RE: [Xen-devel] [xen 3.4.2][2.6.31.6-pvops] Problems with cpufreq=xen power management on amd k8 cpu

["Yu, Ke" <ke.yu@xxxxxxxxx>]

Hi Sander,

For option1 "cpufreq=dom0-kernel", it is not working currently, the reason is a 
bit complex, and let me explain. For every processor, there is corresponding 
acpi processor object in ACPI DSDT table. Kernel use struct acpi_processor to 
represent the acpi processor object. There is a field "id" in acpi_processor 
representing the cpu id (the same id as smp_processor_id()). Kernel cpufreq use 
acpi_processor->id to do the frequency scaling. Unfortunately, in pv_ops 
domain0, the acpi_processor->id value is not correct, because it is get by 
acpi_id->apic_id->id mapping, and in pv_ops dom0, the apic_id of vcpu is not 
correctly initialized. Please see drivers/acpi/processor_core.c:get_cpu_id() 
for detail code, where cpu_physical_id() is not initialized in pv_ops dom0 
case. I am still thinking if there is better approach to do the 
acpi_id->apic_id->id mapping in pv_ops dom0 case. 

BTW, "cpufreq=dom0-kernel" is not recommend, due to that it require 
#pCPU=#vCPU, and all vCPU in dom0 must be pined.

For option2 "cpufreq=xen", from the log, Xen can get all the P states info, but 
it failed to do cpufreq cpu initialization 
(xen/arch/x86/acpi/cpufreq/cpufreq.c: cpufreq_cpu_init()), so the cpufreq is 
not started finally, and xenpm cannot set cpufreq parameter. To get more debug 
info, I write a simple patch as attached, could you please have a try and send 
the debug info?

Another thing is, does "cpufreq=xen" work with linux-2.6.18-xen dom0? 

Best Regards
Ke

-----Original Message-----
From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx 
[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Sander Eikelenboom
Sent: Thursday, January 07, 2010 11:08 PM
To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] [xen 3.4.2][2.6.31.6-pvops] Problems with cpufreq=xen 
power management on amd k8 cpu

Hi All,

I'm trying to get powermanagement working with xen and a 2.6.31.6-pvops kernel 
on xen 3.4.2
>From what I have read, I have 2 options:
1) Let the xen hypervisor do the powermanagement (cpufreq=xen)
2) Let the dom0 kernel do the powermanagement    (cpufreq=dom0-kernel)

When booting the 2.6.31.6-pvops kernel on bare metal without hypervisor the 
powernow-k8 module works.
When booting the 2.6.31.6-pvops kernel as dom0 on the xen 3.4.2 hypervisor the 
powernow-k8 module doesn't load and complains:
     Jan  7 15:25:37 localhost kernel: [   12.797914] powernow-k8: Found 1 AMD 
Athlon(tm) Dual Core Processor 4850e processors (2 cpu cores) (version 2.20.00)
     Jan  7 15:25:37 localhost kernel: [   12.797926] powernow-k8: register 
performance failed: bad ACPI data
     Jan  7 15:25:37 localhost kernel: [   12.797929] [Firmware Bug]: 
powernow-k8: No compatible ACPI _PSS objects found.
     Jan  7 15:25:37 localhost kernel: [   12.797931] [Firmware Bug]: 
powernow-k8: Try again with latest BIOS.
     Jan  7 15:25:37 localhost kernel: [   12.797941] powernow-k8: register 
performance failed: bad ACPI data
     Jan  7 15:25:37 localhost kernel: [   12.822315] acpi-cpufreq: 
acpi_cpufreq_init
     Jan  7 15:25:37 localhost kernel: [   12.822319] acpi-cpufreq: 
acpi_cpufreq_early_init
     Jan  7 15:25:37 localhost kernel: [   12.822333] acpi-cpufreq: 
acpi_cpufreq_cpu_init
     Jan  7 15:25:37 localhost kernel: [   12.822338] acpi-cpufreq: 
acpi_cpufreq_cpu_init

It could be that additional changes are needed to the pvops kernel that have 
been made to the xen 2.6.18.8 kernel ?

