Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread

From	Steven Rostedt <rostedt@goodmis.org>
Newsgroups	linux.kernel
Subject	Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread
Date	2017-06-30 15:40 +0200
Message-ID	<tY4jo-64M-27@gated-at.bofh.it> (permalink)
References	(4 earlier) <tN6eS-1Kf-31@gated-at.bofh.it> <tXk6S-6H0-7@gated-at.bofh.it> <tXCds-4I6-23@gated-at.bofh.it> <tY2KC-50c-15@gated-at.bofh.it> <tY3wZ-5xi-3@gated-at.bofh.it>
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On Fri, 30 Jun 2017 21:42:24 +0900
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> wrote:

> I apply a very simple litmus test. if the answer to the question
> "so we leave console_unlock() and there are pending messages,
> who and when is going to flush the remaining messages?" is
> "something sometime in the future" then it's a no-no.

I totally agree with this, but...

> 
> "something sometime in the future" is equal to "no one".
> 
> we must stay and continue printing. because it gives the right
> answer - "current process and right now. until someone else
> (+printk_kthread) takes over".

Would it be acceptable to have a user knob that allows for it not to
happen? That is, let the user of the kernel decide if they care about
critical prints or not? If a knob says, "only print X, then offload"
would that be allowed. Of course the default would be "only print ALL
OF IT" to keep the current behavior.

A lot of times the console isn't recorded to debug hard lock ups. I
know most desktops running a GUI do not. When ever my workstation locks
up, and it has no serial, I don't get to see the dmesg at all. In this
situation, I don't care if the prints are offloaded or not.

-- Steve

Thread

Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread Petr Mladek <pmladek@suse.com> - 2017-06-28 14:20 +0200
  Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread Andreas Mohr <andi@lisas.de> - 2017-06-29 08:30 +0200
    Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread Andreas Mohr <andi@lisas.de> - 2017-06-29 09:10 +0200
  Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-06-29 09:40 +0200
    Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2017-06-29 13:40 +0200
    Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-06-30 09:10 +0200
      Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2017-06-30 12:30 +0200
        Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-06-30 14:00 +0200
          Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2017-06-30 14:50 +0200
            Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-06-30 15:00 +0200
      Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread Petr Mladek <pmladek@suse.com> - 2017-06-30 15:20 +0200
        Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-06-30 15:40 +0200
          Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-07-03 13:20 +0200
        Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-06-30 16:20 +0200
    Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread Petr Mladek <pmladek@suse.com> - 2017-06-30 14:00 +0200
      Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-06-30 14:50 +0200
        Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread Steven Rostedt <rostedt@goodmis.org> - 2017-06-30 15:40 +0200
          Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-06-30 16:30 +0200
            Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread Steven Rostedt <rostedt@goodmis.org> - 2017-06-30 16:50 +0200
              Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-07-01 04:00 +0200

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