turbostat plugin: add new setting `RestoreAffinityPolicy`

[collectd.git] / src / turbostat.c

diff --git a/src/turbostat.c b/src/turbostat.c
index 49c3968..ca87219 100644 (file)
--- a/src/turbostat.c
+++ b/src/turbostat.c
@@ -49,6 +49,15 @@
 
 #define PLUGIN_NAME "turbostat"
 
+typedef enum affinity_policy_enum {
+  policy_restore_affinity, /* restore cpu affinity to whatever it was before */
+  policy_allcpus_affinity, /* do not restore affinity, set to all cpus */
+  policy_invalid
+} affinity_policy_t;
+
+/* the default is to preserve cpu affinity */
+static affinity_policy_t affinity_policy = policy_restore_affinity;
+
 /*
  * This tool uses the Model-Specific Registers (MSRs) present on Intel
  * processors.
@@ -244,6 +253,7 @@ static const char *config_keys[] = {
     "TCCActivationTemp",
     "RunningAveragePowerLimit",
     "LogicalCoreNames",
+    "RestoreAffinityPolicy",
 };
 static const int config_keys_num = STATIC_ARRAY_SIZE(config_keys);
 
@@ -1454,6 +1464,30 @@ err:
   return ret;
 }
 
+int save_affinity(void) {
+  if (affinity_policy == policy_restore_affinity) {
+    /* Try to save the scheduling affinity, as it will be modified by
+    * get_counters.
+    */
+    if (sched_getaffinity(0, cpu_saved_affinity_setsize,
+                          cpu_saved_affinity_set) != 0)
+      return -1;
+  }
+
+  return 0;
+}
+
+void restore_affinity(void) {
+  /* Let's restore the affinity to the value saved in save_affinity */
+  if (affinity_policy == policy_restore_affinity)
+    (void)sched_setaffinity(0, cpu_saved_affinity_setsize,
+                            cpu_saved_affinity_set);
+  else {
+    /* reset the affinity to all present cpus */
+    (void)sched_setaffinity(0, cpu_present_setsize, cpu_present_set);
+  }
+}
+
 static int turbostat_read(void) {
   int ret;
 
@@ -1473,10 +1507,8 @@ static int turbostat_read(void) {
     }
   }
 
-  /* Saving the scheduling affinity, as it will be modified by get_counters */
-  if (sched_getaffinity(0, cpu_saved_affinity_setsize,
-                        cpu_saved_affinity_set) != 0) {
-    ERROR("turbostat plugin: Unable to save the CPU affinity: %s", STRERRNO);
+  if (save_affinity() != 0) {
+    ERROR("turbostat plugin: Unable to save the CPU affinity");
     return -1;
   }
 
@@ -1513,13 +1545,8 @@ static int turbostat_read(void) {
   }
   ret = 0;
 out:
-  /*
-   * Let's restore the affinity
-   * This might fail if the number of CPU changed, but we can't do anything in
-   * that case..
-   */
-  (void)sched_setaffinity(0, cpu_saved_affinity_setsize,
-                          cpu_saved_affinity_set);
+  restore_affinity();
+
   return ret;
 }
 
@@ -1590,6 +1617,15 @@ err:
   return ret;
 }
 
+affinity_policy_t parse_affinity_policy(const char *value) {
+  if (strcasecmp("AffinityRestore", value) == 0)
+    return policy_restore_affinity;
+  else if (strcasecmp("AffinityAllCPUs", value) == 0)
+    return policy_allcpus_affinity;
+
+  return policy_invalid;
+}
+
 static int turbostat_config(const char *key, const char *value) {
   long unsigned int tmp_val;
   char *end;
@@ -1636,6 +1672,13 @@ static int turbostat_config(const char *key, const char *value) {
       return -1;
     }
     tcc_activation_temp = (unsigned int)tmp_val;
+  } else if (strcasecmp("RestoreAffinityPolicy", key) == 0) {
+    affinity_policy = parse_affinity_policy(value);
+    if (affinity_policy == policy_invalid) {
+      /* set to default policy if requested policy is invalid */
+      affinity_policy = policy_restore_affinity;
+      ERROR("turbostat plugin: Invalid RestoreAffinityPolicy '%s'", value);
+    }
   } else {
     ERROR("turbostat plugin: Invalid configuration option '%s'", key);
     return -1;