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Subject[PATCH v2 2/3] arm64: split counter validation function
Date
In order for the counter validation function to be reused, split
validate_cpu_freq_invariance_counters() into:
- freq_counters_valid(cpu) - check cpu for valid cycle counters
- freq_inv_set_max_ratio(int cpu, u64 max_rate, u64 ref_rate) -
generic function that sets the normalization ratio used by
topology_scale_freq_tick()

Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
---
arch/arm64/kernel/topology.c | 44 +++++++++++++++++++++---------------
1 file changed, 26 insertions(+), 18 deletions(-)

diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
index db03c440e157..764fdb0f947b 100644
--- a/arch/arm64/kernel/topology.c
+++ b/arch/arm64/kernel/topology.c
@@ -152,45 +152,49 @@ void update_freq_counters_refs(void)
this_cpu_write(arch_const_cycles_prev, read_constcnt());
}

-static int validate_cpu_freq_invariance_counters(int cpu)
+static inline bool freq_counters_valid(int cpu)
{
- u64 max_freq_hz, ratio;
-
if (!cpu_has_amu_feat(cpu)) {
pr_debug("CPU%d: counters are not supported.\n", cpu);
- return -EINVAL;
+ return false;
}

if (unlikely(!per_cpu(arch_const_cycles_prev, cpu) ||
!per_cpu(arch_core_cycles_prev, cpu))) {
pr_debug("CPU%d: cycle counters are not enabled.\n", cpu);
- return -EINVAL;
+ return false;
}

- /* Convert maximum frequency from KHz to Hz and validate */
- max_freq_hz = cpufreq_get_hw_max_freq(cpu) * 1000;
- if (unlikely(!max_freq_hz)) {
- pr_debug("CPU%d: invalid maximum frequency.\n", cpu);
+ return true;
+}
+
+static int freq_inv_set_max_ratio(int cpu, u64 max_rate, u64 ref_rate)
+{
+ u64 ratio;
+
+ if (unlikely(!max_rate || !ref_rate)) {
+ pr_debug("CPU%d: invalid maximum or reference frequency.\n",
+ cpu);
return -EINVAL;
}

/*
* Pre-compute the fixed ratio between the frequency of the constant
- * counter and the maximum frequency of the CPU.
+ * reference counter and the maximum frequency of the CPU.
*
- * const_freq
- * arch_max_freq_scale = ---------------- * SCHED_CAPACITY_SCALE²
- * cpuinfo_max_freq
+ * ref_rate
+ * arch_max_freq_scale = ---------- * SCHED_CAPACITY_SCALE²
+ * max_rate
*
* We use a factor of 2 * SCHED_CAPACITY_SHIFT -> SCHED_CAPACITY_SCALE²
* in order to ensure a good resolution for arch_max_freq_scale for
- * very low arch timer frequencies (down to the KHz range which should
+ * very low reference frequencies (down to the KHz range which should
* be unlikely).
*/
- ratio = (u64)arch_timer_get_rate() << (2 * SCHED_CAPACITY_SHIFT);
- ratio = div64_u64(ratio, max_freq_hz);
+ ratio = ref_rate << (2 * SCHED_CAPACITY_SHIFT);
+ ratio = div64_u64(ratio, max_rate);
if (!ratio) {
- WARN_ONCE(1, "System timer frequency too low.\n");
+ WARN_ONCE(1, "Reference frequency too low.\n");
return -EINVAL;
}

@@ -237,8 +241,12 @@ static int __init init_amu_fie(void)
}

for_each_present_cpu(cpu) {
- if (validate_cpu_freq_invariance_counters(cpu))
+ if (!freq_counters_valid(cpu) ||
+ freq_inv_set_max_ratio(cpu,
+ cpufreq_get_hw_max_freq(cpu) * 1000,
+ arch_timer_get_rate()))
continue;
+
cpumask_set_cpu(cpu, valid_cpus);
have_policy |= enable_policy_freq_counters(cpu, valid_cpus);
}
--
2.17.1
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