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

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Ondrej Zary wrote:

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.
Ok I stand corrected, I had no idea there were machines that old where ACPI worked correctly in Linux.
Do you see the same kind of heat reduction in Linux as Win98? What HZ value are you using, as the latency for entering C2 on your machine looks pretty substantial (Your C2 almost looks like a new machine's C3 state, which is supposedly the first level where substantial power savings occur on a new machines). 

 - Jim Bruce
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