@@ -248,6 +248,20 @@ are the following:
If that frequency cannot be determined, this attribute should not
be present.
+``cpuinfo_avg_freq``
+ An average frequency (in KHz) of all CPUs belonging to a given policy,
+ derived from a hardware provided feedback and reported on a time frame
+ spanning at most few milliseconds.
+
+ This is expected to be based on the frequency the hardware actually runs
+ at and, as such, might require specialised hardware support (such as AMU
+ extension on ARM). If one cannot be determined, this attribute should
+ not be present.
+
+ Note, that failed attempt to retrieve current frequency for a given
+ CPU(s) will result in an appropriate error, i.e: EAGAIN for CPU that
+ remains idle (raised on ARM).
+
``cpuinfo_max_freq``
Maximum possible operating frequency the CPUs belonging to this policy
can run at (in kHz).
@@ -293,7 +307,8 @@ are the following:
Some architectures (e.g. ``x86``) may attempt to provide information
more precisely reflecting the current CPU frequency through this
attribute, but that still may not be the exact current CPU frequency as
- seen by the hardware at the moment.
+ seen by the hardware at the moment. This behavior though, is only
+ available via c:macro:``CPUFREQ_ARCH_CUR_FREQ`` option.
``scaling_driver``
The scaling driver currently in use.
@@ -340,3 +340,15 @@ config X86_SPEEDSTEP_RELAXED_CAP_CHECK
option lets the probing code bypass some of those checks if the
parameter "relaxed_check=1" is passed to the module.
+config CPUFREQ_ARCH_CUR_FREQ
+ default y
+ bool "Current frequency derived from HW provided feedback"
+ help
+ This determines whether the scaling_cur_freq sysfs attribute returns
+ the last requested frequency or a more precise value based on hardware
+ provided feedback (as architected counters).
+ Given that a more precise frequency can now be provided via the
+ cpuinfo_avg_freq attribute, by enabling this option,
+ scaling_cur_freq maintains the provision of a counter based frequency,
+ for compatibility reasons.
+
@@ -734,12 +734,20 @@ __weak int arch_freq_get_on_cpu(int cpu)
return -EOPNOTSUPP;
}
+static inline bool cpufreq_avg_freq_supported(struct cpufreq_policy *policy)
+{
+ return arch_freq_get_on_cpu(policy->cpu) != -EOPNOTSUPP;
+}
+
static ssize_t show_scaling_cur_freq(struct cpufreq_policy *policy, char *buf)
{
ssize_t ret;
int freq;
- freq = arch_freq_get_on_cpu(policy->cpu);
+ freq = IS_ENABLED(CONFIG_CPUFREQ_ARCH_CUR_FREQ)
+ ? arch_freq_get_on_cpu(policy->cpu)
+ : 0;
+
if (freq > 0)
ret = sysfs_emit(buf, "%u\n", freq);
else if (cpufreq_driver->setpolicy && cpufreq_driver->get)
@@ -784,6 +792,19 @@ static ssize_t show_cpuinfo_cur_freq(struct cpufreq_policy *policy,
return sysfs_emit(buf, "<unknown>\n");
}
+/*
+ * show_cpuinfo_avg_freq - average CPU frequency as detected by hardware
+ */
+static ssize_t show_cpuinfo_avg_freq(struct cpufreq_policy *policy,
+ char *buf)
+{
+ int avg_freq = arch_freq_get_on_cpu(policy->cpu);
+
+ if (avg_freq > 0)
+ return sysfs_emit(buf, "%u\n", avg_freq);
+ return avg_freq != 0 ? avg_freq : -EINVAL;
+}
+
/*
* show_scaling_governor - show the current policy for the specified CPU
*/
@@ -946,6 +967,7 @@ static ssize_t show_bios_limit(struct cpufreq_policy *policy, char *buf)
}
cpufreq_freq_attr_ro_perm(cpuinfo_cur_freq, 0400);
+cpufreq_freq_attr_ro(cpuinfo_avg_freq);
cpufreq_freq_attr_ro(cpuinfo_min_freq);
cpufreq_freq_attr_ro(cpuinfo_max_freq);
cpufreq_freq_attr_ro(cpuinfo_transition_latency);
@@ -1073,6 +1095,12 @@ static int cpufreq_add_dev_interface(struct cpufreq_policy *policy)
return ret;
}
+ if (cpufreq_avg_freq_supported(policy)) {
+ ret = sysfs_create_file(&policy->kobj, &cpuinfo_avg_freq.attr);
+ if (ret)
+ return ret;
+ }
+
ret = sysfs_create_file(&policy->kobj, &scaling_cur_freq.attr);
if (ret)
return ret;