Powerd and est / eist functionality
smithi at nimnet.asn.au
Fri Mar 26 04:24:25 UTC 2010
On Wed, 24 Mar 2010, John Long wrote:
> At 11:27 PM 3/22/2010, Alexander Motin wrote:
> >John Long wrote:
> >> Hello, I am putting together a couple update servers. Went with c2d
> >> E7500 on gigabyte G41M-ES2L boards. fbsd 8.0 release generic (so far)
> >> amd64, 1g mem, 1tb wd cavier blk, fresh system.
> >> My Kill-a-watt shows 41 watts idle and when I enable powerd then it
> >> climbs to 43 watts idle.
I'm interested in this apparently strange finding. Can you show sysctl
dev.cpu after boot but before running powerd, and after starting powerd?
I wonder particularly what dev.cpu.o.freq is before running powerd, ie
whether it boots up at full speed? We've seen some that haven't,
perhaps influenced by BIOS settings?
Turning on debug.cpufreq.verbose and hw.acpi.verbose may add clues?
> >> It shows that the freq is controlled well, goes down to 365 mhz but
> >> the tdp is not decreased, rather it increases.
Yes you're only getting p4tcc throttling as Alexander points out. You'll
need to get est working to get power reduction from lower frequencies,
which likely won't correspond to these f/8 step throttling frequencies.
As Jeremy suggested, here's how to turn throttling off, and something
like what you could expect with est working:
> >> If I disable eist, c1 and c3 helpers in bios, as per suggestion in
> >> mail archive, then it adds 1 watt to both figures. I was hoping to get
> >> this total tdp down to a very low amount, and it is but it should
> >> theoretically go lower with powerd, right?
If powerd were actually reducing frequency (and voltage) via est it
certainly would. Finding out why est is failing to attach on your
hardware is the only likely path to success, try focusing on that and
ignoring side issues. Have you browsed freebsd-acpi archives re this?
> >> load 3%, current freq 365 MHz ( 7), wanted freq 365 MHz
> >> load 0%, current freq 365 MHz ( 7), wanted freq 365 MHz
> >Your ACPI BIOS seems not reporting tables required to control EIST. So
> >powerd probably uses only thermal throttling, which is not really
> >effective for power saving on modern CPUs. You should check your BIOS
> >options or may be update BIOS.
> >If you have no luck with EIST - try to use C-states if BIOS reports at
> >least them. It also can be quite effective.
> >Alexander Motin
> Thanks for the info, I did try to kick it to C3 and that helped poquito
> amount. Everything is enabled in bios that matters to this, that does help a
> little too but powerd actually raises tdp a little. See other recent reply
> for more info.
Have you tried C2? Are you running the latest BIOS? And perhaps your
ACPI ASL may be amenable to repair, if Gigabyte ACPI is broken here?
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