Extending cpufreq plugin to read the following additional metrics:

  - number of p-state(cpu frequency) transitions
  - time spent in each p-state

Both metrics are reported by the Linux cpufreq-stats driver:
https://www.kernel.org/doc/Documentation/cpu-freq/cpufreq-stats.txt

diff --git a/src/cpufreq.c b/src/cpufreq.c
index 851aad4..aa969b0 100644 (file)
--- a/src/cpufreq.c
+++ b/src/cpufreq.c
@@ -25,8 +25,71 @@
 #include "common.h"
 #include "plugin.h"
 
+#define MAX_AVAIL_FREQS 20
+
 static int num_cpu;
 
+struct thread_data {
+  long long time_prev[MAX_AVAIL_FREQS];
+  long long transitions;
+} *t_data;
+
+/* Flags denoting capability of reporting stats. */
+unsigned report_time_in_state, report_total_trans;
+
+static int counter_init(void){
+  t_data = calloc(num_cpu, sizeof(struct thread_data));
+  if (t_data == NULL)
+       return 0;
+
+  report_time_in_state = 1;
+  report_total_trans = 1;
+
+  /* Initialize time in state counters */
+  for (int i = 0; i < num_cpu; i++) {
+    char filename[256];
+    FILE *fh;
+    int j = 0;
+    char state[DATA_MAX_NAME_LEN], buffer[DATA_MAX_NAME_LEN];
+    long long t;
+
+    snprintf(filename, sizeof(filename),
+              "/sys/devices/system/cpu/cpu%d/cpufreq/stats/time_in_state", i);
+    fh = fopen(filename, "r");
+    if (fh == NULL) {
+      report_time_in_state = 0;
+      return 0;
+    }
+    while (fgets(buffer, sizeof(buffer), fh) != NULL) {
+      if (!sscanf(buffer, "%s%lli", state, &t)) {
+        fclose(fh);
+       return 0;
+      }
+      t_data[i].time_prev[j] = t;
+      j++;
+    }
+    fclose(fh);
+
+    /* Initialize total transitions for cpu frequency */
+    snprintf(filename, sizeof(filename),
+              "/sys/devices/system/cpu/cpu%d/cpufreq/stats/total_trans", i);
+    fh = fopen(filename, "r");
+    if (fh == NULL) {
+      report_total_trans = 0;
+      return 0;
+    }
+    while (fgets(buffer, sizeof(buffer), fh) != NULL) {
+      if (!sscanf(buffer, "%lli", &t)) {
+        fclose(fh);
+        return 0;
+      }
+      t_data[i].transitions = t;
+    }
+    fclose(fh);
+  }
+  return 0;
+}
+
 static int cpufreq_init(void) {
   int status;
   char filename[256];
@@ -48,6 +111,7 @@ static int cpufreq_init(void) {
   }
 
   INFO("cpufreq plugin: Found %d CPU%s", num_cpu, (num_cpu == 1) ? "" : "s");
+  counter_init();
 
   if (num_cpu == 0)
     plugin_unregister_read("cpufreq");
@@ -55,14 +119,17 @@ static int cpufreq_init(void) {
   return 0;
 } /* int cpufreq_init */
 
-static void cpufreq_submit(int cpu_num, value_t value) {
+static void cpufreq_submit(int cpu_num, const char *type, const char *type_instance, value_t value) {
   value_list_t vl = VALUE_LIST_INIT;
 
   vl.values = &value;
   vl.values_len = 1;
   sstrncpy(vl.plugin, "cpufreq", sizeof(vl.plugin));
-  sstrncpy(vl.type, "cpufreq", sizeof(vl.type));
-  snprintf(vl.type_instance, sizeof(vl.type_instance), "%i", cpu_num);
+  snprintf(vl.plugin_instance, sizeof(vl.plugin_instance), "%i", cpu_num);
+  if (type != NULL)
+    sstrncpy(vl.type, type, sizeof(vl.type));
+  if (type_instance != NULL)
+  sstrncpy(vl.type_instance, type_instance, sizeof(vl.type_instance));
 
   plugin_dispatch_values(&vl);
 }
@@ -70,6 +137,10 @@ static void cpufreq_submit(int cpu_num, value_t value) {
 static int cpufreq_read(void) {
   for (int i = 0; i < num_cpu; i++) {
     char filename[PATH_MAX];
+    FILE *fh;
+    long long t;
+    char buffer[DATA_MAX_NAME_LEN];
+    /* Read cpu frequency */
     snprintf(filename, sizeof(filename),
              "/sys/devices/system/cpu/cpu%d/cpufreq/scaling_cur_freq", i);
 
