* Pallipadi, Venkatesh <[email protected]> [050608 15:14]:
>
> >-----Original Message-----
> >From: [email protected]
> >[mailto:[email protected]] On Behalf Of
> >Jonathan Corbet
> >Sent: Tuesday, June 07, 2005 1:36 PM
> >To: Tony Lindgren
> >Cc: [email protected]
> >Subject: Re: [PATCH] Dynamic tick for x86 version 050602-1
> >
> >Tony Lindgren <[email protected]> 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.
> >
> >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.
> >
>
> Good catch. This indeed looks like a bug.
> With 050602-1 version I am seeing double the number of calls to
> timer_interrupt routine than expected. Say, when all CPUs are fully
> busy,
> I see 2*HZ timer interrupt count in /proc/interrupts
>
> And things look normal once I change this hunk as below
>
> >> } 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);
> + }
Cool. Sorry for not responding earlier, my hard drive crashed yesterday
morning... I also managed to fry my spare computer's motherboard
while trying to recover some data from the broken disk :)
I'll try to post an updated patch tomorrow.
Tony
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
