linux-kernel - Re: [PATCH v3 1/3] rcutorture: Allow a negative value for nfakewriters

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Message-ID: <Z78lNRKjLQKigyLw@pc636>
Date: Wed, 26 Feb 2025 15:29:09 +0100
From: Uladzislau Rezki <urezki@...il.com>
To: Joel Fernandes <joelagnelf@...dia.com>
Cc: "Uladzislau Rezki (Sony)" <urezki@...il.com>,
	"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 v3 1/3] rcutorture: Allow a negative value for
 nfakewriters

On Tue, Feb 25, 2025 at 04:24:09PM -0500, Joel Fernandes wrote:
> On Tue, Feb 25, 2025 at 12:00:18PM +0100, Uladzislau Rezki (Sony) wrote:
> > 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_online_cpus() during torture initialization.
> > 
> > Reviewed-by: Paul E. McKenney <paulmck@...nel.org>
> > Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
> > ---
> >  kernel/rcu/rcutorture.c | 22 ++++++++++++++++------
> >  1 file changed, 16 insertions(+), 6 deletions(-)
> > 
> > diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
> > index d98b3bd6d91f..f376262532ce 100644
> > --- a/kernel/rcu/rcutorture.c
> > +++ b/kernel/rcu/rcutorture.c
> > @@ -148,6 +148,7 @@ MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, srcu, ...)");
> 
> IMO, this should also be updated to reflect the possibily to set it negative
> and hence to number CPUs:
> 
> torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
> 
You can set it to a negative as well as to number of CPUs or any other
number.

--
Uladzislau Rezki