Dmitry Sivachenko wrote:
On 22 марта 2015 г., at 8:53, Peter Jeremy <pe...@rulingia.com>
wrote:
On 2015-Mar-22 00:58:55 +0300, Dmitry Sivachenko
<trtrmi...@gmail.com> wrote:
I have a machine with the following processor:
CPU: Intel(R) Xeon(R) CPU E5620 @ 2.40GHz (2400.14-MHz
K8-class CPU) Origin="GenuineIntel" Id=0x206c2 Family=0x6
Model=0x2c Stepping=2
...
After I upgraded to 10.1-STABLE #0 r279956, this sysctl
disapeared. % sysctl dev.cpu.0.freq sysctl: unknown oid
'dev.cpu.0.freq': No such file or directory %
What OIDs do you have? Does dev.cpu.0 exist? How about dev.cpu?
dev.cpu.0 does exist.
It could be helpful to show all of:
% sysctl dev.cpu
% sysctl dev.est # if you have that?
% sysctl -a | grep freq | grep -v time
both before and after re-enabling p4tcc.
I found the problematic change:
Author: nwhitehorn Date: Sun Jan 11 17:10:07 2015 New Revision:
276986 URL: https://svnweb.freebsd.org/changeset/base/276986
Log: MFC r265329: Disable ACPI and P4TCC throttling by default,
following discussion on freebsd-current. These CPU speed control
techniques are usually unhelpful at best. For now, continue building
the relevant code into GENERIC so that it can trivially be re-enabled
at runtime if anyone wants it.
Modified: stable/10/sys/amd64/conf/GENERIC.hints
==============================================================================
--- stable/10/sys/amd64/conf/GENERIC.hints Sun Jan 11 17:00:24 2015
(r276985) +++ stable/10/sys/amd64/conf/GENERIC.hints Sun Jan 11
17:10:07 2015 (r276986) @@ -31,3 +31,5 @@ hint.attimer.0.at="isa"
hint.attimer.0.port="0x40" hint.attimer.0.irq="0"
hint.wbwd.0.at="isa" +hint.acpi_throttle.0.disabled="1"
+hint.p4tcc.0.disabled="1"
If I remove that hint.p4tcc.0.disabled="1" from device.hints,
dev.cpu.0.freq appears back again.
'Trivial re-enabling' would be adding hint.p4tcc.0.disabled="0" to
/boot/loader.conf. This seems very strange though, if it really is
due solely to disabling p4tcc and acpi_throttle.
I am using dev.cpu.0.freq to ensure that processor is running at
expected frequency (with some buggy BIOSes or buggy BIOS options
combinations it is possible to end up with machine running at half
frequency).
Are you not running powerd? Of course powerd won't start if it can't
get dev.cpu.0.freq but you can ordinarily use it to set lowest and/or
highest freqs. Once FreeBSD starts, BIOS settings should have little
do with it, AFAIK, except how they might set freq before powerd starts.
Does it really hurt to have this sysctl available? Why it was
disabled by default?
It's a long story; (a) short story is using it to vary freqs doesn't
save any power, but makes powerd work harder matching freq to load.
(I am not discussing hint.acpi_throttle.0.disabled here, just
hint.p4tcc.0.disabled).
Some or many systems will use ACPI throttling instead if p4tcc (or
equivalent on AMD or other processors) isn't enabled, so they both
need disabling to run 'raw' EST or equivalent.
A link to a verbose boot would be good, before and after if possible.
cheers, Ian
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