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From: John Ogness <john.ogness@linutronix.de>
To: Petr Mladek <pmladek@suse.com>
Cc: Nigel Croxon <ncroxon@redhat.com>,
	"Theodore Y. Ts'o" <tytso@mit.edu>,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	dm-devel@redhat.com, Mikulas Patocka <mpatocka@redhat.com>,
	linux-serial@vger.kernel.org
Subject: Re: Serial console is causing system lock-up
Date: Tue, 12 Mar 2019 16:19:28 +0100	[thread overview]
Message-ID: <87zhq0yvb3.fsf@linutronix.de> (raw)
In-Reply-To: <20190312120824.4eaa4eyjcxvuzm23@pathway.suse.cz> (Petr Mladek's message of "Tue, 12 Mar 2019 13:08:24 +0100")

On 2019-03-12, Petr Mladek <pmladek@suse.com> wrote:
> On Tue 2019-03-12 09:17:49, John Ogness wrote:
>> The current printk implementation is handling all console printing as
>> best effort. Trying hard enough to dramatically affect the system,
>> but not trying hard enough to guarantee success.
>
> I agree that direct output is more reliable. It might be very useful
> for debugging some types of problems. The question is if it is worth
> the cost (code complexity, serializing CPUs == slowing down the
> entire system).
>
> But it is is possible that a reasonable offloading (in the direction
> of last Sergey's approach) might be a better deal.
>
>
> I suggest the following way forward (separate patchsets):
>
>     1. Replace log buffer (least controversial thing)
>     2. Reliable offload to kthread (would be useful anyway)
>     3. Atomic consoles (a lot of tricky code, might not be
> 		worth the effort)
>
> Could we agree on this?

Since this is about the new RFC printk design, I've responded in that
thread [0].

John Ogness

[0] https://lkml.kernel.org/r/874l8815uc.fsf@linutronix.de

  reply	other threads:[~2019-03-12 15:19 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-06 14:27 Serial console is causing system lock-up Mikulas Patocka
2019-03-06 15:22 ` Petr Mladek
2019-03-06 16:07   ` Mikulas Patocka
2019-03-06 16:30     ` Theodore Y. Ts'o
2019-03-06 17:11       ` Mikulas Patocka
2019-03-06 22:19         ` Steven Rostedt
2019-03-06 22:43           ` John Ogness
2019-03-07  2:22             ` Sergey Senozhatsky
2019-03-07  8:17               ` John Ogness
2019-03-07  8:25                 ` Sergey Senozhatsky
2019-03-07  8:34                   ` John Ogness
2019-03-07  9:17                     ` Sergey Senozhatsky
2019-03-07 10:37                       ` John Ogness
2019-03-07 12:26                         ` Sergey Senozhatsky
2019-03-07 12:54                           ` Mikulas Patocka
2019-03-07 14:21                           ` John Ogness
2019-03-07 15:35                             ` Petr Mladek
2019-03-12  2:32                             ` Sergey Senozhatsky
2019-03-12  8:17                               ` John Ogness
2019-03-12  8:59                                 ` Sergey Senozhatsky
2019-03-12 10:05                                 ` Mikulas Patocka
2019-03-12 13:19                                   ` John Ogness
2019-03-12 13:44                                     ` Petr Mladek
2019-03-12 12:08                                 ` Petr Mladek
2019-03-12 15:19                                   ` John Ogness [this message]
2019-03-13  2:38                                   ` Sergey Senozhatsky
2019-03-13  8:43                                     ` John Ogness
2019-03-14 10:30                                       ` Sergey Senozhatsky
2019-03-07 14:08             ` John Stoffel
2019-03-07 14:26               ` Mikulas Patocka
2019-03-08  1:22                 ` Sergey Senozhatsky
2019-03-08  1:39                   ` Sergey Senozhatsky
2019-03-08  2:36                     ` John Ogness
2019-03-07 15:16         ` Petr Mladek
2019-03-07  1:56     ` Sergey Senozhatsky
2019-03-07 13:12       ` Mikulas Patocka

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