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    SubjectRe: 2.6.24-rc6-git12: Reported regressions from 2.6.23
    Date
    On Sunday, 6 of January 2008, Arjan van de Ven wrote:
    > On Sun, 6 Jan 2008 10:55:01 +0100
    > Ingo Molnar <mingo@elte.hu> wrote:
    >
    > >
    > > * Mark Lord <lkml@rtr.ca> wrote:
    > >
    > > > Rafael J. Wysocki wrote:
    > > >> This message contains a list of some regressions from 2.6.23
    > > >> reported since 2.6.24-rc1 was released, for which there are no
    > > >> fixes in the mainline I know of. If any of them have been fixed
    > > >> already, please let me know.
    > > > ..
    > > >> Subject : 20000+ wake-ups/second in 2.6.24
    > > >> Submitter : Mark Lord <lkml@rtr.ca>
    > > >> Date : 2007-12-02 04:23
    > > >> References : http://lkml.org/lkml/2007/12/1/141
    > > >> http://bugzilla.kernel.org/show_bug.cgi?id=9489
    > > >> Handled-By : Arjan van de Ven <arjan@infradead.org>
    > > >>
    > > >
    > > > I wonder if it's just a babbling IRQ on resume, before the driver
    > > > has run it's resume code or something ?
    > >
    > > i've read the discussions, and i cannot see it analyzed anywhere
    > > _what_ causes the wakeups. And how are these wakeups counted? Is this
    > > based on powertop output:
    > >
    > > Wakeups-from-idle per second : 20.4 interval: 1.8s
    > >
    > > ? Somewhere i saw it mentioned that "the CPU throws out of C mode".
    > > What does that mean - does it mean we try to idle again and again,
    > > but we immediately return from C mode - while this all looks like
    > > "idle" time to the scheduler (so 'top' will show lots of idle time),
    > > but the ACPI wakeup counters are going up like mad? What
    > > is /proc/interrupts doing when this happens - is any of the irq
    > > sources going upwards?
    > >
    >
    > what seems to happen (and this is based on seeing this on my own devel laptop, as well
    > as several other reports; Mark is by far not the only one) is something hardware
    > related, it's been seen on lots of different kernel versions.
    >
    > It seems to mostly (but not 100%) happen with TI cardbus bridges, where for some reason,
    > once the yenta driver is loaded (unloading it later makes no difference), once in a while
    > we get into a mode where the CPU always immediately goes out of the C-state again.
    > On a hardware level, there are only a few things that cause a CPU to exit a C-state,
    > and one of them is a pending interrupt of some kind, which is the most likely thing going on here;
    > some device or apic being stuck with interrupt high, but somehow the CPU isn't actually
    > seeing the interrupt itself (or has it blocked!)
    >
    > To call this a 2.6.24 regression is a mistake (as I've said before), it's not new to .24
    > by any means.

    Thanks for the explanation, I'm removing this from the regressions list, then.

    Greetings,
    Rafael


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