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From: Sergey Senozhatsky <senozhatsky@chromium.org>
To: John Ogness <john.ogness@linutronix.de>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>,
	Petr Mladek <pmladek@suse.com>, Peter Geis <pgwipeout@gmail.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"open list:ARM/Rockchip SoC..."
	<linux-rockchip@lists.infradead.org>
Subject: Re: [BUG] Threaded printk breaks early debugging
Date: Mon, 13 Jun 2022 12:49:03 +0900	[thread overview]
Message-ID: <Yqazr060OLp2Rpbk@google.com> (raw)
In-Reply-To: <8735g9mqo0.fsf@jogness.linutronix.de>

On (22/06/13 01:08), John Ogness wrote:
> On 2022-06-12, Sergey Senozhatsky <senozhatsky@chromium.org> wrote:
> > Should a situation when we have only one online CPU be enough of a
> > reason to do direct printing? Otherwise we might not have CPUs to
> > wakeup khtread on, e.g. when CPU that printk is in atomic section for
> > too long.
> 
> IMHO, no. Especially in that situation, we do not want printk causing
> that atomic section to become even longer. If the machine has entered
> normal operation, we want printk out of the way.

At the same time printk throttles itself in such cases: new messages are
not added at much higher pace that they are printed at. So we lower the
chances of missing messages.

_______________________________________________
Linux-rockchip mailing list
Linux-rockchip@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-rockchip

WARNING: multiple messages have this Message-ID (diff)
From: Sergey Senozhatsky <senozhatsky@chromium.org>
To: John Ogness <john.ogness@linutronix.de>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>,
	Petr Mladek <pmladek@suse.com>, Peter Geis <pgwipeout@gmail.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"open list:ARM/Rockchip SoC..."
	<linux-rockchip@lists.infradead.org>
Subject: Re: [BUG] Threaded printk breaks early debugging
Date: Mon, 13 Jun 2022 12:49:03 +0900	[thread overview]
Message-ID: <Yqazr060OLp2Rpbk@google.com> (raw)
In-Reply-To: <8735g9mqo0.fsf@jogness.linutronix.de>

On (22/06/13 01:08), John Ogness wrote:
> On 2022-06-12, Sergey Senozhatsky <senozhatsky@chromium.org> wrote:
> > Should a situation when we have only one online CPU be enough of a
> > reason to do direct printing? Otherwise we might not have CPUs to
> > wakeup khtread on, e.g. when CPU that printk is in atomic section for
> > too long.
> 
> IMHO, no. Especially in that situation, we do not want printk causing
> that atomic section to become even longer. If the machine has entered
> normal operation, we want printk out of the way.

At the same time printk throttles itself in such cases: new messages are
not added at much higher pace that they are printed at. So we lower the
chances of missing messages.

  reply	other threads:[~2022-06-13  3:49 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-10 12:48 [BUG] Threaded printk breaks early debugging Peter Geis
2022-06-10 12:48 ` Peter Geis
2022-06-10 15:05 ` John Ogness
2022-06-10 15:05   ` John Ogness
2022-06-10 15:34   ` Peter Geis
2022-06-10 15:34     ` Peter Geis
2022-06-12  2:57     ` Sergey Senozhatsky
2022-06-12  2:57       ` Sergey Senozhatsky
2022-06-12 13:30       ` Peter Geis
2022-06-12 13:30         ` Peter Geis
2022-06-12 23:08     ` John Ogness
2022-06-12 23:08       ` John Ogness
2022-06-12 23:30       ` Peter Geis
2022-06-12 23:30         ` Peter Geis
2022-06-13  2:23         ` John Ogness
2022-06-13  2:23           ` John Ogness
2022-06-13 15:11           ` Petr Mladek
2022-06-13 15:11             ` Petr Mladek
2022-06-13 22:20             ` Peter Geis
2022-06-13 22:20               ` Peter Geis
2022-06-14  8:38               ` Petr Mladek
2022-06-14  8:38                 ` Petr Mladek
2022-06-13 11:24         ` Petr Mladek
2022-06-13 11:24           ` Petr Mladek
2022-06-12  3:13   ` Sergey Senozhatsky
2022-06-12  3:13     ` Sergey Senozhatsky
2022-06-12 23:02     ` John Ogness
2022-06-12 23:02       ` John Ogness
2022-06-13  3:49       ` Sergey Senozhatsky [this message]
2022-06-13  3:49         ` Sergey Senozhatsky
2022-06-13  8:30         ` John Ogness
2022-06-13  8:30           ` John Ogness
2022-06-13  9:05           ` Sergey Senozhatsky
2022-06-13  9:05             ` Sergey Senozhatsky
2022-06-13 10:14             ` Petr Mladek
2022-06-13 10:14               ` Petr Mladek
2022-06-13 16:11               ` David Laight
2022-06-13 16:11                 ` David Laight
2022-06-14  8:37                 ` Petr Mladek
2022-06-14  8:37                   ` Petr Mladek

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