From mboxrd@z Thu Jan  1 00:00:00 1970
From: mathieu.desnoyers@efficios.com (Mathieu Desnoyers)
Date: Tue, 15 Nov 2011 06:35:51 -0500
Subject: [ltt-dev] [PATCH 9/9] change strategy for AR_RANDOM
In-Reply-To: <1321246259-21223-10-git-send-email-laijs@cn.fujitsu.com>
References: <1321246259-21223-1-git-send-email-laijs@cn.fujitsu.com>
	<1321246259-21223-10-git-send-email-laijs@cn.fujitsu.com>
Message-ID: <20111115113551.GH16701@Krystal>

* Lai Jiangshan (laijs at cn.fujitsu.com) wrote:
> Signed-off-by: Lai Jiangshan <laijs at cn.fujitsu.com>
> ---
>  tests/test_urcu_hash.c |   34 ++++++++++++++++++++++++++++++++--
>  1 files changed, 32 insertions(+), 2 deletions(-)
> 
> diff --git a/tests/test_urcu_hash.c b/tests/test_urcu_hash.c
> index 964a4e1..f07f0d4 100644
> --- a/tests/test_urcu_hash.c
> +++ b/tests/test_urcu_hash.c
> @@ -540,6 +540,37 @@ void free_node_cb(struct rcu_head *head)
>  	free(node);
>  }
>  
> +static inline
> +int thr_writer_add(void)
> +{
> +	static __thread int addremove_thread;
> +	unsigned addremove_random;
> +
> +	if (add_only)
> +		return 1;
> +
> +	if (addremove == AR_ADD)
> +		return 1;
> +
> +	if (addremove == AR_REMOVE)
> +		return 0;
> +
> +	addremove_random = test_rand_get_bits(2);
> +	if (addremove_random < 2)
> +		return addremove_random;
> +
> +	while (caa_unlikely(!addremove_thread))
> +		addremove_thread = test_rand_get_bits(16) - (1UL << 15);
> +
> +	if (addremove_thread > 0) {
> +		addremove_thread--;
> +		return 1;
> +	} else {
> +		addremove_thread++;
> +		return 0;
> +	}

Can you explain what this part of the change does ? I am slightly
uncomfortable about a while () loop in there too that depends on random
results.

Thanks,

Mathieu

> +}
> +
>  void *thr_writer(void *_count)
>  {
>  	struct lfht_test_node *node;
> @@ -562,8 +593,7 @@ void *thr_writer(void *_count)
>  	cmm_smp_mb();
>  
>  	for (;;) {
> -		if ((addremove == AR_ADD || add_only)
> -				|| (addremove == AR_RANDOM && test_rand_get_bits(1))) {
> +		if (thr_writer_add()) {
>  			node = malloc(sizeof(struct lfht_test_node));
>  			lfht_test_node_init(node);
>  			rcu_read_lock();
> -- 
> 1.7.4.4
> 

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