Re: [patch 03/10] x86/aperfmperf: Separate AP/BP frequency invariance init

Rafael J. Wysocki
2022-04-19T16:04:22Z

On Fri, Apr 15, 2022 at 9:19 PM Thomas Gleixner <tglx@linutronix.de> wrote:
>
> This code is convoluted and because it can be invoked post init via the
> ACPI/CPPC code, all of the initialization functionality is built in instead
> of being part of init text and init data.
>
> As a first step create separate calls for the boot and the application
> processors.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> arch/x86/include/asm/topology.h | 12 +++++-------
> arch/x86/kernel/acpi/cppc.c | 3 ++-
> arch/x86/kernel/cpu/aperfmperf.c | 23 +++++++++++------------
> arch/x86/kernel/smpboot.c | 4 ++--
> 4 files changed, 20 insertions(+), 22 deletions(-)
>
> --- a/arch/x86/include/asm/topology.h
> +++ b/arch/x86/include/asm/topology.h
> @@ -216,14 +216,12 @@ extern void arch_scale_freq_tick(void);
> #define arch_scale_freq_tick arch_scale_freq_tick
>
> extern void arch_set_max_freq_ratio(bool turbo_disabled);
> -void init_freq_invariance(bool secondary, bool cppc_ready);
> +extern void bp_init_freq_invariance(bool cppc_ready);
> +extern void ap_init_freq_invariance(void);
> #else
> -static inline void arch_set_max_freq_ratio(bool turbo_disabled)
> -{
> -}
> -static inline void init_freq_invariance(bool secondary, bool cppc_ready)
> -{
> -}
> +static inline void arch_set_max_freq_ratio(bool turbo_disabled) { }
> +static inline void bp_init_freq_invariance(bool cppc_ready) { }
> +static inline void ap_init_freq_invariance(void) { }
> #endif
>
> #ifdef CONFIG_ACPI_CPPC_LIB
> --- a/arch/x86/kernel/acpi/cppc.c
> +++ b/arch/x86/kernel/acpi/cppc.c
> @@ -96,7 +96,8 @@ void init_freq_invariance_cppc(void)
>
> mutex_lock(&freq_invariance_lock);
>
> - init_freq_invariance(secondary, true);
> + if (!secondary)
> + bp_init_freq_invariance(true);
> secondary = true;
>
> mutex_unlock(&freq_invariance_lock);
> --- a/arch/x86/kernel/cpu/aperfmperf.c
> +++ b/arch/x86/kernel/cpu/aperfmperf.c
> @@ -428,31 +428,24 @@ static void register_freq_invariance_sys
> static inline void register_freq_invariance_syscore_ops(void) {}
> #endif
>
> -void init_freq_invariance(bool secondary, bool cppc_ready)
> +void bp_init_freq_invariance(bool cppc_ready)
> {
> - bool ret = false;
> + bool ret;
>
> - if (!boot_cpu_has(X86_FEATURE_APERFMPERF))
> + if (!cpu_feature_enabled(X86_FEATURE_APERFMPERF))
> return;
>
> - if (secondary) {
> - if (static_branch_likely(&arch_scale_freq_key)) {
> - init_counter_refs();
> - }
> - return;
> - }
> + init_counter_refs();
>
> if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
> ret = intel_set_max_freq_ratio();
> else if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
> - if (!cppc_ready) {
> + if (!cppc_ready)
> return;
> - }
> ret = amd_set_max_freq_ratio(&arch_turbo_freq_ratio);
> }
>
> if (ret) {
> - init_counter_refs();
> static_branch_enable(&arch_scale_freq_key);
> register_freq_invariance_syscore_ops();
> pr_info("Estimated ratio of average max frequency by base frequency (times 1024): %llu\n", arch_max_freq_ratio);
> @@ -461,6 +454,12 @@ void init_freq_invariance(bool secondary
> }
> }
>
> +void ap_init_freq_invariance(void)
> +{
> + if (cpu_feature_enabled(X86_FEATURE_APERFMPERF))
> + init_counter_refs();

This doesn't check arch_scale_freq_key now which may be a good thing
to mention in the changelog.

I don't see anything questionable in the patch, though, so

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

> +}
> +
> static void disable_freq_invariance_workfn(struct work_struct *work)
> {
> static_branch_disable(&arch_scale_freq_key);
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -186,7 +186,7 @@ static void smp_callin(void)
> */
> set_cpu_sibling_map(raw_smp_processor_id());
>
> - init_freq_invariance(true, false);
> + ap_init_freq_invariance();
>
> /*
> * Get our bogomips.
> @@ -1396,7 +1396,7 @@ void __init native_smp_prepare_cpus(unsi
> {
> smp_prepare_cpus_common();
>
> - init_freq_invariance(false, false);
> + bp_init_freq_invariance(false);
> smp_sanity_check();
>
> switch (apic_intr_mode) {
>