Add bcache collector (#597)
* Add bcache collector for Linux
This collector gathers metrics related to the Linux block cache
(bcache) from sysfs.
* Removed commented out code
* Use project comment style
* Add _sectors to metric name to indicate unit
* Really use project comment style
* Rename bcache.go to bcache_linux.go
* Keep collector namespace clean
Rename:
- metric -> bcacheMetric
- periodStatsToMetrics -> bcachePeriodStatsToMetric
* Shorten slice initialization
* Change label names to backing_device, cache_device
* Remove five minute metrics (keep only total)
* Include units in additional metric names
* Enable bcache collector by default
* Provide metrics in seconds, not nanoseconds
* remove metrics with label "all"
* Add fixtures, update end-to-end for bcache collector
* Move fixtures/sys into tar.gz
This changeset moves the collector/fixtures/sys directory into
collector/fixtures/sys.tar.gz and tweaks the Makefile to unpack the
tarball before tests are run.
The reason for this change is that Windows does not allow colons in a
path (colons are present in some of the bcache fixture files), nor can
it (out of the box) deal with pathnames longer than 260 characters
(which we would be increasingly likely to hit if we tried to replace
colons with longer codes that are guaranteed not the turn up in regular
file names).
* Add ttar: plain text archive, replacement for tar
This changeset adds ttar, a plain text replacement for tar, and uses it
for the sysfs fixture archive. The syntax is loosely based on tar(1).
Using a plain text archive makes it possible to review changes without
downloading and extracting the archive. Also, when working on the repo,
git diff and git log become useful again, allowing a committer to verify
and track changes over time.
The code is written in bash, because bash is available out of the box on
all major flavors of Linux and on macOS. The feature set used is
restricted to bash version 3.2 because that is what Apple is still
shipping.
The programm also works on Windows if bash is installed. Obviously, it
does not solve the Windows limitations (path length limited to 260
characters, no symbolic links) that prompted the move to an archive
format in the first place.
2017-07-07 07:20:18 +02:00
// Copyright 2017 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// +build !nobcache
package collector
import (
"fmt"
// https://godoc.org/github.com/prometheus/client_golang/prometheus
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/procfs/bcache"
"github.com/prometheus/procfs/sysfs"
)
func init ( ) {
2017-09-28 15:06:26 +02:00
registerCollector ( "bcache" , defaultEnabled , NewBcacheCollector )
Add bcache collector (#597)
* Add bcache collector for Linux
This collector gathers metrics related to the Linux block cache
(bcache) from sysfs.
* Removed commented out code
* Use project comment style
* Add _sectors to metric name to indicate unit
* Really use project comment style
* Rename bcache.go to bcache_linux.go
* Keep collector namespace clean
Rename:
- metric -> bcacheMetric
- periodStatsToMetrics -> bcachePeriodStatsToMetric
* Shorten slice initialization
* Change label names to backing_device, cache_device
* Remove five minute metrics (keep only total)
* Include units in additional metric names
* Enable bcache collector by default
* Provide metrics in seconds, not nanoseconds
* remove metrics with label "all"
* Add fixtures, update end-to-end for bcache collector
* Move fixtures/sys into tar.gz
This changeset moves the collector/fixtures/sys directory into
collector/fixtures/sys.tar.gz and tweaks the Makefile to unpack the
tarball before tests are run.
The reason for this change is that Windows does not allow colons in a
path (colons are present in some of the bcache fixture files), nor can
it (out of the box) deal with pathnames longer than 260 characters
(which we would be increasingly likely to hit if we tried to replace
colons with longer codes that are guaranteed not the turn up in regular
file names).
* Add ttar: plain text archive, replacement for tar
This changeset adds ttar, a plain text replacement for tar, and uses it
for the sysfs fixture archive. The syntax is loosely based on tar(1).
Using a plain text archive makes it possible to review changes without
downloading and extracting the archive. Also, when working on the repo,
git diff and git log become useful again, allowing a committer to verify
and track changes over time.
The code is written in bash, because bash is available out of the box on
all major flavors of Linux and on macOS. The feature set used is
restricted to bash version 3.2 because that is what Apple is still
shipping.
The programm also works on Windows if bash is installed. Obviously, it
does not solve the Windows limitations (path length limited to 260
characters, no symbolic links) that prompted the move to an archive
format in the first place.
2017-07-07 07:20:18 +02:00
}
// A bcacheCollector is a Collector which gathers metrics from Linux bcache.
type bcacheCollector struct {
fs sysfs . FS
}
// NewBcacheCollector returns a newly allocated bcacheCollector.
