Re: printk meeting at LPC

[Sergey Senozhatsky]

On (09/16/19 12:46), Petr Mladek wrote:
> Hmm, it seems that journalctl is able to filer device specific
> information, for example, I get:
> 
> $> journalctl _KERNEL_DEVICE=+usb:2-1
> -- Logs begin at Tue 2019-08-13 09:00:03 CEST, end at Mon 2019-09-16 12:32:58 CEST. --
> Aug 13 09:00:04 linux-qszd kernel: usb 2-1: new high-speed USB device number 2 using ehci-pci
> 
> One question is if anyone is using this filtering. Simple grep is
> enough. Another question is whether it really needs to get passed
> this way.

Hmm. If I recall correctly...

There was some sort of discussion (and a patch, I believe) a long time
ago. If I'm not mistaken, guys at facebook somehow add "machine ID"
(e.g. CONFIG_DEFAULT_HOSTNAME?) to kernel messages (via dicts). This
has one interesting use case: net consoles print extended headers.

So they have monitoring systems, which capture and track net consoles
output from many servers, and should one of them warn/oom/etc. they
immediately know which one of the machines is "under the weather"
(ext_text directly points at the right server).

Well, once again, if I recall this correctly.

	-ss