Hello everyone, I am running some experiments that require changing the frequency of a CPU in a SunFire machine (32-core quad socket AMD Barcelona). For what I have found (bits and pieces but not a comprehensive description), there are two meachisms for controlling core (most probably socket) frequency in Xen: A- The older (xen-3.2.1) mechnism through dom0 (option cpufreq=dom0-kernel), which for what I gather uses a module in dom0 (cpufreqd?) that allows one to set cpu frequency. B- The newer (xen-3.3), which has moved the governor to the hypervisor (option cpufreq=xen), which other than a utility to read processor P and C states (xenpm) does not (yet) allow user (dom0) control of CPU frequency. My first question is whetherot what I have written above is accurate. My second question is where can I find detailed information on how to set up my system to make use of A above and be able to set cpu frequency "manually" from Dom0 (assuming that is still possible in Xen 3.3). I am running the latest testing version of Xen 3.3 (about a week old). Any information would be greatly appreciated. Thank you, Alberto _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Your description is basically correct. Do you want to control cpu frequency from dom0 user level, or just try cpufreq governor in dom0? For the former, we''re currently adding more flexibility to xen cpufreq (such as user space governor) and control options to xenpm (such as manually changing freq), which is expected to reach xen upstream soon. For the latter, it''s suboptimal with limitations which is why xen cpufreq is develeoped. You may manually disable PROCESSOR_EXTERNAL_CONTROL in drivers/acpi/Kconfig to rebuild dom0 kernel for mode A. Thanks, Kevin ________________________________ From: xen-users-bounces@lists.xensource.com [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of Alberto Munoz Sent: Thursday, November 20, 2008 2:50 AM To: xen-users@lists.xensource.com Subject: [Xen-users] Setting CPU (core) frequency from dom0 Hello everyone, I am running some experiments that require changing the frequency of a CPU in a SunFire machine (32-core quad socket AMD Barcelona). For what I have found (bits and pieces but not a comprehensive description), there are two meachisms for controlling core (most probably socket) frequency in Xen: A- The older (xen-3.2.1) mechnism through dom0 (option cpufreq=dom0-kernel), which for what I gather uses a module in dom0 (cpufreqd?) that allows one to set cpu frequency. B- The newer (xen-3.3), which has moved the governor to the hypervisor (option cpufreq=xen), which other than a utility to read processor P and C states (xenpm) does not (yet) allow user (dom0) control of CPU frequency. My first question is whetherot what I have written above is accurate. My second question is where can I find detailed information on how to set up my system to make use of A above and be able to set cpu frequency "manually" from Dom0 (assuming that is still possible in Xen 3.3). I am running the latest testing version of Xen 3.3 (about a week old). Any information would be greatly appreciated. Thank you, Alberto _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Alberto Munoz
2008-Nov-20 18:38 UTC
Re: [Xen-users] Setting CPU (core) frequency from dom0
Hi Kevin, Thank you very much for the reply. PLease see comments below. Alberto On Wed, Nov 19, 2008 at 7:05 PM, Tian, Kevin <kevin.tian@intel.com> wrote:> Your description is basically correct. Do you want to control cpu > frequency from dom0 user level, or just try cpufreq governor in dom0? >I would like to control frequency from dom0. I want to arbitrarily set the CPU frequency to a value and have it stay there (regardless of the load on that CPU) until I change it. For the former, we''re currently adding more flexibility to xen cpufreq (such> as user space governor) and control options to xenpm (such as manually > changing freq), which is expected to reach xen upstream soon. >Yes, I thik this is what I need (ability to manually change frequency). Do you have an ETA (estimated time of arrival) for that functionality?> For the latter, it''s suboptimal with limitations which is why xen cpufreq > is develeoped. You may manually disable PROCESSOR_EXTERNAL_CONTROL in > drivers/acpi/Kconfig to rebuild dom0 kernel for mode A. >OK. I will do that. By the way, I have been running onto an error when booting (in mode A). The function cpufreq_time_setup() in linux-2.6.18-xen.hg/arch/i386/kernel/time-xen.c is printing the following message during boot (and returning -ENODEV to its caller): *failed to set up cpufreq notifier* Further examination of the code shows that this happens when notifier_chain_register() in linux-2.6.18-xen.hg/kernel/sys.c returns 0. The problem is that in the code I have, that function ALWAYS returns 0. The code for that function is as follows: static int notifier_chain_register(struct notifier_block **nl, struct notifier_block *n) { while ((*nl) != NULL) { if (n->priority > (*nl)->priority) break; nl = &((*nl)->next); } n->next = *nl; rcu_assign_pointer(*nl, n); return 0; } think (but are not 100% sure yet) that as a result of this error, dom0 is not creating a cpufreq /sys interface (i.e Do you happen to know what may be going on? perhaps I am just misreading the code? or perhaps not disabling PROCESSOR_EXTERNAL_CONTROL is what is causing this behavior? I will run some experiments on this last thing today. Thanks again, Alberto> Thanks, > Kevin > > ------------------------------ > *From:* xen-users-bounces@lists.xensource.com [mailto: > xen-users-bounces@lists.xensource.com] *On Behalf Of *Alberto Munoz > *Sent:* Thursday, November 20, 2008 2:50 AM > *To:* xen-users@lists.xensource.com > *Subject:* [Xen-users] Setting CPU (core) frequency from dom0 > > Hello everyone, > > I am running some experiments that require changing the frequency of a CPU > in a SunFire machine (32-core quad socket AMD Barcelona). > > For what I have found (bits and pieces but not a comprehensive > description), there are two meachisms for controlling core (most probably > socket) frequency in Xen: > > A- The older (xen-3.2.1) mechnism through dom0 (option > cpufreq=dom0-kernel), which for what I gather uses a module in dom0 > (cpufreqd?) that allows one to set cpu frequency. > > B- The newer (xen-3.3), which has moved the governor to the hypervisor > (option cpufreq=xen), which other than a utility to read processor P and C > states (xenpm) does not (yet) allow user (dom0) control of CPU frequency. > > My first question is whetherot what I have written above is accurate. My > second question is where can I find detailed information on how to set up my > system to make use of A above and be able to set cpu frequency "manually" > from Dom0 (assuming that is still possible in Xen 3.3). > > I am running the latest testing version of Xen 3.3 (about a week old). > > Any information would be greatly appreciated. > > Thank you, > > Alberto > > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
ETA can be in one or two weeks, and now coding is close to end (by Jinsong).
This patch sets will cover many control bits besides allowing user to change
freq as I said earlier.
