collector: add slab info

Co-authored-by: Ben Kochie <superq@gmail.com>
Signed-off-by: Nobuhiro MIKI <nmiki@yahoo-corp.jp>

CHANGELOG.md

@@ -8,6 +8,7 @@
 * [ENHANCEMENT] Add node_softirqs_total metric #2221
 * [ENHANCEMENT] Add device filter flags to arp collector #2254
 * [ENHANCEMENT] Add rapl zone name label option #2401
+* [ENHANCEMENT] Add slabinfo collector #1799
 * [BUGFIX] Sanitize rapl zone names #2299
 
 ## 1.3.1 / 2021-12-01

README.md

@@ -210,6 +210,7 @@ perf | Exposes perf based metrics (Warning: Metrics are dependent on kernel conf
 processes | Exposes aggregate process statistics from `/proc`. | Linux
 qdisc | Exposes [queuing discipline](https://en.wikipedia.org/wiki/Network_scheduler#Linux_kernel) statistics | Linux
 runit | Exposes service status from [runit](http://smarden.org/runit/). | _any_
+slabinfo | Exposes slab statistics from `/proc/slabinfo`. Note that permission of `/proc/slabinfo` is usually 0400, so set it appropriately. | Linux
 supervisord | Exposes service status from [supervisord](http://supervisord.org/). | _any_
 systemd | Exposes service and system status from [systemd](http://www.freedesktop.org/wiki/Software/systemd/). | Linux
 tcpstat | Exposes TCP connection status information from `/proc/net/tcp` and `/proc/net/tcp6`. (Warning: the current version has potential performance issues in high load situations.) | Linux

collector/fixtures/e2e-64k-page-output.txt

@@ -3013,6 +3013,7 @@ node_scrape_collector_success{collector="qdisc"} 1
 node_scrape_collector_success{collector="rapl"} 1
 node_scrape_collector_success{collector="schedstat"} 1
 node_scrape_collector_success{collector="selinux"} 1
+node_scrape_collector_success{collector="slabinfo"} 1
 node_scrape_collector_success{collector="sockstat"} 1
 node_scrape_collector_success{collector="softnet"} 1
 node_scrape_collector_success{collector="stat"} 1
@@ -3029,6 +3030,36 @@ node_scrape_collector_success{collector="zoneinfo"} 1
 # HELP node_selinux_enabled SELinux is enabled, 1 is true, 0 is false
 # TYPE node_selinux_enabled gauge
 node_selinux_enabled 0
+# HELP node_slabinfo_active_objects The number of objects that are currently active (i.e., in use).
+# TYPE node_slabinfo_active_objects gauge
+node_slabinfo_active_objects{slab="dmaengine-unmap-128"} 1206
+node_slabinfo_active_objects{slab="kmalloc-8192"} 132
+node_slabinfo_active_objects{slab="kmem_cache"} 320
+node_slabinfo_active_objects{slab="tw_sock_TCP"} 704
+# HELP node_slabinfo_object_size_bytes The size of objects in this slab, in bytes.
+# TYPE node_slabinfo_object_size_bytes gauge
+node_slabinfo_object_size_bytes{slab="dmaengine-unmap-128"} 1088
+node_slabinfo_object_size_bytes{slab="kmalloc-8192"} 8192
+node_slabinfo_object_size_bytes{slab="kmem_cache"} 256
+node_slabinfo_object_size_bytes{slab="tw_sock_TCP"} 256
+# HELP node_slabinfo_objects The total number of allocated objects (i.e., objects that are both in use and not in use).
+# TYPE node_slabinfo_objects gauge
+node_slabinfo_objects{slab="dmaengine-unmap-128"} 1320
+node_slabinfo_objects{slab="kmalloc-8192"} 148
+node_slabinfo_objects{slab="kmem_cache"} 320
+node_slabinfo_objects{slab="tw_sock_TCP"} 864
+# HELP node_slabinfo_objects_per_slab The number of objects stored in each slab.
+# TYPE node_slabinfo_objects_per_slab gauge
+node_slabinfo_objects_per_slab{slab="dmaengine-unmap-128"} 30
+node_slabinfo_objects_per_slab{slab="kmalloc-8192"} 4
+node_slabinfo_objects_per_slab{slab="kmem_cache"} 32
+node_slabinfo_objects_per_slab{slab="tw_sock_TCP"} 32
+# HELP node_slabinfo_pages_per_slab The number of pages allocated for each slab.
+# TYPE node_slabinfo_pages_per_slab gauge
+node_slabinfo_pages_per_slab{slab="dmaengine-unmap-128"} 8
+node_slabinfo_pages_per_slab{slab="kmalloc-8192"} 8
+node_slabinfo_pages_per_slab{slab="kmem_cache"} 2
+node_slabinfo_pages_per_slab{slab="tw_sock_TCP"} 2
 # HELP node_sockstat_FRAG6_inuse Number of FRAG6 sockets in state inuse.
 # TYPE node_sockstat_FRAG6_inuse gauge
 node_sockstat_FRAG6_inuse 0

