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Date:   Wed, 18 Sep 2019 18:11:00 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To:     John Ogness <john.ogness@linutronix.de>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Petr Mladek <pmladek@suse.com>,
        Andrea Parri <parri.andrea@gmail.com>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Brendan Higgins <brendanhiggins@google.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Theodore Ts'o <tytso@mit.edu>, Paul Turner <pjt@google.com>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        Prarit Bhargava <prarit@redhat.com>
Subject: Re: printk meeting at LPC
Message-ID: <20190918091100.GA55364@jagdpanzerIV>
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On (09/18/19 11:05), John Ogness wrote:
> On 2019-09-18, Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> wrote:
> >> Each console has its own iterator. This iterators will need to
> >> advance, regardless if the message was printed via write() or
> >> write_atomic().
> >
> > Great.
> >
> > ->atomic_write() path will make sure that kthread is parked or will
> > those compete for uart port?
> 
> A cpu-lock (probably per-console) will be used to synchronize the
> two. Unlike my RFCv1, we want to keep the cpu-lock out of the console
> drivers and we want it to be less aggressive (using trylock's instead of
> spinning).

That's my expectation as well. cpu-lock and per-console kthread can
live just fine in printk.c file.

	-ss