnt holders of an NCE are its timer (if running) and its owner table, in usual cases. As a result, neigh_periodic_work() purges NCEs over and over again even for gateways. It does not make sense to purge entries, if number of them is very small, so keep them. The minimum number of entries to keep is specified by gc_thresh1. Signed-off-by:

YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org> Signed-off-by:

David S. Miller <davem@davemloft.net>

Documentation/networking/ip-sysctl.txt

+5 −0

Original line number	Diff line number	Diff line
		@@ -26,6 +26,11 @@ route/max_size - INTEGER
		Maximum number of routes allowed in the kernel. Increase
		this when using large numbers of interfaces and/or routes.

		neigh/default/gc_thresh1 - INTEGER
		Minimum number of entries to keep. Garbage collector will not
		purge entries if there are fewer than this number.
		Default: 256

		neigh/default/gc_thresh3 - INTEGER
		Maximum number of neighbor entries allowed. Increase this
		when using large numbers of interfaces and when communicating

net/core/neighbour.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -778,6 +778,9 @@ static void neigh_periodic_work(struct work_struct *work)
		nht = rcu_dereference_protected(tbl->nht,
		lockdep_is_held(&tbl->lock));

		if (atomic_read(&tbl->entries) < tbl->gc_thresh1)
		goto out;

		/*
		* periodically recompute ReachableTime from random function
		*/
		@@ -832,6 +835,7 @@ next_elt:
		nht = rcu_dereference_protected(tbl->nht,
		lockdep_is_held(&tbl->lock));
		}
		out:
		/* Cycle through all hash buckets every base_reachable_time/2 ticks.
		* ARP entry timeouts range from 1/2 base_reachable_time to 3/2
		* base_reachable_time.

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