collector/fixtures/e2e-output.txt

@@ -3035,6 +3035,7 @@ node_scrape_collector_success{collector="qdisc"} 1
 node_scrape_collector_success{collector="rapl"} 1
 node_scrape_collector_success{collector="schedstat"} 1
 node_scrape_collector_success{collector="selinux"} 1
+node_scrape_collector_success{collector="slabinfo"} 1
 node_scrape_collector_success{collector="sockstat"} 1
 node_scrape_collector_success{collector="softnet"} 1
 node_scrape_collector_success{collector="stat"} 1
@@ -3051,6 +3052,36 @@ node_scrape_collector_success{collector="zoneinfo"} 1
 # HELP node_selinux_enabled SELinux is enabled, 1 is true, 0 is false
 # TYPE node_selinux_enabled gauge
 node_selinux_enabled 0
+# HELP node_slabinfo_active_objects The number of objects that are currently active (i.e., in use).
+# TYPE node_slabinfo_active_objects gauge
+node_slabinfo_active_objects{slab="dmaengine-unmap-128"} 1206
+node_slabinfo_active_objects{slab="kmalloc-8192"} 132
+node_slabinfo_active_objects{slab="kmem_cache"} 320
+node_slabinfo_active_objects{slab="tw_sock_TCP"} 704
+# HELP node_slabinfo_object_size_bytes The size of objects in this slab, in bytes.
+# TYPE node_slabinfo_object_size_bytes gauge
+node_slabinfo_object_size_bytes{slab="dmaengine-unmap-128"} 1088
+node_slabinfo_object_size_bytes{slab="kmalloc-8192"} 8192
+node_slabinfo_object_size_bytes{slab="kmem_cache"} 256
+node_slabinfo_object_size_bytes{slab="tw_sock_TCP"} 256
+# HELP node_slabinfo_objects The total number of allocated objects (i.e., objects that are both in use and not in use).
+# TYPE node_slabinfo_objects gauge
+node_slabinfo_objects{slab="dmaengine-unmap-128"} 1320
+node_slabinfo_objects{slab="kmalloc-8192"} 148
+node_slabinfo_objects{slab="kmem_cache"} 320
+node_slabinfo_objects{slab="tw_sock_TCP"} 864
+# HELP node_slabinfo_objects_per_slab The number of objects stored in each slab.
+# TYPE node_slabinfo_objects_per_slab gauge
+node_slabinfo_objects_per_slab{slab="dmaengine-unmap-128"} 30
+node_slabinfo_objects_per_slab{slab="kmalloc-8192"} 4
+node_slabinfo_objects_per_slab{slab="kmem_cache"} 32
+node_slabinfo_objects_per_slab{slab="tw_sock_TCP"} 32
+# HELP node_slabinfo_pages_per_slab The number of pages allocated for each slab.
+# TYPE node_slabinfo_pages_per_slab gauge
+node_slabinfo_pages_per_slab{slab="dmaengine-unmap-128"} 8
+node_slabinfo_pages_per_slab{slab="kmalloc-8192"} 8
+node_slabinfo_pages_per_slab{slab="kmem_cache"} 2
+node_slabinfo_pages_per_slab{slab="tw_sock_TCP"} 2
 # HELP node_sockstat_FRAG6_inuse Number of FRAG6 sockets in state inuse.
 # TYPE node_sockstat_FRAG6_inuse gauge
 node_sockstat_FRAG6_inuse 0

