From: Peter Zijlstra <peterz@infradead.org>
To: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Linux PM <linux-pm@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Zhang Rui <rui.zhang@intel.com>,
Rafael Wysocki <rafael.j.wysocki@intel.com>,
"Chen, Yu C" <yu.c.chen@intel.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Petr Mladek <pmladek@suse.com>,
Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
Arjan van de Ven <arjan@linux.intel.com>
Subject: Re: [PATCH 1/3] idle: add support for tasks that inject idle
Date: Mon, 14 Nov 2016 15:57:21 +0100 [thread overview]
Message-ID: <20161114145721.GE3142@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1478718312-12847-2-git-send-email-jacob.jun.pan@linux.intel.com>
On Wed, Nov 09, 2016 at 11:05:10AM -0800, Jacob Pan wrote:
> static inline bool is_idle_task(const struct task_struct *p)
> {
> - return p->pid == 0;
> + return !!(p->flags & PF_IDLE);
> }
> +void play_idle()
> +{
> + /*
> + * Only FIFO tasks can disable the tick since they don't need the forced
> + * preemption.
> + */
> + WARN_ON_ONCE(current->policy != SCHED_FIFO);
> + WARN_ON_ONCE(current->nr_cpus_allowed != 1);
> + WARN_ON_ONCE(!(current->flags & PF_KTHREAD));
> + WARN_ON_ONCE(!(current->flags & PF_NO_SETAFFINITY));
> + rcu_sleep_check();
> +
> + preempt_disable();
> + current->flags |= PF_IDLE;
> + do_idle();
> + current->flags &= ~PF_IDLE;
Whoops, that will clear PF_IDLE from the idle thread. Maybe do something
like:
unsigned int idle_flag = (~current->flags & PF_IDLE)
current->flags |= PF_IDLE;
current->flags ^= idle_flag;
> +
> + preempt_fold_need_resched();
> + preempt_enable();
> +}
> +EXPORT_SYMBOL_GPL(play_idle);
> @@ -299,5 +313,7 @@ void cpu_startup_entry(enum cpuhp_state state)
> #endif
> arch_cpu_idle_prepare();
> cpuhp_online_idle(state);
> - cpu_idle_loop();
> + while (1)
> + do_idle();
> +
> }
next prev parent reply other threads:[~2016-11-14 14:57 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-09 19:05 [PATCH 0/3] Stop sched tick in idle injection task Jacob Pan
2016-11-09 19:05 ` [PATCH 1/3] idle: add support for tasks that inject idle Jacob Pan
2016-11-14 14:57 ` Peter Zijlstra [this message]
2016-11-14 15:01 ` Peter Zijlstra
2016-11-14 15:01 ` Peter Zijlstra
2016-11-14 16:20 ` Jacob Pan
2016-11-14 16:22 ` Peter Zijlstra
2016-11-14 16:29 ` Jacob Pan
2016-11-09 19:05 ` [PATCH 2/3] cpuidle: allow setting deepest idle Jacob Pan
2016-11-14 14:58 ` Peter Zijlstra
2016-11-09 19:05 ` [PATCH 3/3] thermal/powerclamp: use PF_IDLE in injection kthread Jacob Pan
2016-11-14 15:11 ` Peter Zijlstra
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