linux-kernel - [PATCH 0/3] PM / sleep: Avoid filling up kernel log buffer with debug messages

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Message-ID: <2539550.y54cRb749c@aspire.rjw.lan>
Date:   Wed, 19 Jul 2017 02:37:24 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Linux PM <linux-pm@...r.kernel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 0/3] PM / sleep: Avoid filling up kernel log buffer with debug messages

Hi,

The problem at hand is that on some systems suspend-to-idle can easily fill up
the kernel log buffer with debug messages in one cycle (if spurious wakeups
happen ofter enough).

I tried to make that somewhat better before, but it still turns out to be
problematic, so here's a patch series to possibly address this.

[1/3] adds a sysfs knob to turn debug messages from the core suspend/hibernate
code on and off (default) and a printk() wrapper taking that into account.

[2/3] adds some "info" messages to indicate when system power transitions start
and finish which IMO is useful to see in the log regardless.

[3/3] modifies the wrapper introduced by [1/3] to make it suitable for
tk_debug_account_sleep_time() and uses it in there instead of the
plain printk_deferred() as that also is a debug thing really and can
fill up the log buffer by itself in some cases.

Thanks,
Rafael