linux-kernel - Re: [RFC][PATCHv6 00/12] printk: introduce printing kernel thread

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Message-ID: <20171218133948.GD31274@jagdpanzerIV>
Date:   Mon, 18 Dec 2017 22:39:48 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Tejun Heo <tj@...nel.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Jan Kara <jack@...e.cz>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Rafael Wysocki <rjw@...ysocki.net>,
        Pavel Machek <pavel@....cz>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCHv6 00/12] printk: introduce printing kernel thread

On (12/18/17 14:31), Petr Mladek wrote:
> On Mon 2017-12-18 18:36:15, Sergey Senozhatsky wrote:
> > On (12/15/17 10:08), Petr Mladek wrote:
> > 1) it opens both soft and hard lockup vectors
> > 
> >    I see *a lot* of cases when CPU that call printk in a loop does not
> >    end up flushing its messages. And the problem seems to be - preemption.
> > 
> > 
> >   CPU0						CPU1
> > 
> >   for_each_process_thread(g, p)
> >     printk()
> 
> You print one message for each process in a tight loop.
> Is there a code like this?

um... show_state() -> show_state_filter()?
which prints million times more info than a single line per-PID.

	-ss