collector/fixtures/proc/slabinfo

@@ -0,0 +1,6 @@
+slabinfo - version: 2.1
+# name            <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab> : tunables <limit> <batchcount> <sharedfactor> : slabdata <active_slabs> <num_slabs> <sharedavail>
+tw_sock_TCP          704    864    256   32    2 : tunables    0    0    0 : slabdata     27     27      0
+dmaengine-unmap-128   1206   1320   1088   30    8 : tunables    0    0    0 : slabdata     44     44      0
+kmalloc-8192         132    148   8192    4    8 : tunables    0    0    0 : slabdata     37     37      0
+kmem_cache           320    320    256   32    2 : tunables    0    0    0 : slabdata     10     10      0

collector/slabinfo_linux.go

@@ -0,0 +1,121 @@
+// Copyright 2022 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.
+
+//go:build linux && !noslabinfo
+// +build linux,!noslabinfo
+
+package collector
+
+import (
+	"fmt"
+
+	"github.com/go-kit/log"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/procfs"
+)
+
+type slabinfoCollector struct {
+	fs        procfs.FS
+	logger    log.Logger
+	subsystem string
+	labels    []string
+}
+
+func init() {
+	registerCollector("slabinfo", defaultDisabled, NewSlabinfoCollector)
+}
+
+func NewSlabinfoCollector(logger log.Logger) (Collector, error) {
+	fs, err := procfs.NewFS(*procPath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to open procfs: %w", err)
+	}
+
+	return &slabinfoCollector{logger: logger,
+		fs:        fs,
+		subsystem: "slabinfo",
+		labels:    []string{"slab"},
+	}, nil
+}
+
+func (c *slabinfoCollector) Update(ch chan<- prometheus.Metric) error {
+	slabinfo, err := c.fs.SlabInfo()
+	if err != nil {
+		return fmt.Errorf("couldn't get %s: %w", c.subsystem, err)
+	}
+
+	for _, slab := range slabinfo.Slabs {
+		ch <- c.activeObjects(slab.Name, slab.ObjActive)
+		ch <- c.objects(slab.Name, slab.ObjNum)
+		ch <- c.objectSizeBytes(slab.Name, slab.ObjSize)
+		ch <- c.objectsPerSlab(slab.Name, slab.ObjPerSlab)
+		ch <- c.pagesPerSlab(slab.Name, slab.PagesPerSlab)
+	}
+
+	return nil
+}
+
+func (c *slabinfoCollector) activeObjects(label string, val int64) prometheus.Metric {
+	desc := prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, c.subsystem, "active_objects"),
+		"The number of objects that are currently active (i.e., in use).",
+		c.labels, nil)
+
+	return prometheus.MustNewConstMetric(
+		desc, prometheus.GaugeValue, float64(val), label,
+	)
+}
+
+func (c *slabinfoCollector) objects(label string, val int64) prometheus.Metric {
+	desc := prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, c.subsystem, "objects"),
+		"The total number of allocated objects (i.e., objects that are both in use and not in use).",
+		c.labels, nil)
+
+	return prometheus.MustNewConstMetric(
+		desc, prometheus.GaugeValue, float64(val), label,
+	)
+}
+
+func (c *slabinfoCollector) objectSizeBytes(label string, val int64) prometheus.Metric {
+	desc := prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, c.subsystem, "object_size_bytes"),
+		"The size of objects in this slab, in bytes.",
+		c.labels, nil)
+
+	return prometheus.MustNewConstMetric(
+		desc, prometheus.GaugeValue, float64(val), label,
+	)
+}
+
+func (c *slabinfoCollector) objectsPerSlab(label string, val int64) prometheus.Metric {
+	desc := prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, c.subsystem, "objects_per_slab"),
+		"The number of objects stored in each slab.",
+		c.labels, nil)
+
+	return prometheus.MustNewConstMetric(
+		desc, prometheus.GaugeValue, float64(val), label,
+	)
+}
+
+func (c *slabinfoCollector) pagesPerSlab(label string, val int64) prometheus.Metric {
+	desc := prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, c.subsystem, "pages_per_slab"),
+		"The number of pages allocated for each slab.",
+		c.labels, nil)
+
+	return prometheus.MustNewConstMetric(
+		desc, prometheus.GaugeValue, float64(val), label,
+	)
+}

end-to-end-test.sh

@@ -38,6 +38,7 @@ enabled_collectors=$(cat << COLLECTORS
   rapl
   schedstat
   selinux
+  slabinfo
   sockstat
   stat
   thermal_zone