From: Petr Mladek <pmladek@suse.com>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Calvin Owens <calvinowens@fb.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jonathan Corbet <corbet@lwn.net>,
linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org
Subject: Re: [PATCH 1/4] printk: Introduce per-console loglevel setting
Date: Wed, 20 Mar 2019 16:37:29 +0100 [thread overview]
Message-ID: <20190320153729.6cl77kdck22vc4rv@pathway.suse.cz> (raw)
In-Reply-To: <c7a9c83c-524d-c0da-a355-6cd4b7ec690c@I-love.SAKURA.ne.jp>
On Thu 2019-03-14 23:12:49, Tetsuo Handa wrote:
> Petr Mladek wrote:
> > It might be even more straightforward when the per-console value
> > defines the effective console level. I mean the following semantic:
> >
> > + "console_loglevel" would define the default loglevel used
> > by consoles at runtime.
> >
> > + the per-console loglevel could override the default
> > console_loglevel.
> >
> > + We would need a custom handler for the sysctl "console_loglevel".
> > It would write the given value to the global console_loglevel
> > variable and for all already registered consoles (con->loglevel).
>
> But some functions change console_loglevel without sysctl (e.g.
> console_verbose() when reporting hung tasks and panic()). Should
> con->loglevel be changed (which might result in too much messages to
> slow consoles) when console_loglevel changes?
It is about the semantic. We either want to set a hard limit
for each console or we want to set per-console loglevel that
will get used in normal situations.
I prefer the 2nd semantic. IMHO, console_verbose() should be
used only in situations when people really want to see all
lines, for example, panic, sysrq output when the machine
looks deadlocked, ignore_loglevel is set. I believe that they
want to see them even on the slow consoles that are
there exactly for debugging these critical situations.
Best Regards,
Petr
next prev parent reply other threads:[~2019-03-20 15:37 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-02 0:48 [RFC][PATCH 0/4] Per-console loglevel support, console device bus Calvin Owens
2019-03-02 0:48 ` [PATCH 1/4] printk: Introduce per-console loglevel setting Calvin Owens
2019-03-08 3:10 ` Sergey Senozhatsky
2019-03-12 21:00 ` Calvin Owens
2019-03-08 15:09 ` Petr Mladek
2019-03-14 14:12 ` Tetsuo Handa
2019-03-20 15:37 ` Petr Mladek [this message]
2019-03-02 0:48 ` [PATCH 2/4] printk: Add ability to set loglevel via "console=" cmdline Calvin Owens
2019-03-08 15:44 ` Petr Mladek
2019-03-02 0:48 ` [PATCH 3/4] printk: Add consoles to a virtual "console" bus Calvin Owens
2019-03-08 2:56 ` John Ogness
2019-03-08 15:58 ` Petr Mladek
2019-03-08 16:34 ` Greg Kroah-Hartman
2019-03-12 20:44 ` Calvin Owens
2019-03-08 15:53 ` Petr Mladek
2019-03-12 20:52 ` Calvin Owens
2019-03-11 13:33 ` Petr Mladek
2019-03-12 21:52 ` Calvin Owens
2019-03-13 10:08 ` Petr Mladek
2019-03-02 0:48 ` [PATCH 4/4] printk: Add a device attribute for the per-console loglevel Calvin Owens
2019-03-04 8:06 ` Sergey Senozhatsky
2019-03-04 19:10 ` Calvin Owens
2019-03-08 3:11 ` Sergey Senozhatsky
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