For the code you mentioned, it''s one bug since as you cited that
return-0 means success. However it looks that this warning doesn''t hurt
the behavior:
if (!cpufreq_register_notifier(&time_cpufreq_notifier_block,
CPUFREQ_TRANSITION_NOTIFIER)) {
printk(KERN_ERR "failed to set up cpufreq
notifier\n");
return -ENODEV;
}
return 0;
Notifier is registered successfully and there''s no code to reverse the
effect even when -ENODEV is returned. :-) BTW in xen3.2, there''s no
PROCESSOR_EXTERNAL_CONTROL.
Thanks,
Kevin
________________________________
From: xen-users-bounces@lists.xensource.com
[mailto:xen-users-bounces@lists.xensource.com] On Behalf Of Alberto Munoz
Sent: Friday, November 21, 2008 2:39 AM
To: Tian, Kevin
Cc: bmunoz@acm.org; xen-users@lists.xensource.com
Subject: Re: [Xen-users] Setting CPU (core) frequency from dom0
Hi Kevin,
Thank you very much for the reply.
PLease see comments below.
Alberto
On Wed, Nov 19, 2008 at 7:05 PM, Tian, Kevin
<kevin.tian@intel.com<mailto:kevin.tian@intel.com>> wrote:
Your description is basically correct. Do you want to control cpu frequency from
dom0 user level, or just try cpufreq governor in dom0?
I would like to control frequency from dom0. I want to arbitrarily set the CPU
frequency to a value and have it stay there (regardless of the load on that
CPU) until I change it.
For the former, we''re currently adding more flexibility to xen cpufreq
(such as user space governor) and control options to xenpm (such as manually
changing freq), which is expected to reach xen upstream soon.
Yes, I thik this is what I need (ability to manually change frequency). Do you
have an ETA (estimated time of arrival) for that functionality?
For the latter, it''s suboptimal with limitations which is why xen
cpufreq is develeoped. You may manually disable PROCESSOR_EXTERNAL_CONTROL in
drivers/acpi/Kconfig to rebuild dom0 kernel for mode A.
OK. I will do that.
By the way, I have been running onto an error when booting (in mode A). The
function cpufreq_time_setup() in
linux-2.6.18-xen.hg/arch/i386/kernel/time-xen.c is printing the following
message during boot (and returning -ENODEV to its caller):
failed to set up cpufreq notifier
Further examination of the code shows that this happens when
notifier_chain_register() in linux-2.6.18-xen.hg/kernel/sys.c returns 0. The
problem is that in the code I have, that function ALWAYS returns 0. The code for
that function is as follows:
static int notifier_chain_register(struct notifier_block **nl,
struct notifier_block *n)
{
while ((*nl) != NULL) {
if (n->priority > (*nl)->priority)
break;
nl = &((*nl)->next);
}
n->next = *nl;
rcu_assign_pointer(*nl, n);
return 0;
}
think (but are not 100% sure yet) that as a result of this error, dom0 is not
creating a cpufreq /sys interface (i.e
Do you happen to know what may be going on? perhaps I am just misreading the
code? or perhaps not disabling PROCESSOR_EXTERNAL_CONTROL is what is causing
this behavior? I will run some experiments on this last thing today.
Thanks again,
Alberto
Thanks,
Kevin
________________________________
From:
xen-users-bounces@lists.xensource.com<mailto:xen-users-bounces@lists.xensource.com>
[mailto:xen-users-bounces@lists.xensource.com<mailto:xen-users-bounces@lists.xensource.com>]
On Behalf Of Alberto Munoz
Sent: Thursday, November 20, 2008 2:50 AM
To: xen-users@lists.xensource.com<mailto:xen-users@lists.xensource.com>
Subject: [Xen-users] Setting CPU (core) frequency from dom0
Hello everyone,
I am running some experiments that require changing the frequency of a CPU in a
SunFire machine (32-core quad socket AMD Barcelona).
For what I have found (bits and pieces but not a comprehensive description),
there are two meachisms for controlling core (most probably socket) frequency in
Xen:
A- The older (xen-3.2.1) mechnism through dom0 (option cpufreq=dom0-kernel),
which for what I gather uses a module in dom0 (cpufreqd?) that allows one to set
cpu frequency.
B- The newer (xen-3.3), which has moved the governor to the hypervisor (option
cpufreq=xen), which other than a utility to read processor P and C states
(xenpm) does not (yet) allow user (dom0) control of CPU frequency.
My first question is whetherot what I have written above is accurate. My second
question is where can I find detailed information on how to set up my system to
make use of A above and be able to set cpu frequency "manually" from
Dom0 (assuming that is still possible in Xen 3.3).
I am running the latest testing version of Xen 3.3 (about a week old).
Any information would be greatly appreciated.
