Rafael Vanoni wrote:
>
> It depends. For instance, writing a lot to disk shows a lower wakeup
> count than events:
>
> Wakeups-from-idle per second: 1566.7 interval: 2.0s
> no ACPI power usage estimate available
>
> Top causes for wakeups:
> 88.4% (1384.6) <interrupt> : pci-ide#0
> 9.5% (149.3) <kernel> : uhci`uhci_handle_root_hub_status_change
> 7.7% (120.4) <interrupt> : nvidia#0
> 4.4% ( 68.2) java : <scheduled timeout expiration>
> 4.3% ( 66.7) <kernel> : ehci`ehci_handle_root_hub_status_change
> 4.3% ( 66.7) <kernel> : genunix`clock
> 2.1% ( 33.3) <kernel> : genunix`cyclic_timer
> 0.9% ( 13.9) <kernel> : genunix`lwp_timer_timeout
>
Right, because there's a DTrace probe that's firing when we get an
interrupt for the pci-ide#0 device...but that doesn't necessarily result
in an idle CPU waking up. :) It's a similar issue to the cyclics being
batched processed.
> While sitting idle shows a higher wakeup count:
>
> Wakeups-from-idle per second: 562.7 interval: 2.0s
> no ACPI power usage estimate available
>
> Top causes for wakeups:
> 26.5% (149.3) <kernel> : uhci`uhci_handle_root_hub_status_change
> 21.5% (120.9) <interrupt> : nvidia#0
> 12.2% ( 68.7) java : <scheduled timeout expiration>
> 11.8% ( 66.7) <kernel> : ehci`ehci_handle_root_hub_status_change
> 10.3% ( 57.7) <kernel> : genunix`cyclic_timer
> 7.5% ( 42.3) <kernel> : genunix`clock
> 2.7% ( 15.4) thunderbird-bin : <scheduled timeout expiration>
> 2.4% ( 13.4) <kernel> : genunix`lwp_timer_timeout
>
This makes me wonder if there's a way that we could dig around to see,
when the idle-state-transition probe fires (because we're coming out of
halt/mwait/etc), to see what's waking us up (rather then trying to
correlate wakeups with events elsewhere in the system).
It's probably a short list...either:
- Device interrupt
- cyclic apic timer related firing
- cross call (poke) from another CPU because something became runnable
If we can figure out which of the above things is responsible for the
idle-state-transition, and can then get information about the thing that
happened:
- Which device
- which cyclic is due
- what became runnable
...and then have powertop report that...that should get us pretty close,
I would think.
What do you think?
Thanks,
-Eric
-Eric
> thanks
> Rafael
>
>
>
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