From:   "Zhang, Qiang1" <qiang1.zhang@intel.com>
To:     "Zhang, Qiang1" <qiang1.zhang@intel.com>,
        "paulmck@kernel.org" <paulmck@kernel.org>,
        "frederic@kernel.org" <frederic@kernel.org>,
        "quic_neeraju@quicinc.com" <quic_neeraju@quicinc.com>,
        "joel@joelfernandes.org" <joel@joelfernandes.org>
CC:     "rcu@vger.kernel.org" <rcu@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v3] rcutorture: Create nocb tasks only for
 CONFIG_RCU_NOCB_CPU=y kernels
Thread-Topic: [PATCH v3] rcutorture: Create nocb tasks only for
 CONFIG_RCU_NOCB_CPU=y kernels
Thread-Index: AQHZN2/UL1txlbJjvEezXlvE3XxcLK68xM7g
Date:   Fri, 3 Feb 2023 06:38:07 +0000
Message-ID: <PH0PR11MB5880EE5E5653216772BF1047DAD79@PH0PR11MB5880.namprd11.prod.outlook.com>
References: <20230203014021.3408798-1-qiang1.zhang@intel.com>
In-Reply-To: <20230203014021.3408798-1-qiang1.zhang@intel.com>
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>When setting nocbs_nthreads to start rcutorture test with a non-zero value=
,
>the nocb tasks will be created and invoke rcu_nocb_cpu_offload/deoffload()
>to toggle CPU's callback-offload state, but for CONFIG_RCU_NOCB_CPU=3Dn
>kernel, the rcu_nocb_cpu_offload/deoffload() is a no-op and this is also
>meaningless for torture_type is non-rcu.
>
>This commit therefore add member can_nocbs_toggle to rcu_torture_ops
>structure to avoid unnecessary nocb tasks creation.

Will change commit log next version.

Thanks
Zqiang

>
>Signed-off-by: Zqiang <qiang1.zhang@intel.com>
>---
> kernel/rcu/rcutorture.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
>diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
>index 297da28ce92d..d01127e0e8cd 100644
>--- a/kernel/rcu/rcutorture.c
>+++ b/kernel/rcu/rcutorture.c
>@@ -3708,6 +3708,12 @@ rcu_torture_init(void)
> 		pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabl=
ed.\n");
> 		fqs_duration =3D 0;
> 	}
>+	if (nocbs_nthreads !=3D 0 && (cur_ops !=3D &rcu_ops ||
>+					!IS_ENABLED(CONFIG_RCU_NOCB_CPU))) {
>+		pr_alert("rcu-torture types: %s and CONFIG_RCU_NOCB_CPU=3D%d, nocb togg=
le disabled.\n",
>+				cur_ops->name, IS_ENABLED(CONFIG_RCU_NOCB_CPU));
>+		nocbs_nthreads =3D 0;
>+	}
> 	if (cur_ops->init)
> 		cur_ops->init();
>=20
>--=20
>2.25.1