// It exposes a number of Linux bcache statistics.
func NewBcacheCollector ( ) ( Collector , error ) {
fs , err := sysfs . NewFS ( * sysPath )
if err != nil {
return nil , fmt . Errorf ( "failed to open sysfs: %v" , err )
}
return & bcacheCollector {
fs : fs ,
} , nil
}
// Update reads and exposes bcache stats.
// It implements the Collector interface.
func ( c * bcacheCollector ) Update ( ch chan <- prometheus . Metric ) error {
stats , err := c . fs . BcacheStats ( )
if err != nil {
return fmt . Errorf ( "failed to retrieve bcache stats: %v" , err )
}
for _ , s := range stats {
c . updateBcacheStats ( ch , s )
}
return nil
}
type bcacheMetric struct {
name string
desc string
value float64
metricType prometheus . ValueType
extraLabel [ ] string
extraLabelValue string
}
func bcachePeriodStatsToMetric ( ps * bcache . PeriodStats , labelValue string ) [ ] bcacheMetric {
label := [ ] string { "backing_device" }
metrics := [ ] bcacheMetric {
{
name : "bypassed_bytes_total" ,
desc : "Amount of IO (both reads and writes) that has bypassed the cache." ,
value : float64 ( ps . Bypassed ) ,
metricType : prometheus . CounterValue ,
extraLabel : label ,
extraLabelValue : labelValue ,
} ,
{
name : "cache_hits_total" ,
desc : "Hits counted per individual IO as bcache sees them." ,
value : float64 ( ps . CacheHits ) ,
metricType : prometheus . CounterValue ,
extraLabel : label ,
extraLabelValue : labelValue ,
} ,
{
name : "cache_misses_total" ,
desc : "Misses counted per individual IO as bcache sees them." ,
value : float64 ( ps . CacheMisses ) ,
metricType : prometheus . CounterValue ,
extraLabel : label ,
extraLabelValue : labelValue ,
} ,
{
name : "cache_bypass_hits_total" ,
desc : "Hits for IO intended to skip the cache." ,
value : float64 ( ps . CacheBypassHits ) ,
metricType : prometheus . CounterValue ,
extraLabel : label ,
extraLabelValue : labelValue ,
} ,
{
name : "cache_bypass_misses_total" ,
desc : "Misses for IO intended to skip the cache." ,
value : float64 ( ps . CacheBypassMisses ) ,
metricType : prometheus . CounterValue ,
extraLabel : label ,
extraLabelValue : labelValue ,
} ,
{
name : "cache_miss_collisions_total" ,
desc : "Instances where data insertion from cache miss raced with write (data already present)." ,
value : float64 ( ps . CacheMissCollisions ) ,
metricType : prometheus . CounterValue ,
extraLabel : label ,
extraLabelValue : labelValue ,
} ,
{
name : "cache_readaheads_total" ,
desc : "Count of times readahead occurred." ,
value : float64 ( ps . CacheReadaheads ) ,
metricType : prometheus . CounterValue ,
extraLabel : label ,
extraLabelValue : labelValue ,
} ,
}
return metrics
}
// UpdateBcacheStats collects statistics for one bcache ID.
