ACPI slowing CPU... or something else

[V.I.Victor]

On Wed, 25 Jul 2007 youshi10 at u.washington.edu wrote:

>On Wed, 25 Jul 2007, V.I.Victor wrote:
>
>> On Wed, 25 Jul 2007, Garrett Cooper wrote:
>>
>>> V.I.Victor wrote:
>>>>  I've two 5.4 desktop boxes.  Pretty much the same installation; both
>>>>  from the same CD, same apps, no monitor/keyboard, 1-user logged-on via
>>>>  ssh (command-line only w/no gui) and otherwise lightly loaded.
>>>>
>>>>  Box_A: CPU: AMD-K7(tm) Processor (598.84-MHz 686-class CPU)
>>>>         avail memory = 121630720 (115 MB)
>>>>         ACPI disabled by blacklist.
>>>>
>>>>  Box_B: CPU: Intel(R) Pentium(R) 4 CPU 1.80GHz (1794.19-MHz 686-class CPU)
>>>>         avail memory = 252186624 (240 MB)
>>>>         cpu0: <ACPI CPU> on acpi0
>>>>         acpi_throttle0: <ACPI CPU Throttling> on cpu0
>>>> ...
>>
>>> Yes. On my virtual machine with ACPI:
>>>
>>> dev.cpu.0.freq: 2653
>>> dev.cpu.0.freq_levels: 2653/-1 2321/-1 1989/-1 1658/-1 1326/-1 994/-1 663/-1
>>> 331/-1
>>>
>>> [root at optimus-vm-7 ~]# dmesg | grep 26
>>> FreeBSD 7.0-CURRENT #5: Tue Jul 17 08:22:26 UTC 2007
>>> CPU: Intel(R) Core(TM)2 CPU          6700  @ 2.66GHz (2666.79-MHz K8-class
>>> CPU)
>>> Timecounter "TSC" frequency 2666794890 Hz quality 800
>>>
>>> What are the following sysctls set to?
>>>
>>> kern.clockrate
>>> hw.acpi.cpu.cx_lowest
>>> dev.cpu.0.cx_lowest
>>> dev.cpu.0.cx_usage
>>
>> Thanks for the reply!  I don't seem to have the last 2 you've asked about.
>>
>> 'sysctl -a | egrep "clockrate|cpu"' reported the following:
>>
>> kern.clockrate: { hz = 100, tick = 10000, profhz = 1024, stathz = 128 }
>> kern.threads.virtual_cpu: 1
>> kern.ccpu: 1948
>> kern.smp.maxcpus: 1
>> kern.smp.cpus: 1
>> hw.ncpu: 1
>> hw.clockrate: 1794
>> hw.acpi.cpu.cx_supported: C1/0
>> hw.acpi.cpu.cx_lowest: C1
>> hw.acpi.cpu.cx_usage: 100.00%
>> machdep.cpu_idle_hlt: 1
>> dev.cpu.0.%desc: ACPI CPU
>> dev.cpu.0.%driver: cpu
>> dev.cpu.0.%location: handle=\_PR_.CPU0
>> dev.cpu.0.%pnpinfo: _HID=none _UID=0
>> dev.cpu.0.%parent: acpi0
>> dev.cpu.0.freq: 1796
>> dev.cpu.0.freq_levels: 1796/-1 1571/-1 1347/-1 1122/-1 898/-1 673/-1 449/-1 224/-1
>> dev.acpi_throttle.0.%parent: cpu0
>> dev.cpufreq.0.%driver: cpufreq
>> dev.cpufreq.0.%parent: cpu0
>
>
>
> Do you have SMP enabled? 

No.  Both boxes have pretty minimal, basic installations.

> You also might be able to tune the kernel clock rate to obtain better
> performance; I forget what the values were for sysctl, but if you search
> around the current@ archives a bit, there was a discussion involving VMware
> and clock tuning approximately 2-3 months ago which details this issue, and
> possible solutions.

Perhaps tuning could help.  I'll check the archives.

However, it just seems to me that the 1.8 GHz box ought to perform the simple prog (orig post) at least as fast as the 6 MHz box.