Exporter for machine metrics
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// 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.
//go:build (freebsd || dragonfly) && !nomeminfo
// +build freebsd dragonfly
// +build !nomeminfo
package collector
import (
"fmt"
"log/slog"
"github.com/prometheus/client_golang/prometheus"
"golang.org/x/sys/unix"
)
const (
memorySubsystem = "memory"
)
type memoryCollector struct {
pageSize uint64
sysctls []bsdSysctl
kvm kvm
logger *slog.Logger
}
func init() {
registerCollector("meminfo", defaultEnabled, NewMemoryCollector)
}
// NewMemoryCollector returns a new Collector exposing memory stats.
func NewMemoryCollector(logger *slog.Logger) (Collector, error) {
tmp32, err := unix.SysctlUint32("vm.stats.vm.v_page_size")
if err != nil {
return nil, fmt.Errorf("sysctl(vm.stats.vm.v_page_size) failed: %w", err)
}
size := float64(tmp32)
mibSwapTotal := "vm.swap_total"
/* swap_total is FreeBSD specific. Fall back to Dfly specific mib if not present. */
_, err = unix.SysctlUint64(mibSwapTotal)
if err != nil {
mibSwapTotal = "vm.swap_size"
}
fromPage := func(v float64) float64 {
return v * size
}
return &memoryCollector{
logger: logger,
pageSize: uint64(tmp32),
sysctls: []bsdSysctl{
// Descriptions via: https://wiki.freebsd.org/Memory
{
name: "active_bytes",
description: "Recently used by userland",
mib: "vm.stats.vm.v_active_count",
conversion: fromPage,
},
{
name: "inactive_bytes",
description: "Not recently used by userland",
mib: "vm.stats.vm.v_inactive_count",
conversion: fromPage,
},
{
name: "wired_bytes",
description: "Locked in memory by kernel, mlock, etc",
mib: "vm.stats.vm.v_wire_count",
conversion: fromPage,
},
{
name: "user_wired_bytes",
description: "Locked in memory by user, mlock, etc",
mib: "vm.stats.vm.v_user_wire_count",
conversion: fromPage,
dataType: bsdSysctlTypeCLong,
},
{
name: "cache_bytes",
description: "Almost free, backed by swap or files, available for re-allocation",
mib: "vm.stats.vm.v_cache_count",
conversion: fromPage,
},
{
name: "buffer_bytes",
description: "Disk IO Cache entries for non ZFS filesystems, only usable by kernel",
mib: "vfs.bufspace",
dataType: bsdSysctlTypeCLong,
},
{
name: "free_bytes",
description: "Unallocated, available for allocation",
mib: "vm.stats.vm.v_free_count",
conversion: fromPage,
},
{
name: "laundry_bytes",
description: "Dirty not recently used by userland",
mib: "vm.stats.vm.v_laundry_count",
conversion: fromPage,
},
{
name: "size_bytes",
description: "Total physical memory size",
mib: "vm.stats.vm.v_page_count",
conversion: fromPage,
},
{
name: "swap_size_bytes",
description: "Total swap memory size",
mib: mibSwapTotal,
dataType: bsdSysctlTypeUint64,
},
// Descriptions via: top(1)
{
name: "swap_in_bytes_total",
description: "Bytes paged in from swap devices",
mib: "vm.stats.vm.v_swappgsin",
valueType: prometheus.CounterValue,
conversion: fromPage,
},
{
name: "swap_out_bytes_total",
description: "Bytes paged out to swap devices",
mib: "vm.stats.vm.v_swappgsout",
valueType: prometheus.CounterValue,
conversion: fromPage,
},
},
}, nil
}
// Update checks relevant sysctls for current memory usage, and kvm for swap
// usage.
func (c *memoryCollector) Update(ch chan<- prometheus.Metric) error {
for _, m := range c.sysctls {
v, err := m.Value()
if err != nil {
return fmt.Errorf("couldn't get memory: %w", err)
}
// Most are gauges.
if m.valueType == 0 {
m.valueType = prometheus.GaugeValue
}
ch <- prometheus.MustNewConstMetric(
prometheus.NewDesc(
prometheus.BuildFQName(namespace, memorySubsystem, m.name),
m.description,
nil, nil,
), m.valueType, v)
}
swapUsed, err := c.kvm.SwapUsedPages()
if err != nil {
return fmt.Errorf("couldn't get kvm: %w", err)
}
ch <- prometheus.MustNewConstMetric(
prometheus.NewDesc(
prometheus.BuildFQName(namespace, memorySubsystem, "swap_used_bytes"),
"Currently allocated swap",
nil, nil,
), prometheus.GaugeValue, float64(swapUsed*c.pageSize))
return nil
}