Thank you,
Alberto
_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com<mailto:Xen-users@lists.xensource.com>
http://lists.xensource.com/xen-users
_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users
Alberto Munoz
2008-Nov-21 16:47 UTC
Re: [Xen-users] Setting CPU (core) frequency from dom0
Hi Kevin, On Thu, Nov 20, 2008 at 7:02 PM, Tian, Kevin <kevin.tian@intel.com> wrote:> ETA can be in one or two weeks, and now coding is close to end (by > Jinsong). This patch sets will cover many control bits besides allowing user > to change freq as I said earlier. >Excellent! How do I find out when the patch has been made available?> > For the code you mentioned, it''s one bug since as you cited that return-0 > means success. However it looks that this warning doesn''t hurt the behavior: > if (!cpufreq_register_notifier(&time_cpufreq_notifier_block, > CPUFREQ_TRANSITION_NOTIFIER)) { > printk(KERN_ERR "failed to set up cpufreq notifier\n"); > return -ENODEV; > } > return 0; > > Notifier is registered successfully and there''s no code to reverse the > effect even when -ENODEV is returned. :-) >Yes, I figured that out yesterday. Other than printing the error, the system does nothing with the -ENODEV return. Still, I am not getting a sysfs interface for cpufreq and I haven''t been able to figure out why.> BTW in xen3.2, there''s no PROCESSOR_EXTERNAL_CONTROL. >In case this was not clear, I am trying to use method A (cpufreq=dom0-kernel) with Xen 3.3 (not 3.2). Does that not work in Xen 3.3? Also, do you happen to know of a place where I can get a list of what needs to be set up in order to get this frequency scaling to work. I am pretty sure that my problem with not getting the sysfs interface for cpufreq (it is available for other things) is related to something I am missing in the configuration. So far, what I have done (for method A) is: - Set the option cpufreq=dom0-kernel as an option to the Xen hypervisor (in grub) - Disable PROCESSOR_EXTERNAL_CONTROL in drivers/acpi/Kconfig (for dom0) - Enable CONFIG_CPU_FREQ for dom0 (I did this from arch/x86_64/Kconfig) Perhaps there is a BIOS setting for the CPU that I am unaware of (my machine is using Barcelona CPUs)? Thank you, Alberto> > Thanks, > Kevin > > ------------------------------ > *From:* xen-users-bounces@lists.xensource.com [mailto: > xen-users-bounces@lists.xensource.com] *On Behalf Of *Alberto Munoz > *Sent:* Friday, November 21, 2008 2:39 AM > *To:* Tian, Kevin > *Cc:* bmunoz@acm.org; xen-users@lists.xensource.com > *Subject:* Re: [Xen-users] Setting CPU (core) frequency from dom0 > > Hi Kevin, > > Thank you very much for the reply. > > PLease see comments below. > > Alberto > > On Wed, Nov 19, 2008 at 7:05 PM, Tian, Kevin <kevin.tian@intel.com> wrote: > >> Your description is basically correct. Do you want to control cpu >> frequency from dom0 user level, or just try cpufreq governor in dom0? >> > > I would like to control frequency from dom0. I want to arbitrarily set the > CPU frequency to a value and have it stay there (regardless of the load on > that CPU) until I change it. > > For the former, we''re currently adding more flexibility to xen cpufreq >> (such as user space governor) and control options to xenpm (such as manually >> changing freq), which is expected to reach xen upstream soon. >> > > Yes, I thik this is what I need (ability to manually change frequency). Do > you have an ETA (estimated time of arrival) for that functionality? > > >> For the latter, it''s suboptimal with limitations which is why xen >> cpufreq is develeoped. You may manually disable PROCESSOR_EXTERNAL_CONTROL >> in drivers/acpi/Kconfig to rebuild dom0 kernel for mode A. >> > > OK. I will do that. > > By the way, I have been running onto an error when booting (in mode A). > The function cpufreq_time_setup() in > linux-2.6.18-xen.hg/arch/i386/kernel/time-xen.c is printing the following > message during boot (and returning -ENODEV to its caller): > > *failed to set up cpufreq notifier* > > Further examination of the code shows that this happens when > notifier_chain_register() in linux-2.6.18-xen.hg/kernel/sys.c returns 0. The > problem is that in the code I have, that function ALWAYS returns 0. The code > for that function is as follows: > > static int notifier_chain_register(struct notifier_block **nl, > struct notifier_block *n) > { > while ((*nl) != NULL) { > if (n->priority > (*nl)->priority) > break; > nl = &((*nl)->next); > } > n->next = *nl; > rcu_assign_pointer(*nl, n); > return 0; > } > > think (but are not 100% sure yet) that as a result of this error, dom0 is > not creating a cpufreq /sys interface (i.e > > Do you happen to know what may be going on? perhaps I am just misreading > the code? or perhaps not disabling PROCESSOR_EXTERNAL_CONTROL is what is > causing this behavior? I will run some experiments on this last thing today. > > Thanks again, > > Alberto > > >> Thanks, >> Kevin >> >> ------------------------------ >> *From:* xen-users-bounces@lists.xensource.com [mailto: >> xen-users-bounces@lists.xensource.com] *On Behalf Of *Alberto Munoz >> *Sent:* Thursday, November 20, 2008 2:50 AM >> *To:* xen-users@lists.xensource.com >> *Subject:* [Xen-users] Setting CPU (core) frequency from dom0 >> >> Hello everyone, >> >> I am running some experiments that require changing the frequency of a CPU >> in a SunFire machine (32-core quad socket AMD Barcelona). >> >> For what I have found (bits and pieces but not a comprehensive >> description), there are two meachisms for controlling core (most probably >> socket) frequency in Xen: >> >> A- The older (xen-3.2.1) mechnism through dom0 (option >> cpufreq=dom0-kernel), which for what I gather uses a module in dom0 >> (cpufreqd?) that allows one to set cpu frequency. >> >> B- The newer (xen-3.3), which has moved the governor to the hypervisor >> (option cpufreq=xen), which other than a utility to read processor P and C >> states (xenpm) does not (yet) allow user (dom0) control of CPU frequency. >> >> My first question is whetherot what I have written above is accurate. My >> second question is where can I find detailed information on how to set up my >> system to make use of A above and be able to set cpu frequency "manually" >> from Dom0 (assuming that is still possible in Xen 3.3). >> >> I am running the latest testing version of Xen 3.3 (about a week old). >> >> Any information would be greatly appreciated. >> >> Thank you, >> >> Alberto >> >> >> _______________________________________________ >> Xen-users mailing list >> Xen-users@lists.xensource.com >> http://lists.xensource.com/xen-users >> > >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Alberto Munoz
2008-Nov-22 00:23 UTC
Re: [Xen-users] Setting CPU (core) frequency from dom0
I did some additional poking around and figure out that the failure I am
experiencing (no sysfs interface for cpufreq) is because the call to
powernow_k8_cpu_init_acpi() in powernowk8_cpu_init() is failing (returning a
value != 0) and I have more than 1 CPU. When I enabled debugging, the system
printed the following error:
*powernow-k8: Found 32 Quad-Core AMD Opteron(tm) Processor 8356 processors
(version 2.20.00)*
*cpufreq-core: trying to register driver powernow-k8*
*cpufreq-core: adding CPU 0*
*powernow-k8: Your BIOS does not provide _PSS objects. PowerNow! does not
work on SMP systems without _PSS objects. Complain to your BIOS vendor.*
*cpufreq-core: initialization failed*
*cpufreq-core: adding CPU 1*
*powernow-k8: Your BIOS does not provide _PSS objects. PowerNow! does not
work on SMP systems without _PSS objects. Complain to your BIOS vendor.*
*cpufreq-core: initialization failed
.
.
.
*
*
*And continues to print this for all 32 cores. After this it prints the
following message:
*cpufreq-core: initialization failed*
*cpufreq-core: no CPU initialized for driver powernow-k8*
*cpufreq-core: unregistering CPU 0*
*cpufreq-core: unregistering CPU 1
.
.
.
cpufreq-core: unregistering CPU 31
*
**
The code gets a bit cryptic, but it seems to me that the failure may be due
to the code not properly recognizing my Barcelona
processors.check_supported_cpu() is probably failing to set cpu_family to
CPU_HW_PSTATE, although I have not yet confirmed that this is the case.
