Re: [BUG] Threaded printk breaks early debugging

From: Sergey Senozhatsky
Date: Sun Jun 12 2022 - 23:49:16 EST


On (22/06/13 01:08), John Ogness wrote:
> On 2022-06-12, Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx> 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.