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 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.
>
> Depends on:
> 1. What you're trying to do.
> 2. What your programs are optimized for.
> 3. Additional factors (I/O, load, etc).
> 4. Hardware attached to each machine. Some examples...
>   a. Comparing a SCSI disk vs a PATA disk.
>   b. Clockspeed applied to the RAM on one machine isn't equal to the other.
>   c. Motherboard manufacturers -- some manufacturers have done a shoddy job
> with memory handling, BIOS manufacturing, and other critical stats in the
> past.
>
> Try disabling ACPI on the P4 though and see what happens. I will say though,
> the Willamette (1st gen P4) chips weren't Intel's finest desktop chip; some
> people went far enough to complain that the Willamette series was nothing
> more than overclocked Coppermines, i.e. P3's. I haven't taken a look at the
> architectures and compared them, so those may be empty claims.

I was wondering about the "truth-of-clockspeed."  Perhaps the 1800-MHz only applies to CPU internal cache, etc. while the external bus-clocking is down at 500-MHz or so.  Sounds like a typical marketing ploy!

About disabling the ACPI...  Can I do it *safely* via the remote-ssh connection?  Or do I need to be at the box w/ keyboard and monitor?  What I've read makes it seem that the ACPI is set at boot-time.