Have you seen this type of problem recently?
Thank you,
Alberto
On Fri, Nov 21, 2008 at 8:47 AM, Alberto Munoz <ajmunoz@google.com> wrote:
> Hi Kevin,
>
> On Thu, Nov 20, 2008 at 7:02 PM, Tian, Kevin <kevin.tian@intel.com>
wrote:
>
>> ETA can be in one or two weeks, and now coding is close to end (by
>> Jinsong). This patch sets will cover many control bits besides allowing
user
>> to change freq as I said earlier.
>>
>
> Excellent! How do I find out when the patch has been made available?
>
>
>>
>> For the code you mentioned, it''s one bug since as you cited
that return-0
>> means success. However it looks that this warning doesn''t hurt
the behavior:
>> if (!cpufreq_register_notifier(&time_cpufreq_notifier_block,
>> CPUFREQ_TRANSITION_NOTIFIER)) {
>> printk(KERN_ERR "failed to set up cpufreq
notifier\n");
>> return -ENODEV;
>> }
>> return 0;
>>
>> Notifier is registered successfully and there''s no code to
reverse the
>> effect even when -ENODEV is returned. :-)
>>
>
> Yes, I figured that out yesterday. Other than printing the error, the
> system does nothing with the -ENODEV return. Still, I am not getting a
sysfs
> interface for cpufreq and I haven''t been able to figure out why.
>
>
>> BTW in xen3.2, there''s no PROCESSOR_EXTERNAL_CONTROL.
>>
>
> In case this was not clear, I am trying to use method A
> (cpufreq=dom0-kernel) with Xen 3.3 (not 3.2). Does that not work in Xen
3.3?
>
> Also, do you happen to know of a place where I can get a list of what needs
> to be set up in order to get this frequency scaling to work. I am pretty
> sure that my problem with not getting the sysfs interface for cpufreq (it
is
> available for other things) is related to something I am missing in the
> configuration. So far, what I have done (for method A) is:
>
> - Set the option cpufreq=dom0-kernel as an option to the Xen hypervisor (in
> grub)
>
> - Disable PROCESSOR_EXTERNAL_CONTROL in drivers/acpi/Kconfig (for dom0)
>
> - Enable CONFIG_CPU_FREQ for dom0 (I did this from arch/x86_64/Kconfig)
>
> Perhaps there is a BIOS setting for the CPU that I am unaware of (my
> machine is using Barcelona CPUs)?
>
> Thank you,
>
> Alberto
>
>>
>> Thanks,
>> Kevin
>>
>> ------------------------------
>> *From:* xen-users-bounces@lists.xensource.com [mailto:
>> xen-users-bounces@lists.xensource.com] *On Behalf Of *Alberto Munoz
>> *Sent:* Friday, November 21, 2008 2:39 AM
>> *To:* Tian, Kevin
>> *Cc:* bmunoz@acm.org; xen-users@lists.xensource.com
>> *Subject:* Re: [Xen-users] Setting CPU (core) frequency from dom0
>>
>> Hi Kevin,
>>
>> Thank you very much for the reply.
>>
>> PLease see comments below.
>>
>> Alberto
>>
>> On Wed, Nov 19, 2008 at 7:05 PM, Tian, Kevin
<kevin.tian@intel.com>wrote:
>>
>>> Your description is basically correct. Do you want to control cpu
>>> frequency from dom0 user level, or just try cpufreq governor in
dom0?
>>>
>>
>> I would like to control frequency from dom0. I want to arbitrarily set
>> the CPU frequency to a value and have it stay there (regardless of
the
>> load on that CPU) until I change it.
>>
>> For the former, we''re currently adding more flexibility to
xen cpufreq
>>> (such as user space governor) and control options to xenpm (such as
manually
>>> changing freq), which is expected to reach xen upstream soon.
>>>
>>
>> Yes, I thik this is what I need (ability to manually change frequency).
Do
>> you have an ETA (estimated time of arrival) for that functionality?
>>
>>
>>> For the latter, it''s suboptimal with limitations which is
why xen
>>> cpufreq is develeoped. You may manually disable
PROCESSOR_EXTERNAL_CONTROL
>>> in drivers/acpi/Kconfig to rebuild dom0 kernel for mode A.
>>>
>>
>> OK. I will do that.
>>
>> By the way, I have been running onto an error when booting (in mode
A).
>> The function cpufreq_time_setup() in
>> linux-2.6.18-xen.hg/arch/i386/kernel/time-xen.c is printing the
following
>> message during boot (and returning -ENODEV to its caller):
>>
>> *failed to set up cpufreq notifier*
>>
>> Further examination of the code shows that this happens when
>> notifier_chain_register() in linux-2.6.18-xen.hg/kernel/sys.c returns
0. The
>> problem is that in the code I have, that function ALWAYS returns 0. The
code
>> for that function is as follows:
>>
>> static int notifier_chain_register(struct notifier_block **nl,
>> struct notifier_block *n)
>> {
>> while ((*nl) != NULL) {
>> if (n->priority > (*nl)->priority)
>> break;
>> nl = &((*nl)->next);
>> }
>> n->next = *nl;
>> rcu_assign_pointer(*nl, n);
>> return 0;
>> }
>>
>> think (but are not 100% sure yet) that as a result of this error, dom0
is
>> not creating a cpufreq /sys interface (i.e
>>
>> Do you happen to know what may be going on? perhaps I am just
misreading
>> the code? or perhaps not disabling PROCESSOR_EXTERNAL_CONTROL is what
is
>> causing this behavior? I will run some experiments on this last thing
today.
>>
>> Thanks again,
>>
>> Alberto
>>
>>
>>> Thanks,
>>> Kevin
>>>
>>> ------------------------------
>>> *From:* xen-users-bounces@lists.xensource.com [mailto:
>>> xen-users-bounces@lists.xensource.com] *On Behalf Of *Alberto Munoz
>>> *Sent:* Thursday, November 20, 2008 2:50 AM
>>> *To:* xen-users@lists.xensource.com
>>> *Subject:* [Xen-users] Setting CPU (core) frequency from dom0
>>>
>>> Hello everyone,
>>>
>>> I am running some experiments that require changing the frequency
of a
>>> CPU in a SunFire machine (32-core quad socket AMD Barcelona).
