linux-kernel - Re: [RFC][PATCH] printk: increase devkmsg write() ratelimit

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Date:   Tue, 18 Dec 2018 12:29:34 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:     Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Borislav Petkov <bp@...en8.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: Re: [RFC][PATCH] printk: increase devkmsg write() ratelimit

On Tue, Dec 18, 2018 at 08:17:01PM +0900, Sergey Senozhatsky wrote:
> On (12/18/18 11:48), Peter Zijlstra wrote:
> > > I know that there is a "kernel.printk_devkmsg" interface; do we
> > > expect every systemd-enabled distro to find that out and to tweak
> > > kernel.printk_devkmsg or shall we change the default devkmsg
> > > ratelimit instead?
> > 
> > How about we complain to systemd instead?
> 
> We certainly can. As far as I understand, they log shutdown events
> (including errors and warnings): what they kill, what they stop,
> what they umount, etc. The more partitions, services are running
> (I guess), the more things they need to umount, kill, stop; hence,
> the more messages. I kinda can imagine what they will answer ;)
> 
> The below (and a bunch of other) messages are getting ratelimited.
> I'm not sure what will happen should any of those steps fail and
> print warning-s. My guess would be that we probably can ratelimit
> those warnings:

Why are they writing it to /dev/kmsg though? Shouldn't they be writing
this to syslog directly?