func ( c * bcacheCollector ) updateBcacheStats ( ch chan <- prometheus . Metric , s * bcache . Stats ) {
const (
subsystem = "bcache"
)
var (
devLabel = [ ] string { "uuid" }
allMetrics [ ] bcacheMetric
metrics [ ] bcacheMetric
)
allMetrics = [ ] bcacheMetric {
// metrics in /sys/fs/bcache/<uuid>/
{
name : "average_key_size_sectors" ,
desc : "Average data per key in the btree (sectors)." ,
value : float64 ( s . Bcache . AverageKeySize ) ,
metricType : prometheus . GaugeValue ,
} ,
{
name : "btree_cache_size_bytes" ,
desc : "Amount of memory currently used by the btree cache." ,
value : float64 ( s . Bcache . BtreeCacheSize ) ,
metricType : prometheus . GaugeValue ,
} ,
{
name : "cache_available_percent" ,
desc : "Percentage of cache device without dirty data, useable for writeback (may contain clean cached data)." ,
value : float64 ( s . Bcache . CacheAvailablePercent ) ,
metricType : prometheus . GaugeValue ,
} ,
{
name : "congested" ,
desc : "Congestion." ,
value : float64 ( s . Bcache . Congested ) ,
metricType : prometheus . GaugeValue ,
} ,
{
name : "root_usage_percent" ,
desc : "Percentage of the root btree node in use (tree depth increases if too high)." ,
value : float64 ( s . Bcache . RootUsagePercent ) ,
metricType : prometheus . GaugeValue ,
} ,
{
name : "tree_depth" ,
desc : "Depth of the btree." ,
value : float64 ( s . Bcache . TreeDepth ) ,
metricType : prometheus . GaugeValue ,
} ,
// metrics in /sys/fs/bcache/<uuid>/internal/
{
name : "active_journal_entries" ,
desc : "Number of journal entries that are newer than the index." ,
value : float64 ( s . Bcache . Internal . ActiveJournalEntries ) ,
metricType : prometheus . GaugeValue ,
} ,
{
name : "btree_nodes" ,
desc : "Total nodes in the btree." ,
value : float64 ( s . Bcache . Internal . BtreeNodes ) ,
metricType : prometheus . GaugeValue ,
} ,
{
name : "btree_read_average_duration_seconds" ,
desc : "Average btree read duration." ,
value : float64 ( s . Bcache . Internal . BtreeReadAverageDurationNanoSeconds ) * 1e-9 ,
metricType : prometheus . GaugeValue ,
} ,
{
2018-02-12 18:53:31 +01:00
name : "cache_read_races_total" ,
Add bcache collector (#597)
* Add bcache collector for Linux
This collector gathers metrics related to the Linux block cache
(bcache) from sysfs.
* Removed commented out code
* Use project comment style
* Add _sectors to metric name to indicate unit
* Really use project comment style
* Rename bcache.go to bcache_linux.go
* Keep collector namespace clean
Rename:
- metric -> bcacheMetric
- periodStatsToMetrics -> bcachePeriodStatsToMetric
* Shorten slice initialization
* Change label names to backing_device, cache_device
* Remove five minute metrics (keep only total)
* Include units in additional metric names
* Enable bcache collector by default
* Provide metrics in seconds, not nanoseconds
* remove metrics with label "all"
* Add fixtures, update end-to-end for bcache collector
* Move fixtures/sys into tar.gz
This changeset moves the collector/fixtures/sys directory into
collector/fixtures/sys.tar.gz and tweaks the Makefile to unpack the
tarball before tests are run.
The reason for this change is that Windows does not allow colons in a
path (colons are present in some of the bcache fixture files), nor can
it (out of the box) deal with pathnames longer than 260 characters
(which we would be increasingly likely to hit if we tried to replace
colons with longer codes that are guaranteed not the turn up in regular
file names).
* Add ttar: plain text archive, replacement for tar
This changeset adds ttar, a plain text replacement for tar, and uses it
for the sysfs fixture archive. The syntax is loosely based on tar(1).
Using a plain text archive makes it possible to review changes without
downloading and extracting the archive. Also, when working on the repo,
git diff and git log become useful again, allowing a committer to verify
and track changes over time.
The code is written in bash, because bash is available out of the box on
all major flavors of Linux and on macOS. The feature set used is
restricted to bash version 3.2 because that is what Apple is still
shipping.
The programm also works on Windows if bash is installed. Obviously, it
does not solve the Windows limitations (path length limited to 260
characters, no symbolic links) that prompted the move to an archive
format in the first place.
