linux-kernel - Re: [RFC][PATCH v4 0/2] printk: Make printk() completely async

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Date:	Sun, 24 Apr 2016 14:03:11 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:	Pavel Machek <pavel@....cz>
Cc:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jan Kara <jack@...e.com>, Petr Mladek <pmladek@...e.com>,
	Tejun Heo <tj@...nel.org>,
	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	linux-kernel@...r.kernel.org,
	Byungchul Park <byungchul.park@....com>,
	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Subject: Re: [RFC][PATCH v4 0/2] printk: Make printk() completely async

Hi,

On (04/23/16 21:36), Pavel Machek wrote:
> >  The patch set is based on slightly updated Jan Kara's patches.
> > 
> > This patch set makes printk() completely asynchronous: new messages
> > are getting upended to the kernel printk buffer, but instead of 'direct'
> > printing the actual print job is performed by a dedicated kthread.
> > This has the advantage that printing always happens from a schedulable
> > context and thus we don't lockup any particular CPU or even
> > interrupts.
> 
> And that means that printk() will become mostly useless for debugging,
> right?

what do you mean? printk by default operates in 'old' sync mode
and can be switched to async for those who experience problems
with the sync one (whilst actually debugging). I'm not sure I
got your point.

	-ss