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[95.203.6.24]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-548514f9dc3sm516092e87.215.2025.02.26.10.16.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Feb 2025 10:16:26 -0800 (PST) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Wed, 26 Feb 2025 19:16:24 +0100 To: "Paul E. McKenney" Cc: Joel Fernandes , Uladzislau Rezki , Boqun Feng , RCU , LKML , Frederic Weisbecker , Cheung Wall , Neeraj upadhyay , Joel Fernandes , Oleksiy Avramchenko Subject: Re: [PATCH v3 1/3] rcutorture: Allow a negative value for nfakewriters Message-ID: References: <20250225110020.59221-1-urezki@gmail.com> <20250225212409.GA1807836@joelnvbox> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Feb 26, 2025 at 10:04:35AM -0800, Paul E. McKenney wrote: > On Wed, Feb 26, 2025 at 12:49:41PM -0500, Joel Fernandes wrote: > > > > > > On 2/26/2025 9:29 AM, Uladzislau Rezki wrote: > > > 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 > > >>> Signed-off-by: Uladzislau Rezki (Sony) > > >>> --- > > >>> 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. > > Sorry I just meant amend the description to something like "Number of RCU fake > > writer threads (or set to -1 for NR_CPUs)", so user does not have to read code > > to know that (and update the kernel cmdline params document as well). > > Should we also adjust the string for nreaders? > Makes sense. Both options are adjusted in same way. -- Uladzislau Rezki