>>>
>>> For what I have found (bits and pieces but not a comprehensive
>>> description), there are two meachisms for controlling core (most
probably
>>> socket) frequency in Xen:
>>>
>>> A- The older (xen-3.2.1) mechnism through dom0 (option
>>> cpufreq=dom0-kernel), which for what I gather uses a module in dom0
>>> (cpufreqd?) that allows one to set cpu frequency.
>>>
>>> B- The newer (xen-3.3), which has moved the governor to the
hypervisor
>>> (option cpufreq=xen), which other than a utility to read processor
P and C
>>> states (xenpm) does not (yet) allow user (dom0) control of CPU
frequency.
>>>
>>> My first question is whetherot what I have written above is
accurate. My
>>> second question is where can I find detailed information on how to
set up my
>>> system to make use of A above and be able to set cpu frequency
"manually"
>>> from Dom0 (assuming that is still possible in Xen 3.3).
>>>
>>> I am running the latest testing version of Xen 3.3 (about a week
old).
>>>
>>> Any information would be greatly appreciated.
>>>
>>> Thank you,
>>>
>>> Alberto
>>>
>>>
>>> _______________________________________________
>>> Xen-users mailing list
>>> Xen-users@lists.xensource.com
>>> http://lists.xensource.com/xen-users
>>>
>>
>>
>
_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users
No, at least for all Intel platforms I''ve tried by far. Maybe AMD
people can better answer your question. One suggestion to you is to try native
linux first (both latest version and 2.6.18 as dom0 is based on 2.6.18).
It''s possible that dom0 fails to catch up some newer linux fix or your
BIOS setting is incorrect. Or if possible you can also try Intel platform to see
whether same thing also happens.
Thanks,
Kevin
________________________________
From: ajmunoz@google.com [mailto:ajmunoz@google.com] On Behalf Of Alberto Munoz
Sent: Saturday, November 22, 2008 8:23 AM
To: Tian, Kevin
Cc: bmunoz@acm.org; xen-users@lists.xensource.com; Liu, Jinsong
Subject: Re: [Xen-users] Setting CPU (core) frequency from dom0
I did some additional poking around and figure out that the failure I am
experiencing (no sysfs interface for cpufreq) is because the call to
powernow_k8_cpu_init_acpi() in powernowk8_cpu_init() is failing (returning a
value != 0) and I have more than 1 CPU. When I enabled debugging, the system
printed the following error:
powernow-k8: Found 32 Quad-Core AMD Opteron(tm) Processor 8356 processors
(version 2.20.00)
cpufreq-core: trying to register driver powernow-k8
cpufreq-core: adding CPU 0
powernow-k8: Your BIOS does not provide _PSS objects. PowerNow! does not work
on SMP systems without _PSS objects. Complain to your BIOS vendor.
cpufreq-core: initialization failed
cpufreq-core: adding CPU 1
powernow-k8: Your BIOS does not provide _PSS objects. PowerNow! does not work
on SMP systems without _PSS objects. Complain to your BIOS vendor.
cpufreq-core: initialization failed
.
.
.
And continues to print this for all 32 cores. After this it prints the following
message:
cpufreq-core: initialization failed
cpufreq-core: no CPU initialized for driver powernow-k8
cpufreq-core: unregistering CPU 0
cpufreq-core: unregistering CPU 1
.
.
.
cpufreq-core: unregistering CPU 31
The code gets a bit cryptic, but it seems to me that the failure may be due to
the code not properly recognizing my Barcelona processors.check_supported_cpu()
is probably failing to set cpu_family to CPU_HW_PSTATE, although I have not yet
confirmed that this is the case.
Have you seen this type of problem recently?
Thank you,
Alberto
On Fri, Nov 21, 2008 at 8:47 AM, Alberto Munoz
<ajmunoz@google.com<mailto:ajmunoz@google.com>> wrote:
Hi Kevin,
On Thu, Nov 20, 2008 at 7:02 PM, Tian, Kevin
<kevin.tian@intel.com<mailto:kevin.tian@intel.com>> wrote:
ETA can be in one or two weeks, and now coding is close to end (by Jinsong).
This patch sets will cover many control bits besides allowing user to change
freq as I said earlier.
Excellent! How do I find out when the patch has been made available?
For the code you mentioned, it''s one bug since as you cited that
return-0 means success. However it looks that this warning doesn''t hurt
the behavior:
if (!cpufreq_register_notifier(&time_cpufreq_notifier_block,
CPUFREQ_TRANSITION_NOTIFIER)) {
printk(KERN_ERR "failed to set up cpufreq
notifier\n");
return -ENODEV;
}
return 0;
Notifier is registered successfully and there''s no code to reverse the
effect even when -ENODEV is returned. :-)
Yes, I figured that out yesterday. Other than printing the error, the system
does nothing with the -ENODEV return. Still, I am not getting a sysfs interface
for cpufreq and I haven''t been able to figure out why.
BTW in xen3.2, there''s no PROCESSOR_EXTERNAL_CONTROL.
In case this was not clear, I am trying to use method A (cpufreq=dom0-kernel)
with Xen 3.3 (not 3.2). Does that not work in Xen 3.3?
Also, do you happen to know of a place where I can get a list of what needs to
be set up in order to get this frequency scaling to work. I am pretty sure that
my problem with not getting the sysfs interface for cpufreq (it is available for
other things) is related to something I am missing in the configuration. So far,
what I have done (for method A) is:
- Set the option cpufreq=dom0-kernel as an option to the Xen hypervisor (in
grub)
- Disable PROCESSOR_EXTERNAL_CONTROL in drivers/acpi/Kconfig (for dom0)
- Enable CONFIG_CPU_FREQ for dom0 (I did this from arch/x86_64/Kconfig)
Perhaps there is a BIOS setting for the CPU that I am unaware of (my machine is
using Barcelona CPUs)?
Thank you,
Alberto
Thanks,
Kevin
________________________________
From:
xen-users-bounces@lists.xensource.com<mailto:xen-users-bounces@lists.xensource.com>
[mailto:xen-users-bounces@lists.xensource.com<mailto:xen-users-bounces@lists.xensource.com>]
On Behalf Of Alberto Munoz
Sent: Friday, November 21, 2008 2:39 AM
To: Tian, Kevin
Cc: bmunoz@acm.org<mailto:bmunoz@acm.org>;
xen-users@lists.xensource.com<mailto:xen-users@lists.xensource.com>
Subject: Re: [Xen-users] Setting CPU (core) frequency from dom0
Hi Kevin,
Thank you very much for the reply.
PLease see comments below.
