Re: [PATCH tip/core/rcu 06/45] torture: Intensify locking test

[josh]

On Mon, Apr 28, 2014 at 05:24:54PM -0700, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
> 
> The current lock_torture_writer() spends too much time sleeping and not
> enough time hammering locks, as in an eight-CPU test will often only be
> utilizing a CPU or two.  This commit therefore makes lock_torture_writer()
> sleep less and hammer more.
> 
> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
> ---
>  kernel/locking/locktorture.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
> index f26b1a18e34e..b0d3e3c50672 100644
> --- a/kernel/locking/locktorture.c
> +++ b/kernel/locking/locktorture.c
> @@ -219,7 +219,8 @@ static int lock_torture_writer(void *arg)
>  	set_user_nice(current, 19);
>  
>  	do {
> -		schedule_timeout_uninterruptible(1);
> +		if ((torture_random(&rand) & 0xfffff) == 0)
> +			schedule_timeout_uninterruptible(1);

That's a one-in-1048576 chance of sleeping for a jiffy; is that frequent
enough to even bother sleeping at all?

>  		cur_ops->writelock();
>  		if (WARN_ON_ONCE(lock_is_write_held))
>  			lwsp->n_write_lock_fail++;
> -- 
> 1.8.1.5
> 
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