Split out SystemLoad alerts for Nova Compute nodes.

Fixes PROD-34626

Change-Id: Iee4617067e1f491ffc46ddacbbb2c8d517fe3766
diff --git a/nova/meta/prometheus.yml b/nova/meta/prometheus.yml
index cc48363..04d3384 100644
--- a/nova/meta/prometheus.yml
+++ b/nova/meta/prometheus.yml
@@ -389,6 +389,30 @@
           All {{ $labels.binary }} services are down.
 {%- endraw %}
 {%- endif %}
+{%- if is_compute %}
+{%- raw %}
+    NovaComputeSystemLoadTooHighWarning:
+      if: >-
+        system_load15{host=~".*cmp[0-9]+"} / system_n_cpus > 1.0
+      for: 5m
+      labels:
+        severity: warning
+        service: system
+      annotations:
+        summary: "System load is 1.0"
+        description: "The system load per CPU on the {{ $labels.host }} node is {{ $value }} for 5 minutes."
+    NovaComputeSystemLoadTooHighCritical:
+      if: >-
+        system_load15{host=~".*cmp[0-9]+"} / system_n_cpus > 2.0
+      for: 5m
+      labels:
+        severity: critical
+        service: system
+      annotations:
+        summary: "System load is 2.0"
+        description: "The system load per CPU on the {{ $labels.host }} node is {{ $value }} for 5 minutes."
+{%- endraw %}
+{%- endif %}
 {%- raw %}
     NovaErrorLogsTooHigh:
       if: >-