Adding upstream version 18.2.2.upstream/18.2.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 247 insertions, 0 deletions

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+===============
+ Perf counters
+===============
+
+The perf counters provide generic internal infrastructure for gauges and counters.  The counted values can be both integer and float. There is also an "average" type (normally float) that combines a sum and num counter which can be divided to provide an average.
+
+The intention is that this data will be collected and aggregated by a tool like ``collectd`` or ``statsd`` and fed into a tool like ``graphite`` for graphing and analysis.  Also, note the :doc:`../mgr/prometheus` and the :doc:`../mgr/telemetry`.
+
+Users and developers can also access perf counter data locally to check a cluster's overall health, identify workload patterns, monitor cluster performance by daemon types, and troubleshoot issues with latency, throttling, memory management, etc. (see :ref:`Access`)
+
+.. _Access:
+
+Access
+------
+
+The perf counter data is accessed via the admin socket.  For example::
+
+   ceph daemon osd.0 perf schema
+   ceph daemon osd.0 perf dump
+
+
+Collections
+-----------
+
+The values are grouped into named collections, normally representing a subsystem or an instance of a subsystem.  For example, the internal ``throttle`` mechanism reports statistics on how it is throttling, and each instance is named something like::
+
+
+    throttle-msgr_dispatch_throttler-hbserver
+    throttle-msgr_dispatch_throttler-client
+    throttle-filestore_bytes
+    ...
+
+
+Schema
+------
+
+The ``perf schema`` command dumps a json description of which values are available, and what their type is.  Each named value as a ``type`` bitfield, with the following bits defined.
+
++------+-------------------------------------+
+| bit  | meaning                             |
++======+=====================================+
+| 1    | floating point value                |
++------+-------------------------------------+
+| 2    | unsigned 64-bit integer value       |
++------+-------------------------------------+
+| 4    | average (sum + count pair), where   |
++------+-------------------------------------+
+| 8    | counter (vs gauge)                  |
++------+-------------------------------------+
+
+Every value will have either bit 1 or 2 set to indicate the type
+(float or integer).
+
+If bit 8 is set (counter), the value is monotonically increasing and
+the reader may want to subtract off the previously read value to get
+the delta during the previous interval.
+
+If bit 4 is set (average), there will be two values to read, a sum and
+a count.  If it is a counter, the average for the previous interval
+would be sum delta (since the previous read) divided by the count
+delta.  Alternatively, dividing the values outright would provide the
+lifetime average value.  Normally these are used to measure latencies
+(number of requests and a sum of request latencies), and the average
+for the previous interval is what is interesting.
+
+Instead of interpreting the bit fields, the ``metric type`` has a
+value of either ``gauge`` or ``counter``, and the ``value type``
+property will be one of ``real``, ``integer``, ``real-integer-pair``
+(for a sum + real count pair), or ``integer-integer-pair`` (for a
+sum + integer count pair).