Alberto
On Wed, Nov 19, 2008 at 7:05 PM, Tian, Kevin
<kevin.tian@intel.com<mailto:kevin.tian@intel.com>> wrote:
Your description is basically correct. Do you want to control cpu frequency from
dom0 user level, or just try cpufreq governor in dom0?
I would like to control frequency from dom0. I want to arbitrarily set the CPU
frequency to a value and have it stay there (regardless of the load on that
CPU) until I change it.
For the former, we''re currently adding more flexibility to xen cpufreq
(such as user space governor) and control options to xenpm (such as manually
changing freq), which is expected to reach xen upstream soon.
Yes, I thik this is what I need (ability to manually change frequency). Do you
have an ETA (estimated time of arrival) for that functionality?
For the latter, it''s suboptimal with limitations which is why xen
cpufreq is develeoped. You may manually disable PROCESSOR_EXTERNAL_CONTROL in
drivers/acpi/Kconfig to rebuild dom0 kernel for mode A.
OK. I will do that.
By the way, I have been running onto an error when booting (in mode A). The
function cpufreq_time_setup() in
linux-2.6.18-xen.hg/arch/i386/kernel/time-xen.c is printing the following
message during boot (and returning -ENODEV to its caller):
failed to set up cpufreq notifier
Further examination of the code shows that this happens when
notifier_chain_register() in linux-2.6.18-xen.hg/kernel/sys.c returns 0. The
problem is that in the code I have, that function ALWAYS returns 0. The code for
that function is as follows:
static int notifier_chain_register(struct notifier_block **nl,
struct notifier_block *n)
{
while ((*nl) != NULL) {
if (n->priority > (*nl)->priority)
break;
nl = &((*nl)->next);
}
n->next = *nl;
rcu_assign_pointer(*nl, n);
return 0;
}
think (but are not 100% sure yet) that as a result of this error, dom0 is not
creating a cpufreq /sys interface (i.e
Do you happen to know what may be going on? perhaps I am just misreading the
code? or perhaps not disabling PROCESSOR_EXTERNAL_CONTROL is what is causing
this behavior? I will run some experiments on this last thing today.
Thanks again,
Alberto
Thanks,
Kevin
________________________________
From:
xen-users-bounces@lists.xensource.com<mailto:xen-users-bounces@lists.xensource.com>
[mailto:xen-users-bounces@lists.xensource.com<mailto:xen-users-bounces@lists.xensource.com>]
On Behalf Of Alberto Munoz
Sent: Thursday, November 20, 2008 2:50 AM
To: xen-users@lists.xensource.com<mailto:xen-users@lists.xensource.com>
Subject: [Xen-users] Setting CPU (core) frequency from dom0
Hello everyone,
I am running some experiments that require changing the frequency of a CPU in a
SunFire machine (32-core quad socket AMD Barcelona).
For what I have found (bits and pieces but not a comprehensive description),
there are two meachisms for controlling core (most probably socket) frequency in
Xen:
A- The older (xen-3.2.1) mechnism through dom0 (option cpufreq=dom0-kernel),
which for what I gather uses a module in dom0 (cpufreqd?) that allows one to set
cpu frequency.
B- The newer (xen-3.3), which has moved the governor to the hypervisor (option
cpufreq=xen), which other than a utility to read processor P and C states
(xenpm) does not (yet) allow user (dom0) control of CPU frequency.
My first question is whetherot what I have written above is accurate. My second
question is where can I find detailed information on how to set up my system to
make use of A above and be able to set cpu frequency "manually" from
Dom0 (assuming that is still possible in Xen 3.3).
I am running the latest testing version of Xen 3.3 (about a week old).
Any information would be greatly appreciated.
Thank you,
Alberto
_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com<mailto:Xen-users@lists.xensource.com>
http://lists.xensource.com/xen-users
_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users
We can copy you in the CC list when submitting patches.
We didn''t try mode A on 3.3, since we don''t think it right
thing to do. But from what you have done, it looks enough. :-)
Thanks,
Kevin
________________________________
From: Alberto Munoz [mailto:ajmunoz@google.com]
Sent: Saturday, November 22, 2008 12:47 AM
To: Tian, Kevin
Cc: bmunoz@acm.org; xen-users@lists.xensource.com; Liu, Jinsong
Subject: Re: [Xen-users] Setting CPU (core) frequency from dom0
Hi Kevin,
On Thu, Nov 20, 2008 at 7:02 PM, Tian, Kevin
<kevin.tian@intel.com<mailto:kevin.tian@intel.com>> wrote:
ETA can be in one or two weeks, and now coding is close to end (by Jinsong).
This patch sets will cover many control bits besides allowing user to change
freq as I said earlier.
Excellent! How do I find out when the patch has been made available?
For the code you mentioned, it''s one bug since as you cited that
return-0 means success. However it looks that this warning doesn''t hurt
the behavior:
if (!cpufreq_register_notifier(&time_cpufreq_notifier_block,
CPUFREQ_TRANSITION_NOTIFIER)) {
printk(KERN_ERR "failed to set up cpufreq
notifier\n");
return -ENODEV;
}
return 0;
Notifier is registered successfully and there''s no code to reverse the
effect even when -ENODEV is returned. :-)
Yes, I figured that out yesterday. Other than printing the error, the system
does nothing with the -ENODEV return. Still, I am not getting a sysfs interface
for cpufreq and I haven''t been able to figure out why.
BTW in xen3.2, there''s no PROCESSOR_EXTERNAL_CONTROL.
In case this was not clear, I am trying to use method A (cpufreq=dom0-kernel)
with Xen 3.3 (not 3.2). Does that not work in Xen 3.3?
Also, do you happen to know of a place where I can get a list of what needs to
be set up in order to get this frequency scaling to work. I am pretty sure that
my problem with not getting the sysfs interface for cpufreq (it is available for
other things) is related to something I am missing in the configuration. So far,
what I have done (for method A) is:
- Set the option cpufreq=dom0-kernel as an option to the Xen hypervisor (in
grub)
- Disable PROCESSOR_EXTERNAL_CONTROL in drivers/acpi/Kconfig (for dom0)
- Enable CONFIG_CPU_FREQ for dom0 (I did this from arch/x86_64/Kconfig)
Perhaps there is a BIOS setting for the CPU that I am unaware of (my machine is
using Barcelona CPUs)?
