Re: [PATCH] FRV: do_gettimeofday() should no longer use tickadj

David Howells
2006-09-06T12:33:44Z

Ingo Molnar <mingo@elte.hu> wrote:

> btw., would be nice to convert it to genirq (and irqchips) too =B-) That
> would solve the kind of disable_irq_lockdep() breakage that was reported
> recently.

I can think of reasons for not using that stuff also.

(1) Passing "struct pt_regs *regs" around is a complete waste of resources on
FRV. It's in GR28 at all times and can thus be accessed directly.

(2) All the little operations functions cause unnecessary jumping, jumps that
icache lookahead can't predict because they're register-indirect.

(3) ACK'ing and controlling interrupts has to be done by groups.

(4) No account is taken of interrupt priority.

(5) The FRV CPU doesn't tell me which IRQ source fired. Much of the code
I've got is stuff to try and work it out. I could just blindly poll all
the sources attached to a particular interrupt level, but that seems
somehow less efficient.

David

BTW, have you looked at my patch to fix lockdep yet?