CPU frequency doesn't drop below 1200MHz (like it used to)
Adrian Chadd
adrian at freebsd.org
Sat May 23 15:15:56 UTC 2015
Hm, no thermal monitoring and no speedstep. Could be dangerous/fun.
What's the output of sysctl dev.cpu.0 ?
-adrian
On 23 May 2015 at 07:40, Kimmo Paasiala <kpaasial at gmail.com> wrote:
> On Sat, May 23, 2015 at 5:15 PM, Ian Smith <smithi at nimnet.asn.au> wrote:
>> On Sat, 23 May 2015 14:01:16 +0300, Kimmo Paasiala wrote:
>> > On Sat, May 23, 2015 at 10:00 AM, Ian Smith <smithi at nimnet.asn.au> wrote:
>> > > On Fri, 22 May 2015 20:26:40 +0300, Kimmo Paasiala wrote:
>> > > > On Fri, May 22, 2015 at 8:19 PM, Ian Smith <smithi at nimnet.asn.au> wrote:
>> > > > > On Fri, 22 May 2015 16:28:49 +0300, Kimmo Paasiala wrote:
>> > > > > > On Fri, May 22, 2015 at 10:42 AM, Ivan Klymenko <fidaj at ukr.net> wrote:
>> > > [..]
>> > > > >> Try changing the options in /boot/device.hints
>> > > > >> hint.acpi_throttle.0.disabled="0"
>> > > > >> hint.p4tcc.0.disabled="0"
>> > > > >
>> > > > > > Thanks, those also fixed powerd(8) for me that stopped working after
>> > > > > > upgrading to stable/10 from releng/10.1. Why are those setting
>> > > > > > suddenly needed now?
>> > > [..]
>> > > > > Can you say exactly in what way powerd stopped working then?
>> > > >
>> > > > Powerd(8) complained (excerpt from dmesg -a):
>> > > >
>> > > > Starting powerd.
>> > > > powerd: no cpufreq(4) support -- aborting: No such file or directory
>> > > > /etc/rc: WARNING: failed to start powerd
>> > > >
>> > > > Putting those two settings in loader.conf and rebooting fixed the
>> > > > problem and powerd started working again apparently because cpufreq(4)
>> > > > device was available again.
>> > >
>> > > Ok, if anabling acpi_throttle and/or p4tcc made cpufreq - and thus
>> > > powerd - work for you, then it seems likely that you do not have EST
>> > > enabled in your BIOS. Or at least, we've seen another instance where
>> > > that was the case, which was fixed by enabling EST (or however your
>> > > particular BIOS refers to it .. AMD for example use different terms).
>> > >
>> > > What CPU is this? In what machine?
>> > >
>> > > If EST (ono) IS enabled in your BIOS, this needs further investigation.
>> > >
>> > > As is, powerd may be running, but it's doing so highly inefficiently;
>> > > refer to Stefan, Adrian and Kevin's responses for details.
>>
>> > It's an Intel Atom running amd64 version of FreeBSD stable/10:
>> >
>> > FreeBSD firewall.rdnzl.info 10.1-STABLE FreeBSD 10.1-STABLE #1
>> > r283292: Sat May 23 01:08:03 EEST 2015
>> > root at firewall.rdnzl.info:/usr/obj/usr/src/sys/GENERIC amd64
>> >
>> > CPU: Intel(R) Atom(TM) CPU D510 @ 1.66GHz (1666.68-MHz K8-class CPU)
>> > Origin="GenuineIntel" Id=0x106ca Family=0x6 Model=0x1c Stepping=10
>> > Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
>> > Features2=0x40e31d<SSE3,DTES64,MON,DS_CPL,TM2,SSSE3,CX16,xTPR,PDCM,MOVBE>
>> > AMD Features=0x20100800<SYSCALL,NX,LM>
>> > AMD Features2=0x1<LAHF>
>> > TSC: P-state invariant, performance statistics
>> >
>> > Powerd was working on 10.1-RELEASE but stopped working after upgrade
>> > to 10-STABLE and nothing was changed in BIOS settings.
>>
>> Which would be consistent with EST not being enabled in your BIOS; with
>> no EST, cpufreq(4) still checks for 'relative' drivers such as p4tcc or
>> acpi_throttle and uses that, as a last resort really; with those also
>> disabled, no cpufreq, so no powerd. Have you checked BIOS settings to
>> confirm that you do have SpeedStep (however termed) properly enabled?
>>
>> Please show `sysctl dev.cpu dev.est` and `sysctl -a | grep freq_levels`
>>
>> > However, reading the other replies to this thread I get the impression
>> > that powerd(8) doesn't actually save energy on this platform and I'm
>> > better off without it?
>>
>> No, I don't think that's correct; using deeper C-states is most likely a
>> bigger win, but higher than needed CPU freq will still use extra power,
>> so run hotter. `sysctl dev.cpu` will also reveal your C-state usage.
>>
>> Reason I'm pursuing this is that this change shouldn't hurt, but it will
>> flush out those cases where people were only getting cpufreq due to use
>> of a 'relative' cpufreq driver like p4tcc, unless EST's enabled in BIOS;
>> I suspect yours may be one such case :) If not, there's a bug to fix.
>>
>> cheers, Ian
>
> Looking deeper into this it appears I don't have speedstep (EST)
> support in the CPU it being a crappy Atom D510:
>
> http://ark.intel.com/products/43098
>
> This the full 'sysctl dev.cpu' output:
>
> % sysctl dev.cpu
> dev.cpu.3.cx_usage: 100.00% last 65712us
> dev.cpu.3.cx_lowest: C1
> dev.cpu.3.cx_supported: C1/1/0
> dev.cpu.3.%parent: acpi0
> dev.cpu.3.%pnpinfo: _HID=none _UID=0
> dev.cpu.3.%location: handle=\_PR_.P004
> dev.cpu.3.%driver: cpu
> dev.cpu.3.%desc: ACPI CPU
> dev.cpu.2.cx_usage: 100.00% last 41518us
> dev.cpu.2.cx_lowest: C1
> dev.cpu.2.cx_supported: C1/1/0
> dev.cpu.2.%parent: acpi0
> dev.cpu.2.%pnpinfo: _HID=none _UID=0
> dev.cpu.2.%location: handle=\_PR_.P003
> dev.cpu.2.%driver: cpu
> dev.cpu.2.%desc: ACPI CPU
> dev.cpu.1.cx_usage: 100.00% last 12706us
> dev.cpu.1.cx_lowest: C1
> dev.cpu.1.cx_supported: C1/1/0
> dev.cpu.1.%parent: acpi0
> dev.cpu.1.%pnpinfo: _HID=none _UID=0
> dev.cpu.1.%location: handle=\_PR_.P002
> dev.cpu.1.%driver: cpu
> dev.cpu.1.%desc: ACPI CPU
> dev.cpu.0.cx_usage: 100.00% last 3132us
> dev.cpu.0.cx_lowest: C1
> dev.cpu.0.cx_supported: C1/1/0
> dev.cpu.0.%parent: acpi0
> dev.cpu.0.%pnpinfo: _HID=none _UID=0
> dev.cpu.0.%location: handle=\_PR_.P001
> dev.cpu.0.%driver: cpu
> dev.cpu.0.%desc: ACPI CPU
> dev.cpu.%parent:
>
> So I should keep those two hints in loader.conf to use p4tcc I guess?
>
> -Kimmo
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