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Date: Thu, 11 Jan 2018 14:35:07 +0900
From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Subject: Re: [PATCH v5 0/2] printk: Console owner and waiter logic cleanup
Message-ID: <20180111053507.GD494@jagdpanzerIV>
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To: Steven Rostedt <rostedt@goodmis.org>
Cc: Tejun Heo <tj@kernel.org>, Petr Mladek <pmladek@suse.com>, Sergey Senozhatsky <sergey.senozhatsky@gmail.com>, akpm@linux-foundation.org, linux-mm@kvack.org, Cong Wang <xiyou.wangcong@gmail.com>, Dave Hansen <dave.hansen@intel.com>, Johannes Weiner <hannes@cmpxchg.org>, Mel Gorman <mgorman@suse.de>, Michal Hocko <mhocko@kernel.org>, Vlastimil Babka <vbabka@suse.cz>, Peter Zijlstra <peterz@infradead.org>, Linus Torvalds <torvalds@linux-foundation.org>, Jan Kara <jack@suse.cz>, Mathieu Desnoyers <mathieu.desnoyers@efficios.com>, Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>, rostedt@home.goodmis.org, Byungchul Park <byungchul.park@lge.com>, Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>, Pavel Machek <pavel@ucw.cz>, linux-kernel@vger.kernel.org

On (01/10/18 14:17), Steven Rostedt wrote:
[..]
> OK, lets start over.

good.

> Right now my focus is an incremental approach. I'm not trying to solve
> all issues that printk has. I've focused on a single issue, and that is
> that printk is unbounded. Coming from a Real Time background, I find
> that is a big problem. I hate unbounded algorithms.

agreed! so why not bound it to watchdog threshold then? why bound
it to a random O(logbuf) thing? which is not even constant. when you
un-register or disable one or several consoles then call_console_drivers()
becomes faster; when you register/enable consoles then the entire
call_console_drivers() becomes slower. how do we build a reliable
algorithm on that O(logbuf)?

	-ss

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