+
+Here is an example of the schema output::
+
+  {
+    "throttle-bluestore_throttle_bytes": {
+        "val": {
+            "type": 2,
+            "metric_type": "gauge",
+            "value_type": "integer",
+            "description": "Currently available throttle",
+            "nick": ""
+        },
+        "max": {
+            "type": 2,
+            "metric_type": "gauge",
+            "value_type": "integer",
+            "description": "Max value for throttle",
+            "nick": ""
+        },
+        "get_started": {
+            "type": 10,
+            "metric_type": "counter",
+            "value_type": "integer",
+            "description": "Number of get calls, increased before wait",
+            "nick": ""
+        },
+        "get": {
+            "type": 10,
+            "metric_type": "counter",
+            "value_type": "integer",
+            "description": "Gets",
+            "nick": ""
+        },
+        "get_sum": {
+            "type": 10,
+            "metric_type": "counter",
+            "value_type": "integer",
+            "description": "Got data",
+            "nick": ""
+        },
+        "get_or_fail_fail": {
+            "type": 10,
+            "metric_type": "counter",
+            "value_type": "integer",
+            "description": "Get blocked during get_or_fail",
+            "nick": ""
+        },
+        "get_or_fail_success": {
+            "type": 10,
+            "metric_type": "counter",
+            "value_type": "integer",
+            "description": "Successful get during get_or_fail",
+            "nick": ""
+        },
+        "take": {
+            "type": 10,
+            "metric_type": "counter",
+            "value_type": "integer",
+            "description": "Takes",
+            "nick": ""
+        },
+        "take_sum": {
+            "type": 10,
+            "metric_type": "counter",
+            "value_type": "integer",
+            "description": "Taken data",
+            "nick": ""
+        },
+        "put": {
+            "type": 10,
+            "metric_type": "counter",
+            "value_type": "integer",
+            "description": "Puts",
+            "nick": ""
+        },
+        "put_sum": {
+            "type": 10,
+            "metric_type": "counter",
+            "value_type": "integer",
+            "description": "Put data",
+            "nick": ""
+        },
+        "wait": {
+            "type": 5,
+            "metric_type": "gauge",
+            "value_type": "real-integer-pair",
+            "description": "Waiting latency",
+            "nick": ""
+        }
+  }
+
+
+Dump
+----
+
+The actual dump is similar to the schema, except that average values are grouped.  For example::
+
+ {
+   "throttle-msgr_dispatch_throttler-hbserver" : {
+      "get_or_fail_fail" : 0,
+      "get_sum" : 0,
+      "max" : 104857600,
+      "put" : 0,
+      "val" : 0,
+      "take" : 0,
+      "get_or_fail_success" : 0,
+      "wait" : {
+         "avgcount" : 0,
+         "sum" : 0
+      },
+      "get" : 0,
+      "take_sum" : 0,
+      "put_sum" : 0
+   },
+   "throttle-msgr_dispatch_throttler-client" : {
+      "get_or_fail_fail" : 0,
+      "get_sum" : 82760,
+      "max" : 104857600,
+      "put" : 2637,
+      "val" : 0,
+      "take" : 0,
+      "get_or_fail_success" : 0,
+      "wait" : {
+         "avgcount" : 0,
+         "sum" : 0
+      },
+      "get" : 2637,
+      "take_sum" : 0,
+      "put_sum" : 82760
+   }
+ }
+
+Labeled Perf Counters
+---------------------
+
+A Ceph daemon has the ability to emit a set of perf counter instances with varying labels. These counters are intended for visualizing specific metrics in 3rd party tools like Prometheus and Grafana.
+
+For example, the below counters show the number of put requests for different users on different buckets::
+
+  {
+      "rgw": [
+          {
+              "labels": {
+                  "Bucket: "bkt1",
+                  "User: "user1",
+              },
+              "counters": {
+                  "put": 1,
+              },
+          },
+          {
+              "labels": {},
+              "counters": {
+                  "put": 4,
+              },
+          },
+          {
+              "labels": {
+                  "Bucket: "bkt1",
+                  "User: "user2",
+              },
+              "counters": {
+                  "put": 3,
+              },
+          },
+      ]
+  }
+
+All labeled and unlabeled perf counters can be viewed with ``ceph daemon {daemon id} counter dump``. 
+
+All labeled and unlabeled perf counter's schema can be viewed with ``ceph daemon {daemon id} counter schema``.
+
+In the above example the second counter without labels is a counter that would also be shown in ``ceph daemon {daemon id} perf dump``.
+
+Since the ``counter dump`` and ``counter schema`` commands can be used to view both types of counters it is not recommended to use the ``perf dump`` and ``perf schema`` commands which are retained for backwards compatibility and continue to emit only non-labeled counters.
+
+Some perf counters that are emitted via ``perf dump`` and ``perf schema`` may become labeled in future releases and as such will no longer be emitted by ``perf dump`` and ``perf schema`` respectively.