On 22-10-20, 09:11, Peter Zijlstra wrote:
> Well, but we need to do something to force people onto schedutil,
> otherwise we'll get more crap like this thread.
>
> Can we take the choice away? Only let Kconfig select which governors are
> available and then set the default ourselves? I mean, the end goal being
> to not have selectable governors at all, this seems like a good step
> anyway.
Just to clarify and complete the point a bit here, the users can still
pass the default governor from cmdline using
cpufreq.default_governor=, which will take precedence over the one the
below code is playing with. And later once the kernel is up, they can
still choose a different governor from userspace.
> ---
>
> diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
> index 2c7171e0b001..3a9f54b382c0 100644
> --- a/drivers/cpufreq/Kconfig
> +++ b/drivers/cpufreq/Kconfig
> @@ -34,77 +34,6 @@ config CPU_FREQ_STAT
>
> If in doubt, say N.
>
> -choice
> - prompt "Default CPUFreq governor"
> - default CPU_FREQ_DEFAULT_GOV_USERSPACE if ARM_SA1100_CPUFREQ || ARM_SA1110_CPUFREQ
> - default CPU_FREQ_DEFAULT_GOV_SCHEDUTIL if ARM64 || ARM
> - default CPU_FREQ_DEFAULT_GOV_SCHEDUTIL if X86_INTEL_PSTATE && SMP
> - default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
> - help
> - This option sets which CPUFreq governor shall be loaded at
> - startup. If in doubt, use the default setting.
> -
> -config CPU_FREQ_DEFAULT_GOV_PERFORMANCE
> - bool "performance"
> - select CPU_FREQ_GOV_PERFORMANCE
> - help
> - Use the CPUFreq governor 'performance' as default. This sets
> - the frequency statically to the highest frequency supported by
> - the CPU.
> -
> -config CPU_FREQ_DEFAULT_GOV_POWERSAVE
> - bool "powersave"
> - select CPU_FREQ_GOV_POWERSAVE
> - help
> - Use the CPUFreq governor 'powersave' as default. This sets
> - the frequency statically to the lowest frequency supported by
> - the CPU.
> -
> -config CPU_FREQ_DEFAULT_GOV_USERSPACE
> - bool "userspace"
> - select CPU_FREQ_GOV_USERSPACE
> - help
> - Use the CPUFreq governor 'userspace' as default. This allows
> - you to set the CPU frequency manually or when a userspace
> - program shall be able to set the CPU dynamically without having
> - to enable the userspace governor manually.
> -
> -config CPU_FREQ_DEFAULT_GOV_ONDEMAND
> - bool "ondemand"
> - select CPU_FREQ_GOV_ONDEMAND
> - select CPU_FREQ_GOV_PERFORMANCE
> - help
> - Use the CPUFreq governor 'ondemand' as default. This allows
> - you to get a full dynamic frequency capable system by simply
> - loading your cpufreq low-level hardware driver.
> - Be aware that not all cpufreq drivers support the ondemand
> - governor. If unsure have a look at the help section of the
> - driver. Fallback governor will be the performance governor.
> -
> -config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
> - bool "conservative"
> - select CPU_FREQ_GOV_CONSERVATIVE
> - select CPU_FREQ_GOV_PERFORMANCE
> - help
> - Use the CPUFreq governor 'conservative' as default. This allows
> - you to get a full dynamic frequency capable system by simply
> - loading your cpufreq low-level hardware driver.
> - Be aware that not all cpufreq drivers support the conservative
> - governor. If unsure have a look at the help section of the
> - driver. Fallback governor will be the performance governor.
> -
> -config CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
> - bool "schedutil"
> - depends on SMP
> - select CPU_FREQ_GOV_SCHEDUTIL
> - select CPU_FREQ_GOV_PERFORMANCE
> - help
> - Use the 'schedutil' CPUFreq governor by default. If unsure,
> - have a look at the help section of that governor. The fallback
> - governor will be 'performance'.
> -
> -endchoice
> -
> config CPU_FREQ_GOV_PERFORMANCE
> tristate "'performance' governor"
> help
> @@ -145,6 +74,7 @@ config CPU_FREQ_GOV_USERSPACE
> config CPU_FREQ_GOV_ONDEMAND
> tristate "'ondemand' cpufreq policy governor"
> select CPU_FREQ_GOV_COMMON
> + select CPU_FREQ_GOV_PERFORMANCE
> help
> 'ondemand' - This driver adds a dynamic cpufreq policy governor.
> The governor does a periodic polling and
> @@ -164,6 +94,7 @@ config CPU_FREQ_GOV_CONSERVATIVE
> tristate "'conservative' cpufreq governor"
> depends on CPU_FREQ
> select CPU_FREQ_GOV_COMMON
> + select CPU_FREQ_GOV_PERFORMANCE
> help
> 'conservative' - this driver is rather similar to the 'ondemand'
> governor both in its source code and its purpose, the difference is
> @@ -188,6 +119,7 @@ config CPU_FREQ_GOV_SCHEDUTIL
> bool "'schedutil' cpufreq policy governor"
> depends on CPU_FREQ && SMP
> select CPU_FREQ_GOV_ATTR_SET
> + select CPU_FREQ_GOV_PERFORMANCE
And I am not really sure why we always wanted this backup performance
governor to be there unless the said governors are built as module.
> select IRQ_WORK
> help
> This governor makes decisions based on the utilization data provided
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 1877f5e2e5b0..6848e3337b65 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -626,6 +626,49 @@ static struct cpufreq_governor *find_governor(const char *str_governor)
> return NULL;
> }
>
> +static struct cpufreq_governor *cpufreq_default_governor(void)
> +{
> + struct cpufreq_governor *gov = NULL;
> +
> +#ifdef CONFIG_CPU_FREQ_GOV_SCHEDUTIL
> + gov = find_governor("schedutil");
> + if (gov)
> + return gov;
> +#endif
> +
> +#ifdef CONFIG_CPU_FREQ_GOV_ONDEMAND
> + gov = find_governor("ondemand");
> + if (gov)
> + return gov;
> +#endif
> +
> +#ifdef CONFIG_CPU_FREQ_GOV_CONSERVATIVE
> + gov = find_governor("conservative");
> + if (gov)
> + return gov;
> +#endif
> +
> +#ifdef CONFIG_CPU_FREQ_GOV_USERSPACE
> + gov = find_governor("userspace");
> + if (gov)
> + return gov;
> +#endif
> +
> +#ifdef CONFIG_CPU_FREQ_GOV_POWERSAVE
> + gov = find_governor("powersave");
> + if (gov)
> + return gov;
> +#endif
> +
> +#ifdef CONFIG_CPU_FREQ_GOV_PERFORMANCE
> + gov = find_governor("performance");
> + if (gov)
> + return gov;
> +#endif
> +
> + return gov;
> +}
I think that would be fine with me. Though we would be required to
update couple of defconfigs here to make sure they keep working the
way they wanted to.
--
viresh
