Re: [RFC][PATCHv4 0/7] printk: introduce printing kernel threads

[Sergey Senozhatsky]

On (06/30/17 14:11), Petr Mladek wrote:
> > 2) can offload printing to other CPUs from vprintk_emit()
> >    and avoid any of scheduler->timekeeping->etc. paths. which will
> >    replace printk_deferred().
> 
> I probably miss something. There is still called wake_up_process()
> in this patchset and we could not do this in some scheduler and
> timekeeping paths. Also we must not take the console_lock() in
> these paths because it calls wake_up_process() as well. But
> we want to flush few lines when possible.

yes. but we could call wake_up_process() on !this_cpu.
so we wouldn't take this_cpu ->rq lock and so on.

	CPU1

	vprintk_emit()
		wake_up_process(printk_kthread on CPU2);

	-ss