Messages in this thread | | | Subject | Re: [PATCH] i386 No Idle HZ aka dynticks 051221 | Date | Mon, 26 Dec 2005 18:47:10 +0000 | From | Matthew Garrett <> |
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Theodore Ts'o <tytso@mit.edu> wrote:
> With dyntick enabled, the laptop never enters the C4 state, but > instead bounces back and forth between C2 and C3 (and I notice that we > never enter C1 state, even when the CPU is completely pegged, but > that's true with or without dyntick).
C1 is a power-saving mode - if your CPU is pegged, you won't be in any C state (the acpi code seems to make this confusing by showing you the last mode you were in - however, the usage count won't change). If the C2 latency isn't significantly larger than the C1 latency, I don't think there's ever any reason to want to use C1.
To further confuse things, the ipw2100 driver will silently disable anything higher than C2 if it ever receives a corrupt packet. I'm not convinced this is a good thing. -- Matthew Garrett | mjg59-chiark.mail.linux-rutgers.kernel@srcf.ucam.org - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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