Re: IRQ off latency of printk is very high

Benny Amorsen
2007-10-26T12:57:33Z

>>>>> "MM" == Matt Mackall <mpm@selenic.com> writes:

MM> Well there are things we can do, yes, but I'd be worried that
MM> they've give up the deterministic behavior we rely on quite
MM> heavily for debugging. If event A happens before event B, we must
MM> see the message from A before the one from B, even if B happens in
MM> irq context.

MM> And if event B is a hard lock up, we'd also like to be sure the
MM> message for A actually gets out. If B happens in the interrupt
MM> that comes in when we re-enable them, that won't happen.

I can see the concerns, but right now it all leads to disabling serial
console for real-time servers. That is even less helpful for
debugging.

/Benny