From mboxrd@z Thu Jan  1 00:00:00 1970
From: mathieu.desnoyers@efficios.com (Mathieu Desnoyers)
Date: Tue, 15 Nov 2011 06:31:08 -0500
Subject: [ltt-dev] [PATCH 8/9] add duplicated node test
In-Reply-To: <1321246259-21223-9-git-send-email-laijs@cn.fujitsu.com>
References: <1321246259-21223-1-git-send-email-laijs@cn.fujitsu.com>
	<1321246259-21223-9-git-send-email-laijs@cn.fujitsu.com>
Message-ID: <20111115113108.GG16701@Krystal>

* Lai Jiangshan (laijs at cn.fujitsu.com) wrote:
> Signed-off-by: Lai Jiangshan <laijs at cn.fujitsu.com>
> ---
>  tests/test_urcu_hash.c |   12 ++++++++++++
>  1 files changed, 12 insertions(+), 0 deletions(-)
> 
> diff --git a/tests/test_urcu_hash.c b/tests/test_urcu_hash.c
> index 3730c2b..964a4e1 100644
> --- a/tests/test_urcu_hash.c
> +++ b/tests/test_urcu_hash.c
> @@ -111,6 +111,7 @@ struct test_data {
>  struct lfht_test_node {
>  	struct cds_lfht_node node;
>  	unsigned long hash;
> +	unsigned long dup;
>  	unsigned long orig_hash;
>  	/* cache-cold for iteration */
>  	struct rcu_head head;
> @@ -406,6 +407,8 @@ void lfht_test_node_init(struct lfht_test_node *node)
>  			cds_lfht_next(test_ht, &iter);
>  		if (iter.node)
>  			hash = to_test_node(iter.node)->orig_hash;
> +
> +		node->dup = test_rand_get_bits(2);
>  	}
>  
>  	node->orig_hash = hash;
> @@ -427,6 +430,15 @@ void lfht_test_node_init(struct lfht_test_node *node)
>  static
>  int test_match(struct cds_lfht_node *node, void *key)
>  {
> +	struct lfht_test_node *u = to_test_node(node), *v = key;
> +
> +	if (caa_likely(u->hash != v->hash))
> +		return 0;
> +
> +	/* 56.25% (100% * 9 / 16) duplicated when hash value are the same */
> +	if (u->dup && u->dup == v->dup)
> +		return 1;

Oh, I see, so you use a flag in the node to specify if it is duplicated.
This is twisted ;)

Hrm, but cds_lfht_next_duplicate needs to follow next pointers to get
the duplicates, so I don't see how this approach works with the
rculfhash code.

It might be simpler to just create a physical duplicate and add it to
the table rather than this flag scheme. This would end up testing the
normal use of the table rather than a use-case nobody will use in
practice.

Thanks,

Mathieu

> +
>  	return 0;
>  }
>  
> -- 
> 1.7.4.4
> 

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com