Re: [PATCH 3/9] printk: add CON_ALLDATA console flag

Jeff Moyer
2013-03-01T15:08:15Z

Borislav Petkov <bp@alien8.de> writes:

> On Fri, Mar 01, 2013 at 09:52:27AM -0500, Jeff Moyer wrote:
>> > For consoles like netconsole and blockconsole the loglevel filtering
>> > really doesn't make any sense. If a line gets printed at all, please
>> > send it down to that console, no questions asked.
>>
>> Could you please explain this a bit further? Why wouldn't you want to
>> allow the admin to filter log messages to the block or network console?
>> This doesn't make a whole lot of sense to me, and in fact could cause
>> problems for netconsole now that you're potentially sending a ton more
>> traffic over the wire.
>
> Let's reverse the question: why would the admin ever want to filter
> messages to debugging consoles like netconsole or blockconsole?
>
> When running a debugging session, you generally want to see *all*
> messages.

People don't just use this for "debugging sessions." They use it in
production, and I already gave you one reason why you might not want to
do this with netconsole (udp is unreliable, and I've definitely seem
cases where netconsole suffered due to dropped packets; this won't make
that better, especially when you multiply the extra bytes times the
number of servers on the subnet).

Cheers,
Jeff