Thank you,
Alberto
Thanks,
Kevin
________________________________
From:
xen-users-bounces@lists.xensource.com<mailto:xen-users-bounces@lists.xensource.com>
[mailto:xen-users-bounces@lists.xensource.com<mailto:xen-users-bounces@lists.xensource.com>]
On Behalf Of Alberto Munoz
Sent: Friday, November 21, 2008 2:39 AM
To: Tian, Kevin
Cc: bmunoz@acm.org<mailto:bmunoz@acm.org>;
xen-users@lists.xensource.com<mailto:xen-users@lists.xensource.com>
Subject: Re: [Xen-users] Setting CPU (core) frequency from dom0
Hi Kevin,
Thank you very much for the reply.
PLease see comments below.
Alberto
On Wed, Nov 19, 2008 at 7:05 PM, Tian, Kevin
<kevin.tian@intel.com<mailto:kevin.tian@intel.com>> wrote:
Your description is basically correct. Do you want to control cpu frequency from
dom0 user level, or just try cpufreq governor in dom0?
I would like to control frequency from dom0. I want to arbitrarily set the CPU
frequency to a value and have it stay there (regardless of the load on that
CPU) until I change it.
For the former, we''re currently adding more flexibility to xen cpufreq
(such as user space governor) and control options to xenpm (such as manually
changing freq), which is expected to reach xen upstream soon.
Yes, I thik this is what I need (ability to manually change frequency). Do you
have an ETA (estimated time of arrival) for that functionality?
For the latter, it''s suboptimal with limitations which is why xen
cpufreq is develeoped. You may manually disable PROCESSOR_EXTERNAL_CONTROL in
drivers/acpi/Kconfig to rebuild dom0 kernel for mode A.
OK. I will do that.
By the way, I have been running onto an error when booting (in mode A). The
function cpufreq_time_setup() in
linux-2.6.18-xen.hg/arch/i386/kernel/time-xen.c is printing the following
message during boot (and returning -ENODEV to its caller):
failed to set up cpufreq notifier
Further examination of the code shows that this happens when
notifier_chain_register() in linux-2.6.18-xen.hg/kernel/sys.c returns 0. The
problem is that in the code I have, that function ALWAYS returns 0. The code for
that function is as follows:
static int notifier_chain_register(struct notifier_block **nl,
struct notifier_block *n)
{
while ((*nl) != NULL) {
if (n->priority > (*nl)->priority)
break;
nl = &((*nl)->next);
}
n->next = *nl;
rcu_assign_pointer(*nl, n);
return 0;
}
think (but are not 100% sure yet) that as a result of this error, dom0 is not
creating a cpufreq /sys interface (i.e
Do you happen to know what may be going on? perhaps I am just misreading the
code? or perhaps not disabling PROCESSOR_EXTERNAL_CONTROL is what is causing
this behavior? I will run some experiments on this last thing today.
Thanks again,
Alberto
Thanks,
Kevin
________________________________
From:
xen-users-bounces@lists.xensource.com<mailto:xen-users-bounces@lists.xensource.com>
[mailto:xen-users-bounces@lists.xensource.com<mailto:xen-users-bounces@lists.xensource.com>]
On Behalf Of Alberto Munoz
Sent: Thursday, November 20, 2008 2:50 AM
To: xen-users@lists.xensource.com<mailto:xen-users@lists.xensource.com>
Subject: [Xen-users] Setting CPU (core) frequency from dom0
Hello everyone,
I am running some experiments that require changing the frequency of a CPU in a
SunFire machine (32-core quad socket AMD Barcelona).
For what I have found (bits and pieces but not a comprehensive description),
there are two meachisms for controlling core (most probably socket) frequency in
Xen:
A- The older (xen-3.2.1) mechnism through dom0 (option cpufreq=dom0-kernel),
which for what I gather uses a module in dom0 (cpufreqd?) that allows one to set
cpu frequency.
B- The newer (xen-3.3), which has moved the governor to the hypervisor (option
cpufreq=xen), which other than a utility to read processor P and C states
(xenpm) does not (yet) allow user (dom0) control of CPU frequency.
My first question is whetherot what I have written above is accurate. My second
question is where can I find detailed information on how to set up my system to
make use of A above and be able to set cpu frequency "manually" from
Dom0 (assuming that is still possible in Xen 3.3).
I am running the latest testing version of Xen 3.3 (about a week old).
Any information would be greatly appreciated.
Thank you,
Alberto
_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com<mailto:Xen-users@lists.xensource.com>
http://lists.xensource.com/xen-users
_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users
Alberto Munoz
2008-Nov-25 00:30 UTC
Re: [Xen-users] Setting CPU (core) frequency from dom0
Hi Kevin, As it turns out, my problem was due to not having all of the right options set for the dom0 kernel (in the .config file). The one option that got me is CONFIG_X86_POWERNOW_K8_ACPI. As it turns out, that option, when not set, replaces a number of the functions in powernow-k8.c with stubs that return -ENODEV. Once I got that option set, everyting worked as it should. For those of you interested, here is what I did: - set cpufreq=dom0-kernel option for the kernel line in the grub menu file (/boot/grub/menu.lst for ubuntu distributions) - set option CONFIG_CPU_FREQ for the dom0 kernel (I added an entry to linux-2.6.18-xen.hg/arch/x86_64/Kconfig) - Ensure that CONFIG_ACPI_PROCESSOR is set to "y" (not "m"!) in the configuration file. In my case this option was set to "m", and that was preventing CONFIG_X86_POWERNOW_K8_ACPI from being set. - Use the sysfs interface (/sys/devices/system/cpu/cpu*/cpufreq/) to set the CPUs to the desired frequency. On Sun, Nov 23, 2008 at 9:06 PM, Tian, Kevin <kevin.tian@intel.com> wrote:> We can copy you in the CC list when submitting patches. >Yes, that would be great. Thank you.> We didn''t try mode A on 3.3, since we don''t think it right thing to do. But > from what you have done, it looks enough. :-) >Yes, I works just fine.