From: "Paul E. McKenney" <paulmck@kernel.org>
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
rostedt@goodmis.org, Zqiang <qiang1.zhang@intel.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
"Paul E . McKenney" <paulmck@kernel.org>
Subject: [PATCH rcu 04/10] rcu: Create per-cpu rcuc kthreads only when rcutree.use_softirq=0
Date: Fri, 4 Feb 2022 15:24:00 -0800 [thread overview]
Message-ID: <20220204232406.814-4-paulmck@kernel.org> (raw)
In-Reply-To: <20220204232355.GA728@paulmck-ThinkPad-P17-Gen-1>
From: Zqiang <qiang1.zhang@intel.com>
The per-CPU "rcuc" kthreads are used only by kernels booted with
rcutree.use_softirq=0, but they are nevertheless unconditionally created
by kernels built with CONFIG_RCU_BOOST=y. This results in "rcuc"
kthreads being created that are never actually used. This commit
therefore refrains from creating these kthreads unless the kernel
is actually booted with rcutree.use_softirq=0.
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/tree.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index a4c25a6283b0b..4e5e37e5ee3c9 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2894,7 +2894,7 @@ static int __init rcu_spawn_core_kthreads(void)
for_each_possible_cpu(cpu)
per_cpu(rcu_data.rcu_cpu_has_work, cpu) = 0;
- if (!IS_ENABLED(CONFIG_RCU_BOOST) && use_softirq)
+ if (use_softirq)
return 0;
WARN_ONCE(smpboot_register_percpu_thread(&rcu_cpu_thread_spec),
"%s: Could not start rcuc kthread, OOM is now expected behavior\n", __func__);
--
2.31.1.189.g2e36527f23
next prev parent reply other threads:[~2022-02-04 23:24 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-04 23:23 [PATCH rcu 0/10] Real-time-related updates for v5.18 Paul E. McKenney
2022-02-04 23:23 ` [PATCH rcu 01/10] rcu: Mark accesses to boost_starttime Paul E. McKenney
2022-02-04 23:23 ` [PATCH rcu 02/10] rcu/nocb: Handle concurrent nocb kthreads creation Paul E. McKenney
2022-02-04 23:23 ` [PATCH rcu 03/10] rcu: Remove unused rcu_state.boost Paul E. McKenney
2022-02-04 23:24 ` Paul E. McKenney [this message]
2022-02-04 23:24 ` [PATCH rcu 05/10] rcu: Move kthread_prio bounds-check to a separate function Paul E. McKenney
2022-02-04 23:24 ` [PATCH rcu 06/10] rcu: Make priority of grace-period thread consistent Paul E. McKenney
2022-02-04 23:24 ` [PATCH rcu 07/10] rcu: Elevate priority of offloaded callback threads Paul E. McKenney
2022-02-04 23:24 ` [PATCH rcu 08/10] rcu: Update documentation regarding kthread_prio cmdline parameter Paul E. McKenney
2022-02-04 23:24 ` [PATCH rcu 09/10] rcu: Don't deboost before reporting expedited quiescent state Paul E. McKenney
2022-02-04 23:24 ` [PATCH rcu 10/10] rcu: Add per-CPU rcuc task dumps to RCU CPU stall warnings Paul E. McKenney
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