Re: [patch 05/10] x86/aperfmperf: Put frequency invariance aperf/mperf data into a struct

Rafael J. Wysocki
2022-04-19T16:16:12Z

On Fri, Apr 15, 2022 at 9:19 PM Thomas Gleixner <tglx@linutronix.de> wrote:
>
> Preparation for sharing code with the CPU frequency portion of the
> aperf/mperf code.
>
> No functional change.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

All good AFAICS:

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

> ---
> arch/x86/kernel/cpu/aperfmperf.c | 26 +++++++++++++++-----------
> 1 file changed, 15 insertions(+), 11 deletions(-)
>
> --- a/arch/x86/kernel/cpu/aperfmperf.c
> +++ b/arch/x86/kernel/cpu/aperfmperf.c
> @@ -22,6 +22,13 @@
>
> #include "cpu.h"
>
> +struct aperfmperf {
> + u64 aperf;
> + u64 mperf;
> +};
> +
> +static DEFINE_PER_CPU_SHARED_ALIGNED(struct aperfmperf, cpu_samples);
> +
> struct aperfmperf_sample {
> unsigned int khz;
> atomic_t scfpending;
> @@ -194,8 +201,6 @@ unsigned int arch_freq_get_on_cpu(int cp
>
> DEFINE_STATIC_KEY_FALSE(arch_scale_freq_key);
>
> -static DEFINE_PER_CPU(u64, arch_prev_aperf);
> -static DEFINE_PER_CPU(u64, arch_prev_mperf);
> static u64 arch_turbo_freq_ratio = SCHED_CAPACITY_SCALE;
> static u64 arch_max_freq_ratio = SCHED_CAPACITY_SCALE;
>
> @@ -407,8 +412,8 @@ static void init_counter_refs(void)
> rdmsrl(MSR_IA32_APERF, aperf);
> rdmsrl(MSR_IA32_MPERF, mperf);
>
> - this_cpu_write(arch_prev_aperf, aperf);
> - this_cpu_write(arch_prev_mperf, mperf);
> + this_cpu_write(cpu_samples.aperf, aperf);
> + this_cpu_write(cpu_samples.mperf, mperf);
> }
>
> #ifdef CONFIG_PM_SLEEP
> @@ -474,9 +479,8 @@ DEFINE_PER_CPU(unsigned long, arch_freq_
>
> void arch_scale_freq_tick(void)
> {
> - u64 freq_scale;
> - u64 aperf, mperf;
> - u64 acnt, mcnt;
> + struct aperfmperf *s = this_cpu_ptr(&cpu_samples);
> + u64 aperf, mperf, acnt, mcnt, freq_scale;
>
> if (!arch_scale_freq_invariant())
> return;
> @@ -484,11 +488,11 @@ void arch_scale_freq_tick(void)
> rdmsrl(MSR_IA32_APERF, aperf);
> rdmsrl(MSR_IA32_MPERF, mperf);
>
> - acnt = aperf - this_cpu_read(arch_prev_aperf);
> - mcnt = mperf - this_cpu_read(arch_prev_mperf);
> + acnt = aperf - s->aperf;
> + mcnt = mperf - s->mperf;
>
> - this_cpu_write(arch_prev_aperf, aperf);
> - this_cpu_write(arch_prev_mperf, mperf);
> + s->aperf = aperf;
> + s->mperf = mperf;
>
> if (check_shl_overflow(acnt, 2*SCHED_CAPACITY_SHIFT, &acnt))
> goto error;
>