When trying the first option, and let the hypervisor do the powermanagement 
(booting with cpufreq=xen cpufreq.debug=2 loglvl=all)
it shows the following in xm dmesg (complete xm dmesg attachted):

(XEN) Set CPU acpi_id(0) cpuid(0) Px State info:
(XEN)   _PPC: 0
(XEN) Set CPU acpi_id(0) cpuid(0) Px State info:
(XEN)   _PCT: descriptor=130, length=12, space_id=127, bit_width=0, 
bit_offset=0, reserved=0, address=0
(XEN)   _PCT: descriptor=130, length=12, space_id=127, bit_width=0, 
bit_offset=0, reserved=0, address=0
(XEN)   _PSS: state_count=6
(XEN)   State0: 2500MHz 50000mW 100us 9us 0xe8201391 0x391
(XEN)   State1: 2400MHz 46020mW 100us 9us 0xe82013d0 0x3d0
(XEN)   State2: 2200MHz 38671mW 100us 9us 0xe820144e 0x44e
(XEN)   State3: 2000MHz 32100mW 100us 9us 0xe82014cc 0x4cc
(XEN)   State4: 1800MHz 26265mW 100us 9us 0xe820154a 0x54a
(XEN)   State5: 1000MHz 13888mW 100us 9us 0xe8201582 0x582
(XEN)   _PSD: num_entries=5 rev=0 domain=0 coord_type=253 num_processors=2
(XEN)   _PPC: 0
(XEN) Set CPU acpi_id(1) cpuid(1) Px State info:
(XEN)   _PPC: 0
(XEN) Set CPU acpi_id(1) cpuid(1) Px State info:
(XEN)   _PCT: descriptor=130, length=12, space_id=127, bit_width=0, 
bit_offset=0, reserved=0, address=0
(XEN)   _PCT: descriptor=130, length=12, space_id=127, bit_width=0, 
bit_offset=0, reserved=0, address=0
(XEN)   _PSS: state_count=6
(XEN)   State0: 2500MHz 50000mW 100us 9us 0xe8201391 0x391
(XEN)   State1: 2400MHz 46020mW 100us 9us 0xe82013d0 0x3d0
(XEN)   State2: 2200MHz 38671mW 100us 9us 0xe820144e 0x44e
(XEN)   State3: 2000MHz 32100mW 100us 9us 0xe82014cc 0x4cc
(XEN)   State4: 1800MHz 26265mW 100us 9us 0xe820154a 0x54a
(XEN)   State5: 1000MHz 13888mW 100us 9us 0xe8201582 0x582
(XEN)   _PSD: num_entries=5 rev=0 domain=0 coord_type=253 num_processors=2
(XEN)   _PPC: 0

So it seems to find all available powerstates, but using xenpm doesn't seem to 
work:

serveerstertje:~# xenpm  get-cpu-topology
CPU     core    socket
CPU0     0       0
CPU1     1       0
serveerstertje:~# xenpm  set-scaling-governor userspace
[CPU0] failed to set governor name
[CPU1] failed to set governor name
serveerstertje:~# xenpm  set-scaling-governor ondemand
[CPU0] failed to set governor name
[CPU1] failed to set governor name
serveerstertje:~# xenpm  set-scaling-governor performance
[CPU0] failed to set governor name
[CPU1] failed to set governor name
serveerstertje:~# xenpm  set-scaling-governor powersave
[CPU0] failed to set governor name
[CPU1] failed to set governor name
serveerstertje:~# xenpm  get-cpufreq-para
[CPU0] failed to get cpufreq parameter
[CPU1] failed to get cpufreq parameter


-- 
Best regards,
 Sander                          mailto:linux@xxxxxxxxxxxxxx

Attachment: cpufreq.patch
Description: cpufreq.patch

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