Re: Power consumption HZ100, HZ250, HZ1000: new numbers

From: James Bruce
Date: Tue Aug 02 2005 - 10:48:15 EST


Stephen Clark wrote:
Maybe new desktop systems - but what about the tens of millions of old systems that don't.

If it's an old system, it probably doesn't have working ACPI C-states though. Without that, low HZ does not save you anything. I should have said: 99% of desktops with the capability to do ACPI sleep have at least one USB device attached (usually a mouse).

I do like saving power, which is why I run cpu frequency scaling on every machine I have that supports it. I'm happy because it does its savings without negatively impacting latency or high-load performance. By 2.6.14 dyntick should give us the same thing for HZ, which is why I think changing the maximum value now doesn't make sense.

- Jim Bruce
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