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

From: Ondrej Zary
Date: Tue Aug 02 2005 - 11:16:41 EST


James Bruce wrote:
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).

rainbow@pentium:~$ cat /proc/acpi/processor/CPU0/power
active state: C2
max_cstate: C8
bus master activity: 00000000
states:
C1: type[C1] promotion[C2] demotion[--] latency[000] usage[00052470]
*C2: type[C2] promotion[--] demotion[C1] latency[090] usage[02699149]


This is PCPartner TXB820DS motherboard (Socket 7, i430TX) with 1998 Award BIOS and C-states seem to work fine. I've tested it in Windows 98 some time ago - the CPU is almost cold when idle with ACPI enabled and hot with ACPI disabled (that's partly caused by the fact that Windows 9x does not HLT the CPU when idle). With Pentium 100MHz in the socket and ACPI enabled, I could even touch the CPU (without heatsink) without burning my fingers.

--
Ondrej Zary
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