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Commit 2724680b authored by YOSHIFUJI Hideaki / 吉藤英明's avatar YOSHIFUJI Hideaki / 吉藤英明 Committed by David S. Miller
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neigh: Keep neighbour cache entries if number of them is small enough. 



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: default avatarYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 360eb5da

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.