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From: Mandeep Singh Baines <msb@chromium.org>
To: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Randy Dunlap <rdunlap@xenotime.net>,
	Mandeep Singh Baines <msb@chromium.org>,
	linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	olofj@chromium.org
Subject: Re: [PATCH] printk: allow setting DEFAULT_MESSAGE_LEVEL via Kconfig
Date: Thu, 27 Jan 2011 07:57:54 -0800	[thread overview]
Message-ID: <20110127155754.GB8520@google.com> (raw)
In-Reply-To: <20110127082718.GA4748@p183.telecom.by>

Alexey Dobriyan (adobriyan@gmail.com) wrote:
> On Wed, Jan 26, 2011 at 03:10:17PM -0800, Andrew Morton wrote:
> > On Wed, 26 Jan 2011 14:57:03 -0800
> > Randy Dunlap <rdunlap@xenotime.net> wrote:
> > 
> > > > I'm a bit surprised that this wasn't already tunable at boot-time
> > > > and/or at runtime.
> > > 
> > > 
> > > As WANG Cong replied:
> > > 
> > > Why? We already have "loglevel=" kernel parameter.
> > 
> > That's different.
> > 
> > Mandeep's patch addresses printks which didn't have a facility level. 
> 
> For those, we have ignore_loglevel kernel parameter.

That's a little different. ignore_loglevel will print ALL kernel messages
to the console. What we would like to do is look at all messages that
are KERN_WARNING (and higher in priority) very closely. Bugs lie there;)
Problem is that DEFAULT_MESSAGE_LEVEL is KERN_WARNING so there is too
much noise at KERN_WARNING. So we'd like to be able to set
DEFAULT_MESSAGE_LEVEL (default_message_loglevel) to something lower in,
priority, at boot or earlier. You can set it via /proc/sys/kernel/printk
(takes an int_vec) but that's too late. A ton of stuff has already been
logged by the time we're able to change a sysctl.

Our plan is to whitelist any KERN_WARNING messages we know are OK and
flag any new KERN_WARNING messages. We're hoping this will help us cut
down on regressions. We've been burned in the past where we caused a
regression which tooks weeks to locate and triage only to later learn
that there was a new KERN_WARNING that if we hadn't ignored would have
caught the bug much much earlier.

  reply	other threads:[~2011-01-27 16:01 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-01-25 23:57 [PATCH] printk: allow setting DEFAULT_MESSAGE_LEVEL via Kconfig Mandeep Singh Baines
2011-01-26  0:40 ` Joe Perches
2011-01-26  1:01   ` Mandeep Singh Baines
2011-01-26  1:15     ` Joe Perches
2011-01-26  4:18 ` WANG Cong
2011-01-26 23:05   ` Mandeep Baines
2011-01-27  5:49     ` WANG Cong
2011-01-26 22:49 ` Andrew Morton
2011-01-26 22:57   ` Randy Dunlap
2011-01-26 23:10     ` Andrew Morton
2011-01-27  7:26       ` WANG Cong
2011-01-27  8:27       ` Alexey Dobriyan
2011-01-27 15:57         ` Mandeep Singh Baines [this message]
2011-01-27 20:45           ` Ryan Mallon
2011-01-27 20:53             ` Alexey Dobriyan
2011-01-27 20:57               ` Ryan Mallon
2011-01-26 23:29 ` [PATCH v1 0/6] Set printk priority level Mandeep Singh Baines
2011-01-27  7:22   ` WANG Cong
2011-01-26 23:29 ` [PATCH 1/6] mm/page_alloc: use appropriate " Mandeep Singh Baines
2011-01-27  0:32   ` Ryan Mallon
2011-01-27  4:22     ` Mandeep Singh Baines
2011-01-27 20:32       ` Ryan Mallon
2011-01-26 23:29 ` [PATCH 2/6] arch/x86: " Mandeep Singh Baines
2011-01-26 23:29 ` [PATCH 3/6] PM: " Mandeep Singh Baines
2011-01-31 10:12   ` Rafael J. Wysocki
2011-01-26 23:29 ` [PATCH 4/6] TTY: " Mandeep Singh Baines
2011-02-03 22:13   ` Greg KH
2011-02-06 17:31     ` [PATCH v2] " Mandeep Singh Baines
2011-01-26 23:29 ` [PATCH 5/6] fs: " Mandeep Singh Baines
2011-01-26 23:29 ` [PATCH 6/6] taskstats: " Mandeep Singh Baines

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