rhashtable: Add comment on choice of elasticity value (27ed44a5) · Commits · 戴 / test

This patch adds a comment on the choice of the value 16 as the maximum chain length before we force a rehash. Signed-off-by:

lib/rhashtable.c

+12 −0

Original line number	Diff line number	Diff line
		@@ -736,6 +736,18 @@ int rhashtable_init(struct rhashtable *ht,

		ht->p.min_size = max(ht->p.min_size, HASH_MIN_SIZE);

		/* The maximum (not average) chain length grows with the
		* size of the hash table, at a rate of (log N)/(log log N).
		* The value of 16 is selected so that even if the hash
		* table grew to 2^32 you would not expect the maximum
		* chain length to exceed it unless we are under attack
		* (or extremely unlucky).
		*
		* As this limit is only to detect attacks, we don't need
		* to set it to a lower value as you'd need the chain
		* length to vastly exceed 16 to have any real effect
		* on the system.
		*/
		if (!params->insecure_elasticity)
		ht->elasticity = 16;