On Tue, Nov 29, 2016 at 06:10:38PM +0100, Peter Zijlstra wrote:
> On Tue, Nov 29, 2016 at 05:29:20PM +0100, Petr Mladek wrote:
>
> > > > People are very busy polishing the turd we call printk, but from where
> > > > I'm sitting its terminally and unfixably broken.
> >
> > I still hope that we could do better :-)
>
> How? The console drivers are a complete trainwreck, you simply cannot
> build anything sensible ontop of a trainwreck.
>
> And from what I understood from talking to someone (I again forgot who)
> at LPC, the whole reason people were poking at this is that the block
> layer (or something thereabouts) prints a gazillion lines of crap when
> you attach a stupid amount of devices (through FC or other SAN like
> things).
>
> The way we've 'fixed' that in the scheduler (a fairly long time ago)
> when SGI complained about our printks taking too long (because they had
> 4096 CPUs), is to simply remove the printks (they're now hidden behind
> the sched_debug boot param).
>
>
> In any case, as long as printk has a globally serialized 'log', it, per
> design, will be worse than the console drivers its build upon. And them
> being shit precludes the entire stack from being useful.
>
> It mostly works, most of the time, and that seems to be what Linus
> wants, since its really the best we can have given the constraints. But
> for debugging, when you have a UART, it totally blows.
UART??? They still make those things??? ;-)
Thanx, Paul
