Re: [Xen-devel] [RFC PATCH 04/31] cpufreq: make turbo settings to be configurable

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 18.05.18 at 16:36, <olekstysh@xxxxxxxxx> wrote:
> BTW, what do you think about the following:
> 
> Another question is second_max_freq. As I understand, it is highest
> non-turbo frequency calculated by framework to limit target frequency
> when turbo mode "is disabled". And Xen assumes that second_max_freq is
> always P1 if turbo mode is on.
> But, there might be a case when a few highest frequencies are
> turbo-frequencies. So, I propose to add an extra flag for handling
> that. So, each CPUFreq driver responsibility will be to mark
> turbo-frequency(ies) for the framework to properly calculate
> second_max_freq.

Sounds reasonable at the first glance.

Jan

> Something like that:
> 
> diff --git a/xen/drivers/cpufreq/utility.c b/xen/drivers/cpufreq/utility.c
> index 25bf983..122a88b 100644
> --- a/xen/drivers/cpufreq/utility.c
> +++ b/xen/drivers/cpufreq/utility.c
> @@ -226,7 +226,8 @@ int cpufreq_frequency_table_cpuinfo(struct
> cpufreq_policy *policy,
>  #ifdef CONFIG_HAS_CPU_TURBO
>      for (i=0; (table[i].frequency != CPUFREQ_TABLE_END); i++) {
>          unsigned int freq = table[i].frequency;
> -        if (freq == CPUFREQ_ENTRY_INVALID || freq == max_freq)
> +        if ((freq == CPUFREQ_ENTRY_INVALID) ||
> +            (table[i].flags & CPUFREQ_BOOST_FREQ))
>              continue;
>          if (freq > second_max_freq)
>              second_max_freq = freq;
> diff --git a/xen/include/xen/cpufreq.h b/xen/include/xen/cpufreq.h
> index 2e0c16a..77b29da 100644
> --- a/xen/include/xen/cpufreq.h
> +++ b/xen/include/xen/cpufreq.h
> @@ -204,7 +204,11 @@ void cpufreq_verify_within_limits(struct
> cpufreq_policy *policy,
>  #define CPUFREQ_ENTRY_INVALID ~0
>  #define CPUFREQ_TABLE_END     ~1
> 
> +/* Special Values of .flags field */
> +#define CPUFREQ_BOOST_FREQ    (1 << 0)
> +
>  struct cpufreq_frequency_table {
> +       unsigned int    flags;
>      unsigned int    index;     /* any */
>      unsigned int    frequency; /* kHz - doesn't need to be in ascending
>                                  * order */
> 
> Both existing on x86 CPUFreq drivers just need to mark P0 frequency as
> a turbo-frequency if turbo mode "is supported".
> 
>>
>> Jan
>>
>>
> 
> -- 
> Regards,
> 
> Oleksandr Tyshchenko





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