Re: [PATCH rcu 12/12] refscale: Add srcu_read_lock_lite() support using "srcu-lite"

[Frederic Weisbecker]

Le Wed, Oct 09, 2024 at 11:07:19AM -0700, Paul E. McKenney a écrit :
> This commit creates a new srcu-lite option for the refscale.scale_type
> module parameter that selects srcu_read_lock_lite() and
> srcu_read_unlock_lite().
> 
> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
> Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
> Cc: Andrii Nakryiko <andrii@xxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Kent Overstreet <kent.overstreet@xxxxxxxxx>
> Cc: <bpf@xxxxxxxxxxxxxxx>

This one does not apply cleanly. I assume there is some dependency to another
branch?

Thanks.

> ---
>  kernel/rcu/refscale.c | 51 +++++++++++++++++++++++++++++++++----------
>  1 file changed, 40 insertions(+), 11 deletions(-)
> 
> diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c
> index be66e5a67ee19..897d5b5494949 100644
> --- a/kernel/rcu/refscale.c
> +++ b/kernel/rcu/refscale.c
> @@ -216,6 +216,36 @@ static const struct ref_scale_ops srcu_ops = {
>  	.name		= "srcu"
>  };
>  
> +static void srcu_lite_ref_scale_read_section(const int nloops)
> +{
> +	int i;
> +	int idx;
> +
> +	for (i = nloops; i >= 0; i--) {
> +		idx = srcu_read_lock_lite(srcu_ctlp);
> +		srcu_read_unlock_lite(srcu_ctlp, idx);
> +	}
> +}
> +
> +static void srcu_lite_ref_scale_delay_section(const int nloops, const int udl, const int ndl)
> +{
> +	int i;
> +	int idx;
> +
> +	for (i = nloops; i >= 0; i--) {
> +		idx = srcu_read_lock_lite(srcu_ctlp);
> +		un_delay(udl, ndl);
> +		srcu_read_unlock_lite(srcu_ctlp, idx);
> +	}
> +}
> +
> +static const struct ref_scale_ops srcu_lite_ops = {
> +	.init		= rcu_sync_scale_init,
> +	.readsection	= srcu_lite_ref_scale_read_section,
> +	.delaysection	= srcu_lite_ref_scale_delay_section,
> +	.name		= "srcu-lite"
> +};
> +
>  #ifdef CONFIG_TASKS_RCU
>  
>  // Definitions for RCU Tasks ref scale testing: Empty read markers.
> @@ -1133,27 +1163,26 @@ ref_scale_init(void)
>  	long i;
>  	int firsterr = 0;
>  	static const struct ref_scale_ops *scale_ops[] = {
> -		&rcu_ops, &srcu_ops, RCU_TRACE_OPS RCU_TASKS_OPS &refcnt_ops, &rwlock_ops,
> -		&rwsem_ops, &lock_ops, &lock_irq_ops, &acqrel_ops, &sched_clock_ops, &clock_ops,
> -		&jiffies_ops, &typesafe_ref_ops, &typesafe_lock_ops, &typesafe_seqlock_ops,
> +		&rcu_ops, &srcu_ops, &srcu_lite_ops, RCU_TRACE_OPS RCU_TASKS_OPS
> +		&refcnt_ops, &rwlock_ops, &rwsem_ops, &lock_ops, &lock_irq_ops, &acqrel_ops,
> +		&sched_clock_ops, &clock_ops, &jiffies_ops, &typesafe_ref_ops, &typesafe_lock_ops,
> +		&typesafe_seqlock_ops,
>  	};
>  
>  	if (!torture_init_begin(scale_type, verbose))
>  		return -EBUSY;
>  
>  	for (i = 0; i < ARRAY_SIZE(scale_ops); i++) {
> -		cur_ops = scale_ops[i];
> -		if (strcmp(scale_type, cur_ops->name) == 0)
> +		cur_ops = scale_ops[i]; if (strcmp(scale_type,
> +		cur_ops->name) == 0)
>  			break;
>  	}
>  	if (i == ARRAY_SIZE(scale_ops)) {
> -		pr_alert("rcu-scale: invalid scale type: \"%s\"\n", scale_type);
> -		pr_alert("rcu-scale types:");
> -		for (i = 0; i < ARRAY_SIZE(scale_ops); i++)
> +		pr_alert("rcu-scale: invalid scale type: \"%s\"\n",
> +		scale_type); pr_alert("rcu-scale types:"); for (i = 0;
> +		i < ARRAY_SIZE(scale_ops); i++)
>  			pr_cont(" %s", scale_ops[i]->name);
> -		pr_cont("\n");
> -		firsterr = -EINVAL;
> -		cur_ops = NULL;
> +		pr_cont("\n"); firsterr = -EINVAL; cur_ops = NULL;
>  		goto unwind;
>  	}
>  	if (cur_ops->init)
> -- 
> 2.40.1
>