2017-07-07 07:20:18 +02:00
desc : "Counts instances where while data was being read from the cache, the bucket was reused and invalidated - i.e. where the pointer was stale after the read completed." ,
value : float64 ( s . Bcache . Internal . CacheReadRaces ) ,
metricType : prometheus . CounterValue ,
} ,
}
for _ , bdev := range s . Bdevs {
// metrics in /sys/fs/bcache/<uuid>/<bdev>/
metrics = [ ] bcacheMetric {
{
name : "dirty_data_bytes" ,
desc : "Amount of dirty data for this backing device in the cache." ,
value : float64 ( bdev . DirtyData ) ,
metricType : prometheus . GaugeValue ,
extraLabel : [ ] string { "backing_device" } ,
extraLabelValue : bdev . Name ,
} ,
}
allMetrics = append ( allMetrics , metrics ... )
// metrics in /sys/fs/bcache/<uuid>/<bdev>/stats_total
metrics := bcachePeriodStatsToMetric ( & bdev . Total , bdev . Name )
allMetrics = append ( allMetrics , metrics ... )
}
for _ , cache := range s . Caches {
metrics = [ ] bcacheMetric {
// metrics in /sys/fs/bcache/<uuid>/<cache>/
{
name : "io_errors" ,
desc : "Number of errors that have occurred, decayed by io_error_halflife." ,
value : float64 ( cache . IOErrors ) ,
metricType : prometheus . GaugeValue ,
extraLabel : [ ] string { "cache_device" } ,
extraLabelValue : cache . Name ,
} ,
{
name : "metadata_written_bytes_total" ,
desc : "Sum of all non data writes (btree writes and all other metadata)." ,
value : float64 ( cache . MetadataWritten ) ,
metricType : prometheus . CounterValue ,
extraLabel : [ ] string { "cache_device" } ,
extraLabelValue : cache . Name ,
} ,
{
name : "written_bytes_total" ,
desc : "Sum of all data that has been written to the cache." ,
value : float64 ( cache . Written ) ,
metricType : prometheus . CounterValue ,
extraLabel : [ ] string { "cache_device" } ,
extraLabelValue : cache . Name ,
} ,
// metrics in /sys/fs/bcache/<uuid>/<cache>/priority_stats
{
name : "priority_stats_unused_percent" ,
desc : "The percentage of the cache that doesn't contain any data." ,
value : float64 ( cache . Priority . UnusedPercent ) ,
metricType : prometheus . GaugeValue ,
extraLabel : [ ] string { "cache_device" } ,
extraLabelValue : cache . Name ,
} ,
{
name : "priority_stats_metadata_percent" ,
desc : "Bcache's metadata overhead." ,
value : float64 ( cache . Priority . MetadataPercent ) ,
metricType : prometheus . GaugeValue ,
extraLabel : [ ] string { "cache_device" } ,
extraLabelValue : cache . Name ,
} ,
}
allMetrics = append ( allMetrics , metrics ... )
}
for _ , m := range allMetrics {
labels := append ( devLabel , m . extraLabel ... )
desc := prometheus . NewDesc (
2017-09-28 15:06:26 +02:00
prometheus . BuildFQName ( namespace , subsystem , m . name ) ,
Add bcache collector (#597)
* Add bcache collector for Linux
This collector gathers metrics related to the Linux block cache
(bcache) from sysfs.
* Removed commented out code
* Use project comment style
* Add _sectors to metric name to indicate unit
* Really use project comment style
* Rename bcache.go to bcache_linux.go
* Keep collector namespace clean
Rename:
- metric -> bcacheMetric
- periodStatsToMetrics -> bcachePeriodStatsToMetric
* Shorten slice initialization
* Change label names to backing_device, cache_device
* Remove five minute metrics (keep only total)
* Include units in additional metric names
* Enable bcache collector by default
* Provide metrics in seconds, not nanoseconds
* remove metrics with label "all"
* Add fixtures, update end-to-end for bcache collector
* Move fixtures/sys into tar.gz
This changeset moves the collector/fixtures/sys directory into
collector/fixtures/sys.tar.gz and tweaks the Makefile to unpack the
tarball before tests are run.
The reason for this change is that Windows does not allow colons in a
path (colons are present in some of the bcache fixture files), nor can
it (out of the box) deal with pathnames longer than 260 characters
(which we would be increasingly likely to hit if we tried to replace
colons with longer codes that are guaranteed not the turn up in regular
file names).
* Add ttar: plain text archive, replacement for tar
This changeset adds ttar, a plain text replacement for tar, and uses it
for the sysfs fixture archive. The syntax is loosely based on tar(1).
Using a plain text archive makes it possible to review changes without
downloading and extracting the archive. Also, when working on the repo,
git diff and git log become useful again, allowing a committer to verify
and track changes over time.
The code is written in bash, because bash is available out of the box on
all major flavors of Linux and on macOS. The feature set used is
restricted to bash version 3.2 because that is what Apple is still
shipping.
The programm also works on Windows if bash is installed. Obviously, it
does not solve the Windows limitations (path length limited to 260
characters, no symbolic links) that prompted the move to an archive
format in the first place.
2017-07-07 07:20:18 +02:00
m . desc ,
labels ,
nil ,
)
labelValues := [ ] string { s . Name }
if m . extraLabelValue != "" {
labelValues = append ( labelValues , m . extraLabelValue )
}
ch <- prometheus . MustNewConstMetric (
desc ,
m . metricType ,
m . value ,
labelValues ... ,
)
}
}