--- /dev/null
+===============
+ 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`.
+
+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 ``guage`` 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
+ }
+ }
+
Code Review / stor4nfv.git / blobdiff