Messages in this thread Patch in this message |  | | From | Zqiang <> | Subject | [PATCH v2] rcu: Make defer_qs_iw as hard irq-work under RT kernel with strict grace period configuration | Date | Mon, 4 Apr 2022 07:59:32 +0800 |
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When the CONFIG_RCU_STRICT_GRACE_PERIOD is enabled, on non-PREEMPT_RT kernel, the init_irq_work() make the defer_qs_iw irq-work execute in interrupt context. however, on PREEMPT_RT kernel, the init_irq_work() make defer_qs_iq irq-work execute in rt-fifo irq_work kthreads. when system booting, there are a lot of defer_qs_iw irq-work to be processed in rt-fifo irq_work kthreads, it occupies boot CPU for long time and cause other kthread cannot get the boot CPU, the boot process occurs hang. use IRQ_WORK_INIT_HARD() to initialize defer_qs_iw irq-work, can ensure the defer_qs_iw irq-work execute in interrupt context, under PREEMPT_RT kernel with the CONFIG_RCU_STRICT_GRACE_PERIOD is enabled.
Signed-off-by: Zqiang <qiang1.zhang@intel.com> --- v1->v2: Use IRQ_WORK_INIT_HARD initialize defer_qs_iw only under RT kernel with CONFIG_RCU_STRICT_GRACE_PERIOD is enabled.
kernel/rcu/tree_plugin.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 3037c2536e1f..e6196a23793c 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -661,7 +661,13 @@ static void rcu_read_unlock_special(struct task_struct *t) expboost && !rdp->defer_qs_iw_pending && cpu_online(rdp->cpu)) { // Get scheduler to re-evaluate and call hooks. // If !IRQ_WORK, FQS scan will eventually IPI. - init_irq_work(&rdp->defer_qs_iw, rcu_preempt_deferred_qs_handler); + if (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD) && + IS_ENABLED(CONFIG_PREEMPT_RT)) + rdp->defer_qs_iw = IRQ_WORK_INIT_HARD( + rcu_preempt_deferred_qs_handler); + else + init_irq_work(&rdp->defer_qs_iw, + rcu_preempt_deferred_qs_handler); rdp->defer_qs_iw_pending = true; irq_work_queue_on(&rdp->defer_qs_iw, rdp->cpu); } -- 2.25.1
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