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Date: Wed, 27 Aug 2014 11:34:12 +0100 From: Thomas Graf <tgraf@...g.ch> To: Ying Xue <ying.xue@...driver.com> Cc: davem@...emloft.net, eric.dumazet@...il.com, netdev@...r.kernel.org Subject: Re: [PATCH RFC] lib/rhashtable: allow users to set the minimum shifts of shrinking On 08/27/14 at 04:57pm, Ying Xue wrote: > diff --git a/lib/rhashtable.c b/lib/rhashtable.c > index a2c7881..1466e2d 100644 > --- a/lib/rhashtable.c > +++ b/lib/rhashtable.c > @@ -293,12 +293,15 @@ EXPORT_SYMBOL_GPL(rhashtable_expand); > int rhashtable_shrink(struct rhashtable *ht, gfp_t flags) > { > struct bucket_table *ntbl, *tbl = rht_dereference(ht->tbl, ht); > + size_t min_shift = ilog2(HASH_MIN_SIZE); > struct rhash_head __rcu **pprev; > unsigned int i; > > ASSERT_RHT_MUTEX(ht); > > - if (tbl->size <= HASH_MIN_SIZE) > + if (ht->p.min_shift) > + min_shift = max(ht->p.min_shift, min_shift); > + if (ht->shift <= min_shift) > return 0; I like it. Can you translate HASH_MIN_SIZE to .minshift in rhashtable_init()? That way we only have to deal with .min_shift in rhashtable_shrink(). Note that shrinking can also be disabled by not providing a .shrink_decision function in rhashtable_params if the shrinking is too expensive for your case. > -static size_t rounded_hashtable_size(unsigned int nelem) > +static size_t rounded_hashtable_size(struct rhashtable_params *params) > { > - return max(roundup_pow_of_two(nelem * 4 / 3), HASH_MIN_SIZE); > + size_t size = HASH_MIN_SIZE; > + > + if (params->min_shift) > + size = max((1UL << params->min_shift), HASH_MIN_SIZE); > + > + return max(roundup_pow_of_two(params->nelem_hint * 4 / 3), size); > } Same here. If you merge the provided .min_shift with HASH_MIN_SIZE in rhashtable_init() before calculating the size, the above logic can be simplified a lot. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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