lkml.org 
[lkml]   [2023]   [Oct]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    SubjectRe: [RFC v3 6/6] arm64/amu: use capacity_ref_freq to set AMU ratio
    Hi,

    On Wednesday 18 Oct 2023 at 18:25:40 (+0200), Vincent Guittot wrote:
    > Use the new capacity_ref_freq to set the ratio that is used by AMU for
    > computing the arch_scale_freq_capacity().
    > This helps to keep everything aligned using the same reference for
    > computing CPUs capacity.
    >
    > The default value of the ratio ensures that arch_scale_freq_capacity()
    > returns max capacity until it is set to its correct value with the
    > cpu capacity and capacity_ref_freq.
    >
    > Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
    > ---
    > arch/arm64/kernel/topology.c | 18 ++++++++++--------
    > drivers/base/arch_topology.c | 14 ++++++++++++--
    > include/linux/arch_topology.h | 1 +
    > 3 files changed, 23 insertions(+), 10 deletions(-)
    >
    > diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
    > index 817d788cd866..0f8f6e90c46d 100644
    > --- a/arch/arm64/kernel/topology.c
    > +++ b/arch/arm64/kernel/topology.c
    > @@ -82,7 +82,12 @@ int __init parse_acpi_topology(void)
    > #undef pr_fmt
    > #define pr_fmt(fmt) "AMU: " fmt
    >
    > -static DEFINE_PER_CPU_READ_MOSTLY(unsigned long, arch_max_freq_scale);
    > +/*
    > + * Ensure that amu_scale_freq_tick() will return SCHED_CAPACITY_SHIFT until
    > + * the CPU capacity and its assosciated frequency have been correctly
    > + * initialized.

    s/SCHED_CAPACITY_SHIFT/SCHED_CAPACITY_SCALE

    > + */
    > +static DEFINE_PER_CPU_READ_MOSTLY(unsigned long, arch_max_freq_scale) = (2 * SCHED_CAPACITY_SHIFT);

    It should be 1UL << (2 * SCHED_CAPACITY_SHIFT).

    > static DEFINE_PER_CPU(u64, arch_const_cycles_prev);
    > static DEFINE_PER_CPU(u64, arch_core_cycles_prev);
    > static cpumask_var_t amu_fie_cpus;
    > @@ -112,9 +117,9 @@ static inline bool freq_counters_valid(int cpu)
    > return true;
    > }
    >
    > -static int freq_inv_set_max_ratio(int cpu, u64 max_rate, u64 ref_rate)
    > +int freq_inv_set_max_ratio(int cpu, u64 max_rate)
    > {
    > - u64 ratio;
    > + u64 ratio, ref_rate = arch_timer_get_rate();
    >
    > if (unlikely(!max_rate || !ref_rate)) {
    > pr_debug("CPU%d: invalid maximum or reference frequency.\n",
    > @@ -142,7 +147,7 @@ static int freq_inv_set_max_ratio(int cpu, u64 max_rate, u64 ref_rate)
    > return -EINVAL;
    > }

    The return value is no longer used so it might be worth declaring it to
    return void and WARN_ONCE for unlikely(!max_rate || !ref_rate).

    >
    > - per_cpu(arch_max_freq_scale, cpu) = (unsigned long)ratio;
    > + WRITE_ONCE(per_cpu(arch_max_freq_scale, cpu), (unsigned long)ratio);
    >
    > return 0;
    > }
    > @@ -195,10 +200,7 @@ static void amu_fie_setup(const struct cpumask *cpus)
    > return;
    >
    > for_each_cpu(cpu, cpus) {
    > - if (!freq_counters_valid(cpu) ||
    > - freq_inv_set_max_ratio(cpu,
    > - cpufreq_get_hw_max_freq(cpu) * 1000ULL,
    > - arch_timer_get_rate()))
    > + if (!freq_counters_valid(cpu))
    > return;
    > }
    >
    > diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
    > index 2372ce791bb4..3a604b77b12d 100644
    > --- a/drivers/base/arch_topology.c
    > +++ b/drivers/base/arch_topology.c
    > @@ -344,6 +344,11 @@ bool __init topology_parse_cpu_capacity(struct device_node *cpu_node, int cpu)
    > return !ret;
    > }
    >
    > +int __weak freq_inv_set_max_ratio(int cpu, u64 max_rate)
    > +{
    > + return 0;
    > +}
    > +
    > #ifdef CONFIG_ACPI_CPPC_LIB
    > #include <acpi/cppc_acpi.h>
    >
    > @@ -369,7 +374,6 @@ void topology_init_cpu_capacity_cppc(void)
    > capacity_scale = max_t(u64, capacity_scale, raw_capacity[cpu]);
    >
    > per_cpu(capacity_ref_freq, cpu) = cppc_perf_to_khz(&perf_caps, raw_capacity[cpu]);
    > -
    > pr_debug("cpu_capacity: CPU%d cpu_capacity=%u (raw).\n",
    > cpu, raw_capacity[cpu]);
    > continue;
    > @@ -381,6 +385,9 @@ void topology_init_cpu_capacity_cppc(void)
    > }
    >
    > for_each_possible_cpu(cpu) {
    > + freq_inv_set_max_ratio(cpu,
    > + per_cpu(capacity_ref_freq, cpu));
    > +
    > capacity = raw_capacity[cpu];
    > capacity = div64_u64(capacity << SCHED_CAPACITY_SHIFT,
    > capacity_scale);
    > @@ -422,8 +429,11 @@ init_cpu_capacity_callback(struct notifier_block *nb,
    >
    > cpumask_andnot(cpus_to_visit, cpus_to_visit, policy->related_cpus);
    >
    > - for_each_cpu(cpu, policy->related_cpus)
    > + for_each_cpu(cpu, policy->related_cpus) {
    > per_cpu(capacity_ref_freq, cpu) = policy->cpuinfo.max_freq;
    > + freq_inv_set_max_ratio(cpu,
    > + per_cpu(capacity_ref_freq, cpu));

    capacity_ref_freq is in KHz while arch_timer_get_rate() is in Hz. One or
    the other needs to be scaled.

    The same in topology_init_cpu_capacity_cppc().

    Thanks,
    Ionela.

    > + }
    >
    > if (cpumask_empty(cpus_to_visit)) {
    > topology_normalize_cpu_scale();
    > diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h
    > index 38ca6c76af56..b6e95d763279 100644
    > --- a/include/linux/arch_topology.h
    > +++ b/include/linux/arch_topology.h
    > @@ -99,6 +99,7 @@ void update_siblings_masks(unsigned int cpu);
    > void remove_cpu_topology(unsigned int cpuid);
    > void reset_cpu_topology(void);
    > int parse_acpi_topology(void);
    > +int freq_inv_set_max_ratio(int cpu, u64 max_rate);
    > #endif
    >
    > #endif /* _LINUX_ARCH_TOPOLOGY_H_ */
    > --
    > 2.34.1
    >

    \
     
     \ /
      Last update: 2023-10-23 22:59    [W:4.118 / U:0.028 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site