Defined constants that help in scheduling of tasks.

constants/constants.go

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+/*
+Constants that are used across scripts
+1. The available hosts = stratos-00x (x varies from 1 to 8)
+2. cap_margin = percentage of the requested power to allocate
+3. power_threshold = overloading factor
+4. total_power = total power per node
+5. window_size = number of tasks to consider for computation of the dynamic cap.
+
+Also, exposing functions to update or initialize some of the constants.
+*/
+package constants
+
+var Hosts = []string{"stratos-001", "stratos-002",
+            "stratos-003", "stratos-004",
+            "stratos-005", "stratos-006",
+            "stratos-007", "stratos-008"}
+
+// Add a new host to the slice of hosts.
+func AddNewHost(new_host string) bool {
+  // Validation
+  if new_host == "" {
+    return false
+  } else {
+    Hosts = append(Hosts, new_host)
+    return true
+  }
+}
+
+// Lower bound of the percentage of requested power, that can be allocated to a task.
+var Power_threshold = 0.6 // Right now saying that a task will never be given lesser than 60% of the power it requested.
+
+/*
+  Margin with respect to the required power for a job.
+  So, if power required = 10W, the node would be capped to 75%*10W.
+  This value can be changed upon convenience.
+*/
+var Cap_margin = 0.75
+
+// Modify the cap margin.
+func UpdateCapMargin(new_cap_margin float64) bool {
+  // Checking if the new_cap_margin is less than the power threshold.
+  if new_cap_margin < Starvation_factor {
+    return false
+  } else {
+    Cap_margin = new_cap_margin
+    return true
+  }
+}
+
+
+// Threshold factor that would make (Cap_margin * task.Watts) equal to (60/100 * task.Watts).
+var Starvation_factor = 0.8
+
+// Total power per node.
+var Total_power map[string]float64
+
+// Initialize the total power per node. This should be done before accepting any set of tasks for scheduling.
+func AddTotalPowerForHost(host string, total_power float64) bool {
+  // Validation
+  is_correct_host := false
+  for _, existing_host := range Hosts {
+    if host == existing_host {
+      is_correct_host = true
+    }
+  }
+
+  if !is_correct_host {
+    return false
+  } else {
+    Total_power[host] = total_power
+    return true
+  }
+}
+
+// Window size for running average
+var Window_size = 10
+
+// Update the window size.
+func UpdateWindowSize(new_window_size int) bool {
+  // Validation
+  if new_window_size == 0 {
+      return false
+  } else{
+    Window_size = new_window_size
+    return true
+  }
+}
+
+// Time duration between successive cluster wide capping.
+var Clusterwide_cap_interval = 10.0 // Right now capping the cluster at 10 second intervals.
+
+// Modify the cluster wide capping interval. We can update the interval depending on the workload.
+// TODO: If the workload is heavy then we can set a longer interval, while on the other hand,
+//  if the workload is light then a smaller interval is sufficient.
+func UpdateClusterwideCapInterval(new_interval float64) bool {
+  // Validation
+  if new_interval == 0.0 {
+    return false
+  } else {
+    Clusterwide_cap_interval = new_interval
+    return true
+  }
+}