Linda，
> 在 2014年12月6日，00:09，Linda Knippers <linda.knippers@xxxxxx> 写道：
>
>> On 12/5/2014 4:40 AM, Ethan Zhao wrote:
>> To force loading on Oracle Sun X86 servers, provide one kernel command line
>> parameter
>>
>> intel_pstate = force
>>
>> For those who be aware of the risk of no power capping capabily working and
>> try to get better performance with this driver.
>>
>> Signed-off-by: Ethan Zhao <ethan.zhao@xxxxxxxxxx>
>> Tested-by: Alexey Kodanev <alexey.kodanev@xxxxxxxxxx>
>> ---
>> v2: change to hardware vendor specific naming parameter.
>> v4: refine code and doc.
>> v5&v6: fix a typo in doc.
>> v7: change enum PCC to PPC.
>> v8: change the name of kernel command line parameter to generic one.
>>
>> Documentation/kernel-parameters.txt | 5 +++++
>> drivers/cpufreq/intel_pstate.c | 6 +++++-
>> 2 files changed, 10 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
>> index 479f332..7d0983e 100644
>> --- a/Documentation/kernel-parameters.txt
>> +++ b/Documentation/kernel-parameters.txt
>> @@ -1446,6 +1446,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>> disable
>> Do not enable intel_pstate as the default
>> scaling driver for the supported processors
>> + force
>> + Enable intel_pstate on systems where it may cause problems to
>> + happen due to conflicts with platform firmware attempting to
>> + drive P-states by itself in certain situations (for thermal
>> + control or power capping in general or other purposes).
>
> I suggest something like:
> Enable intel_pstate on systems that prohibit it by
> default in favor of acpi-cpufreq. Forcing the
> intel_pstate driver instead of acpi-cpufreq may disable
> platform features, such as thermal controls and power
> capping, that rely on ACPI p-state information being
P-States
> Used by the OS and therefore should be used with care.
Indicated to OSPM caution
> This option does not work with processors that aren't
> supported by the intel_pstate driver or on platforms
> that use pcc-cpufreq instead of acpi-cpufreq.
>
> Maybe this is too specific but I believe it is accurate. Comments?
>
Looks better to me, except some words commented.
Thanks,
Ethan
> -- ljk
>
>>
>> intremap= [X86-64, Intel-IOMMU]
>> on enable Interrupt Remapping (default)
>> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
>> index 1bb62ca..2654e13 100644
>> --- a/drivers/cpufreq/intel_pstate.c
>> +++ b/drivers/cpufreq/intel_pstate.c
>> @@ -866,6 +866,7 @@ static struct cpufreq_driver intel_pstate_driver = {
>> };
>>
>> static int __initdata no_load;
>> +static unsigned int force_load;
>>
>> static int intel_pstate_msrs_not_valid(void)
>> {
>> @@ -1003,7 +1004,8 @@ static bool intel_pstate_platform_pwr_mgmt_exists(void)
>> case PSS:
>> return intel_pstate_no_acpi_pss();
>> case PPC:
>> - return intel_pstate_has_acpi_ppc();
>> + return intel_pstate_has_acpi_ppc() &&
>> + (!force_load);
>> }
>> }
>>
>> @@ -1078,6 +1080,8 @@ static int __init intel_pstate_setup(char *str)
>>
>> if (!strcmp(str, "disable"))
>> no_load = 1;
>> + if (!strcmp(str, "force"))
>> + force_load = 1;
>> return 0;
>> }
>> early_param("intel_pstate", intel_pstate_setup);
>
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