> > Thanks, > Kevin >Thank you for all the help. Alberto> ------------------------------ > *From:* Alberto Munoz [mailto:ajmunoz@google.com] > *Sent:* Saturday, November 22, 2008 12:47 AM > *To:* Tian, Kevin > *Cc:* bmunoz@acm.org; xen-users@lists.xensource.com; Liu, Jinsong > > *Subject:* Re: [Xen-users] Setting CPU (core) frequency from dom0 > > Hi Kevin, > > On Thu, Nov 20, 2008 at 7:02 PM, Tian, Kevin <kevin.tian@intel.com> wrote: > >> ETA can be in one or two weeks, and now coding is close to end (by >> Jinsong). This patch sets will cover many control bits besides allowing user >> to change freq as I said earlier. >> > > Excellent! How do I find out when the patch has been made available? > > >> >> For the code you mentioned, it''s one bug since as you cited that return-0 >> means success. However it looks that this warning doesn''t hurt the behavior: >> if (!cpufreq_register_notifier(&time_cpufreq_notifier_block, >> CPUFREQ_TRANSITION_NOTIFIER)) { >> printk(KERN_ERR "failed to set up cpufreq notifier\n"); >> return -ENODEV; >> } >> return 0; >> >> Notifier is registered successfully and there''s no code to reverse the >> effect even when -ENODEV is returned. :-) >> > > Yes, I figured that out yesterday. Other than printing the error, the > system does nothing with the -ENODEV return. Still, I am not getting a sysfs > interface for cpufreq and I haven''t been able to figure out why. > > >> BTW in xen3.2, there''s no PROCESSOR_EXTERNAL_CONTROL. >> > > In case this was not clear, I am trying to use method A > (cpufreq=dom0-kernel) with Xen 3.3 (not 3.2). Does that not work in Xen 3.3? > > Also, do you happen to know of a place where I can get a list of what needs > to be set up in order to get this frequency scaling to work. I am pretty > sure that my problem with not getting the sysfs interface for cpufreq (it is > available for other things) is related to something I am missing in the > configuration. So far, what I have done (for method A) is: > > - Set the option cpufreq=dom0-kernel as an option to the Xen hypervisor (in > grub) > > - Disable PROCESSOR_EXTERNAL_CONTROL in drivers/acpi/Kconfig (for dom0) > > - Enable CONFIG_CPU_FREQ for dom0 (I did this from arch/x86_64/Kconfig) > > Perhaps there is a BIOS setting for the CPU that I am unaware of (my > machine is using Barcelona CPUs)? > > Thank you, > > Alberto > >> >> Thanks, >> Kevin >> >> ------------------------------ >> *From:* xen-users-bounces@lists.xensource.com [mailto: >> xen-users-bounces@lists.xensource.com] *On Behalf Of *Alberto Munoz >> *Sent:* Friday, November 21, 2008 2:39 AM >> *To:* Tian, Kevin >> *Cc:* bmunoz@acm.org; xen-users@lists.xensource.com >> *Subject:* Re: [Xen-users] Setting CPU (core) frequency from dom0 >> >> Hi Kevin, >> >> Thank you very much for the reply. >> >> PLease see comments below. >> >> Alberto >> >> On Wed, Nov 19, 2008 at 7:05 PM, Tian, Kevin <kevin.tian@intel.com>wrote: >> >>> Your description is basically correct. Do you want to control cpu >>> frequency from dom0 user level, or just try cpufreq governor in dom0? >>> >> >> I would like to control frequency from dom0. I want to arbitrarily set >> the CPU frequency to a value and have it stay there (regardless of the >> load on that CPU) until I change it. >> >> For the former, we''re currently adding more flexibility to xen cpufreq >>> (such as user space governor) and control options to xenpm (such as manually >>> changing freq), which is expected to reach xen upstream soon. >>> >> >> Yes, I thik this is what I need (ability to manually change frequency). Do >> you have an ETA (estimated time of arrival) for that functionality? >> >> >>> For the latter, it''s suboptimal with limitations which is why xen >>> cpufreq is develeoped. You may manually disable PROCESSOR_EXTERNAL_CONTROL >>> in drivers/acpi/Kconfig to rebuild dom0 kernel for mode A. >>> >> >> OK. I will do that. >> >> By the way, I have been running onto an error when booting (in mode A). >> The function cpufreq_time_setup() in >> linux-2.6.18-xen.hg/arch/i386/kernel/time-xen.c is printing the following >> message during boot (and returning -ENODEV to its caller): >> >> *failed to set up cpufreq notifier* >> >> Further examination of the code shows that this happens when >> notifier_chain_register() in linux-2.6.18-xen.hg/kernel/sys.c returns 0. The >> problem is that in the code I have, that function ALWAYS returns 0. The code >> for that function is as follows: >> >> static int notifier_chain_register(struct notifier_block **nl, >> struct notifier_block *n) >> { >> while ((*nl) != NULL) { >> if (n->priority > (*nl)->priority) >> break; >> nl = &((*nl)->next); >> } >> n->next = *nl; >> rcu_assign_pointer(*nl, n); >> return 0; >> } >> >> think (but are not 100% sure yet) that as a result of this error, dom0 is >> not creating a cpufreq /sys interface (i.e >> >> Do you happen to know what may be going on? perhaps I am just misreading >> the code? or perhaps not disabling PROCESSOR_EXTERNAL_CONTROL is what is >> causing this behavior? I will run some experiments on this last thing today. >> >> Thanks again, >> >> Alberto >> >> >>> Thanks, >>> Kevin >>> >>> ------------------------------ >>> *From:* xen-users-bounces@lists.xensource.com [mailto: >>> xen-users-bounces@lists.xensource.com] *On Behalf Of *Alberto Munoz >>> *Sent:* Thursday, November 20, 2008 2:50 AM >>> *To:* xen-users@lists.xensource.com >>> *Subject:* [Xen-users] Setting CPU (core) frequency from dom0 >>> >>> Hello everyone, >>> >>> I am running some experiments that require changing the frequency of a >>> CPU in a SunFire machine (32-core quad socket AMD Barcelona). >>> >>> For what I have found (bits and pieces but not a comprehensive >>> description), there are two meachisms for controlling core (most probably >>> socket) frequency in Xen: >>> >>> A- The older (xen-3.2.1) mechnism through dom0 (option >>> cpufreq=dom0-kernel), which for what I gather uses a module in dom0 >>> (cpufreqd?) that allows one to set cpu frequency. >>> >>> B- The newer (xen-3.3), which has moved the governor to the hypervisor >>> (option cpufreq=xen), which other than a utility to read processor P and C >>> states (xenpm) does not (yet) allow user (dom0) control of CPU frequency. >>> >>> My first question is whetherot what I have written above is accurate. My >>> second question is where can I find detailed information on how to set up my >>> system to make use of A above and be able to set cpu frequency "manually" >>> from Dom0 (assuming that is still possible in Xen 3.3). >>> >>> I am running the latest testing version of Xen 3.3 (about a week old). >>> >>> Any information would be greatly appreciated. >>> >>> Thank you, >>> >>> Alberto >>> >>> >>> _______________________________________________ >>> Xen-users mailing list >>> Xen-users@lists.xensource.com >>> http://lists.xensource.com/xen-users >>> >> >> >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users