From: Oleg Nesterov <oleg@redhat.com>
To: Cheng Chao <cs.os.kernel@gmail.com>
Cc: mingo@kernel.org, peterz@infradead.org, tj@kernel.org,
akpm@linux-foundation.org, chris@chris-wilson.co.uk,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] stop_machine: Make migration_cpu_stop() does useful works for CONFIG_PREEMPT_NONE
Date: Mon, 12 Sep 2016 13:03:07 +0200 [thread overview]
Message-ID: <20160912110307.GA2417@redhat.com> (raw)
In-Reply-To: <1473497532-5440-1-git-send-email-cs.os.kernel@gmail.com>
On 09/10, Cheng Chao wrote:
>
> @@ -126,6 +126,17 @@ int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
> cpu_stop_init_done(&done, 1);
> if (!cpu_stop_queue_work(cpu, &work))
> return -ENOENT;
> +
> +#if defined(CONFIG_PREEMPT_NONE)
> + /*
> + * Makes the stopper thread run as soon as possible.
> + * And if the caller is TASK_RUNNING, keeps the caller TASK_RUNNING.
> + * It's special useful for some callers which are expected to be
> + * TASK_ON_RQ_QUEUED.
> + * sched_exec does benefit from this improvement.
> + */
> + schedule();
> +#endif
> wait_for_completion(&done.completion);
> return done.ret;
> }
Cheng, I already tried twice to suggest to conditionalize this schedule,
because it can only help if cpu == smp_processor_id, and you didn't reply.
I still think _cond_resched() makes more sense.
I won't really argue if you prefer it this way. But did you see my emails?
Oleg.
next prev parent reply other threads:[~2016-09-12 11:03 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <OF73BCE1E4.D2224FEC-ON48258025.0022CFA7-48258025.0022E3DC@kedacom.com>
2016-09-09 8:13 ` [PATCH v2] stop_machine: Make migration_cpu_stop() does useful works for CONFIG_PREEMPT_NONE Cheng Chao
2016-09-09 8:19 ` chengchao
2016-09-09 13:14 ` Oleg Nesterov
2016-09-09 16:24 ` Peter Zijlstra
2016-09-10 8:52 ` [PATCH v3] " Cheng Chao
2016-09-10 9:51 ` Cheng Chao
2016-09-10 16:33 ` Peter Zijlstra
2016-09-12 11:03 ` Oleg Nesterov [this message]
2016-09-13 2:45 ` Cheng Chao
2016-09-12 11:37 ` Peter Zijlstra
2016-09-12 11:41 ` Peter Zijlstra
2016-09-12 13:05 ` Oleg Nesterov
2016-09-12 15:01 ` Peter Zijlstra
2016-09-13 16:14 ` Oleg Nesterov
2016-09-13 16:37 ` Peter Zijlstra
2016-09-14 2:07 ` Cheng Chao
2016-09-14 7:50 ` Peter Zijlstra
2016-09-14 15:45 ` Oleg Nesterov
2016-09-22 13:59 ` [tip:sched/core] sched/core: Optimize __schedule() tip-bot for Peter Zijlstra
2016-09-13 4:03 ` [PATCH v3] stop_machine: Make migration_cpu_stop() does useful works for CONFIG_PREEMPT_NONE Cheng Chao
2016-09-13 8:45 ` Peter Zijlstra
2016-09-14 2:01 ` [PATCH v4] stop_machine: Avoid a sleep and wakeup in the stop_one_cpu() Cheng Chao
2016-09-14 15:53 ` Oleg Nesterov
2016-09-18 2:07 ` Cheng Chao
2016-09-22 13:59 ` [tip:sched/core] stop_machine: Avoid a sleep and wakeup in stop_one_cpu() tip-bot for Cheng Chao
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