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From: Petr Mladek <pmladek@suse.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	akpm@linux-foundation.org, linux-mm@kvack.org,
	Peter Zijlstra <peterz@infradead.org>, Jan Kara <jack@suse.cz>,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	Tejun Heo <tj@kernel.org>,
	linux-kernel@vger.kernel.org,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Subject: Re: [PATCH] printk: Ratelimit messages printed by console drivers
Date: Mon, 23 Apr 2018 14:45:02 +0200	[thread overview]
Message-ID: <20180423124502.423fb57thvbf3zet@pathway.suse.cz> (raw)
In-Reply-To: <20180423073603.6b3294ba@gandalf.local.home>

On Mon 2018-04-23 07:36:03, Steven Rostedt wrote:
> On Mon, 23 Apr 2018 12:32:32 +0200
> Ug, you're right. Somehow when I looked at where console_owner was set
> "console_lock_spinning_enabled" I saw it as "console_trylock_spinning".
> 
> This is what I get when I'm trying to follow three threads at the same
> time :-/

They are not easy to follow :-/

> > console_owner is really set only between:
> > 
> >     console_lock_spinning_enable()
> >     console_lock_spinning_disable_and_check()
> > 
> > and this entire section is called with interrupts disabled.
> 
> OK, I agree with you now. Although, one hour may still be too long.

I am not sure how slow are the slowest consoles. If I take that
everything should be faster than 1200 bauds. Then 10 minutes
should be enough for 1000 lines and 80 characters per-line:

   1000*80*8/1200/60 = 8.8888888


Alternatively, it seems that we are going to call console drivers
outside printk_safe context => the messages will appear in the main
log buffer immediately => only small risk of a ping-pong with printk
safe buffers. We might reset the counter when all messages are handled
in console_unlock(). It will be more complex patch than when using
ratelimiting but it still should be sane.

Neither solution is perfect. But I think that the recursion is not
worth any too complex solution.

Best Regards,
Petr

  reply	other threads:[~2018-04-23 12:45 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-13 12:47 Petr Mladek
2018-04-13 14:12 ` Steven Rostedt
2018-04-14  2:35   ` Sergey Senozhatsky
2018-04-16  1:47     ` Sergey Senozhatsky
2018-04-16  4:25       ` Sergey Senozhatsky
2018-04-19 12:53         ` Petr Mladek
2018-04-20  2:15           ` Sergey Senozhatsky
2018-04-20  9:12             ` Petr Mladek
2018-04-20 12:04               ` Steven Rostedt
2018-04-20 14:01                 ` Petr Mladek
2018-04-20 14:17                   ` Steven Rostedt
2018-04-20 14:19                     ` Steven Rostedt
2018-04-20 14:57                     ` Petr Mladek
2018-04-20 15:13                       ` Steven Rostedt
2018-04-23 10:32                         ` Petr Mladek
2018-04-23 11:36                           ` Steven Rostedt
2018-04-23 12:45                             ` Petr Mladek [this message]
2018-04-25  5:31                               ` Sergey Senozhatsky
2018-04-26  9:42                                 ` Petr Mladek
2018-04-27 10:22                                   ` Sergey Senozhatsky
2018-05-09 12:00                                     ` Petr Mladek
2018-05-09 12:59                                       ` Steven Rostedt
2019-02-26 10:24                                       ` Tetsuo Handa
2019-02-28  4:45                                         ` Sergey Senozhatsky
2018-04-23  5:21               ` Sergey Senozhatsky
2018-04-23 12:26                 ` Petr Mladek
2018-04-23 13:00                   ` Sergey Senozhatsky

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