Re: Power-Mgt (Was: Re: cvs commit: src/sys/i386/cpufreq est.c )


On Mon, 17 Mar 2008, Poul-Henning Kamp wrote:

In message <47DED21C.4070108@xxxxxxxxxxx>, Kris Kennaway writes:

I think this is a great idea, but one of the big problems is probably going to be dealing with hardware quirks. e.g. we can't even enable powerd by default because e.g. acpi_throttle hangs on some systems. It might be tricky to get power management to the stage where it works for everyone and can be done automatically.

I'd expect that this will improve over time, just like all other technologies from ISA to PCI bus implementations did.

But yes, it will take time & effort, but given the current cleantech/greentech buzz, I think we'd better get moving.

I know we've talked about this, but I'll mention it for the benefits of the mailing list: one of the things that makes performance an "easy" target is that there are easy-to-gather metrics. Those metrics may require knowledge of statistics and a lifetime of experience to interpret correctly, but they are still numbers that are easily generated and compared. To drive work in power management, we would benefit from having similarly accessible metrics. Are there any decent documents describing how to do power use measurement, and are there any (relatively) accessible tools for doing it with? For example, on notebooks, can we sample an ACPI value before/after a benchmark, or do we really need to hook something up to the power supply in order to get a useful number?

Robert N M Watson
Computer Laboratory
University of Cambridge
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