linux-kernel - Re: [PATCH 1/4] rcutorture: Allow a negative value for nfakewriters

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Message-ID: <Z5lEN8WdvPyq7dRs@pc636>
Date: Tue, 28 Jan 2025 21:55:19 +0100
From: Uladzislau Rezki <urezki@...il.com>
To: "Paul E . McKenney" <paulmck@...nel.org>
Cc: "Paul E . McKenney" <paulmck@...nel.org>,
	Boqun Feng <boqun.feng@...il.com>, RCU <rcu@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <frederic@...nel.org>,
	Cheung Wall <zzqq0103.hey@...il.com>,
	Neeraj upadhyay <Neeraj.Upadhyay@....com>,
	Joel Fernandes <joel@...lfernandes.org>,
	Oleksiy Avramchenko <oleksiy.avramchenko@...y.com>
Subject: Re: [PATCH 1/4] rcutorture: Allow a negative value for nfakewriters

Hello, Paul!

> Currently "nfakewriters" parameter can be set to any value but
> there is no possibility to adjust it automatically based on how
> many CPUs a system has where a test is run on.
> 
> To address this, if the "nfakewriters" is set to negative it will
> be adjusted to num_possible_cpus() during torture initialization.
> 
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
> ---
>  kernel/rcu/rcutorture.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
> index d26fb1d33ed9..6bc161e1e8ac 100644
> --- a/kernel/rcu/rcutorture.c
> +++ b/kernel/rcu/rcutorture.c
> @@ -4050,6 +4050,10 @@ rcu_torture_init(void)
>  					  writer_task);
>  	if (torture_init_error(firsterr))
>  		goto unwind;
> +
> +	if (nfakewriters < 0)
> +		nfakewriters = (int) num_possible_cpus();
> +
>  	if (nfakewriters > 0) {
>  		fakewriter_tasks = kcalloc(nfakewriters,
>  					   sizeof(fakewriter_tasks[0]),
> -- 
> 2.39.5
> 

Don't you mind to take this as well? It is needed for:

rcu: Update TREE05.boot to test normal synchronize_rcu()

--
Uladzislau Rezki