Messages in this thread | | | Date | Thu, 9 Jun 2005 21:18:42 -0700 | From | Tony Lindgren <> | Subject | Re: [PATCH] Dynamic tick for x86 version 050602-1 |
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* Jonathan Corbet <corbet@lwn.net> [050607 13:36]: > Tony Lindgren <tony@atomide.com> wrote: > > > --- linux-dev.orig/arch/i386/kernel/irq.c 2005-06-01 17:51:36.000000000 -0700 > > +++ linux-dev/arch/i386/kernel/irq.c 2005-06-01 17:54:32.000000000 -0700 > > [...] > > @@ -102,6 +103,12 @@ fastcall unsigned int do_IRQ(struct pt_r > > ); > > } else > > #endif > > + > > +#ifdef CONFIG_NO_IDLE_HZ > > + if (dyn_tick->state & (DYN_TICK_ENABLED | DYN_TICK_SKIPPING) && irq != 0) > > + dyn_tick->interrupt(irq, NULL, regs); > > +#endif > > + > > __do_IRQ(irq, regs); > > Forgive me if I'm being obtuse (again...), but this hunk doesn't look > like it would work well in the 4K stacks case. When 4K stacks are being > used, dyn_tick->interrupt() will only get called in the nested interrupt > case, when the interrupt stack is already in use. This change also > pushes the non-assembly __do_IRQ() call out of the else branch, meaning > that, when the switch is made to the interrupt stack (most of the time), > __do_IRQ() will be called twice for the same interrupt.
Good catch as mentioned earlier :)
> It looks to me like you want to put your #ifdef chunk *after* the call > to __do_IRQ(), unless you have some reason for needing it to happen > before the regular interrupt handler is invoked.
Time needs to be updated before __do_IRQ() so interrupt handlers have correct time.
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