linux-kernel - Re: [RFC][PATCHv2 8/8] printk: enable printk offloading

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Date:   Tue, 4 Apr 2017 22:20:50 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>, Jan Kara <jack@...e.cz>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Eric Biederman <ebiederm@...ssion.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, Pavel Machek <pavel@....cz>,
        Len Brown <len.brown@...el.com>, linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Subject: Re: [RFC][PATCHv2 8/8] printk: enable printk offloading

On (04/03/17 17:42), Petr Mladek wrote:
> > +/*
> > + * Init printk kthread at late_initcall stage, after core/arch/device/etc.
> > + * initialization.
> > + */
> > +static int __init init_printk_kthread(void)
> > +{
> > +	struct task_struct *thread;
> > +
> > +	thread = kthread_run(printk_kthread_func, NULL, "printk");
> > +	if (IS_ERR(thread)) {
> > +		pr_err("printk: unable to create printing thread\n");
> > +		return PTR_ERR(thread);
> > +	}
> > +
> > +	printk_kthread = thread;
> > +	return 0;
> > +}
> > +late_initcall(init_printk_kthread);
> 
> I like the simplicity. I just wonder if people on tiny devices might
> want to disable it. In each case, it does not make sense on non-SMP
> machines or when people force the emergency mode all the time.
> 
> I am not sure what is the practice here. I wonder if we should be
> proactive or keep it as is and wait until anyone complains. IMHO,
> it is not that big deal but...

I tend to agree that this is not a big deal, as of now.
I've bigger concerns.

	-ss