From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: Petr Mladek <pmladek@suse.com>
Cc: Jan Kara <jack@suse.cz>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Jan Kara <jack@suse.com>, Tejun Heo <tj@kernel.org>,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
linux-kernel@vger.kernel.org,
Byungchul Park <byungchul.park@lge.com>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Subject: Re: [RFC][PATCH v8 1/2] printk: Make printk() completely async
Date: Tue, 5 Apr 2016 02:01:05 +0900 [thread overview]
Message-ID: <20160404170105.GA573@swordfish> (raw)
In-Reply-To: <20160404094108.GI1023@pathway.suse.cz>
Hello,
On (04/04/16 11:41), Petr Mladek wrote:
[..]
> > So what about having printk_kthread_func() like:
> >
> > while (1) {
> > set_current_state(TASK_INTERRUPTIBLE);
> > if (!need_flush_console)
> > schedule();
> > __set_current_state(TASK_RUNNING);
> > need_flush_console = false;
> > console_lock();
> > console_unlock();
> > }
> >
> > In vprintk_emit() we do:
> >
> > if (!in_panic && printk_kthread) {
> > /* Offload printing to a schedulable context. */
> > need_flush_console = true;
> > wake_up_process(printk_kthread);
> > } else {
> > ...
> >
> > This guarantees that after message was appended to the buffer in
> > vprintk_emit(), the message got either printed by console_unlock() or
> > printk_kthread is in TASK_RUNNING state and will call console_unlock() once
> > scheduled. It also guarantees that printk_kthread_func() won't loop forever
> > when there's nothing to print. And that is all we need...
> >
> > I think the simplicity of this is worth the possible extra loops in
> > printk_kthread_func().
>
> I do not have strong opinion about this. I agree that the simplicity
> of your proposal is nice. You are much more experienced kernel
> developer. If you say that the potential extra loop is fine, I am
> fine with it as well :-)
>
works for me, re-sent.
the patch is even smaller now, and we almost have nothing else to
cut off from it :)
-ss
next prev parent reply other threads:[~2016-04-04 16:03 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-24 15:43 [RFC][PATCH v8 0/2] printk: Make printk() completely async Sergey Senozhatsky
2016-03-24 15:43 ` [RFC][PATCH v8 1/2] " Sergey Senozhatsky
2016-03-29 9:14 ` Jan Kara
2016-04-01 1:14 ` Sergey Senozhatsky
2016-03-31 11:12 ` Petr Mladek
2016-03-31 11:52 ` Jan Kara
2016-04-04 9:41 ` Petr Mladek
2016-04-04 17:01 ` Sergey Senozhatsky [this message]
2016-04-01 1:08 ` Sergey Senozhatsky
2016-04-01 8:59 ` Petr Mladek
2016-04-01 9:36 ` Sergey Senozhatsky
2016-04-01 11:30 ` Petr Mladek
2016-03-24 15:43 ` [RFC][PATCH v8 2/2] printk: Make wake_up_klogd_work_func() async Sergey Senozhatsky
2016-03-31 11:14 ` Petr Mladek
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