@@ -82,9 +153,64 @@ static int cpufreq_read(void) {
     /* convert kHz to Hz */
     v.gauge *= 1000.0;
 
-    cpufreq_submit(i, v);
-  }
+    cpufreq_submit(i, "cpufreq", NULL, v);
+
+    /* Read total transitions for cpu frequency */
+    if (report_total_trans) {
+      snprintf(filename, sizeof(filename),
+                "/sys/devices/system/cpu/cpu%d/cpufreq/stats/total_trans", i);
+      fh = fopen(filename, "r");
+      if (fh == NULL)
+        continue;
+      while (fgets(buffer, sizeof(buffer), fh) != NULL) {
+        if (!sscanf(buffer, "%lli", &t)) {
+          fclose(fh);
+         return 0;
+       }
+        snprintf(buffer, sizeof(buffer), "%lli", t - t_data[i].transitions);
+        t_data[i].transitions = t;
+      }
+      if (parse_value(buffer, &v, DS_TYPE_GAUGE) != 0) {
+        WARNING("cpufreq plugin: Reading \"%s\" failed.", filename);
+       fclose(fh);
+        continue;
+      }
+      fclose(fh);
+
+      cpufreq_submit(i, "transitions", NULL, v);
+    }
 
+    /* Determine time in state for cpu during previous interval
+     * Reported in 10mS as unit.
+     */
+    if (report_time_in_state) {
+      int j = 0;
+      char state[DATA_MAX_NAME_LEN], time[DATA_MAX_NAME_LEN];
+      value_t val;
+
+      snprintf(filename, sizeof(filename),
+              "/sys/devices/system/cpu/cpu%d/cpufreq/stats/time_in_state", i);
+      fh = fopen(filename, "r");
+      if (fh == NULL)
+        continue;
+      while (fgets(buffer, sizeof(buffer), fh) != NULL) {
+        if (!sscanf(buffer, "%s%lli", state, &t)) {
+         fclose(fh);
+          return 0;
+       }
+        snprintf(time, sizeof(time), "%lli", t - t_data[i].time_prev[j]);
+        if (parse_value(time, &val, DS_TYPE_GAUGE) != 0) {
+          WARNING("cpufreq plugin: Reading \"%s\" failed.", filename);
+         fclose(fh);
+          continue;
+        }
+        cpufreq_submit(i, "time_in_state", state, val);
+        t_data[i].time_prev[j] = t;
+        j++;
+      }
+      fclose(fh);
+    }
+  }
   return 0;
 } /* int cpufreq_read */
 

diff --git a/src/types.db b/src/types.db
index 0370b7f..291467f 100644 (file)
--- a/src/types.db
+++ b/src/types.db
@@ -244,6 +244,7 @@ tdp                     value:GAUGE:U:U
 temperature             value:GAUGE:U:U
 threads                 value:GAUGE:0:U
 time_dispersion         value:GAUGE:-1000000:1000000
+time_in_state           value:GAUGE:0:U
 time_offset             value:GAUGE:-1000000:1000000
 time_offset_ntp         value:GAUGE:-1000000:1000000
 time_offset_rms         value:GAUGE:-1000000:1000000
@@ -260,6 +261,7 @@ total_threads           value:DERIVE:0:U
 total_time_in_ms        value:DERIVE:0:U
 total_values            value:DERIVE:0:U
 turbo_enabled           value:GAUGE:0:1
+transitions             value:GAUGE:0:U
 uptime                  value:GAUGE:0:4294967295
 uncore_ratio            value:GAUGE:0:U
 users                   value:GAUGE:0:65535