On Sun, 6 Jan 2008 10:55:01 +0100 Ingo Molnar <[EMAIL PROTECTED]> wrote:
> > * Mark Lord <[EMAIL PROTECTED]> 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 <[EMAIL PROTECTED]> > >> 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 <[EMAIL PROTECTED]> > >> > > > > 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. -- If you want to reach me at my work email, use [EMAIL PROTECTED] For development, discussion and tips for power savings, visit http://www.lesswatts.org -- 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/
