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Merged
SuperQ merged 1 commit into from
Aug 5, 2026
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ksmd: Improve help text #3782

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20 changes: 10 additions & 10 deletions collector/fixtures/e2e-64k-page-output.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -1987,34 +1987,34 @@ node_ipvs_outgoing_packets_total 0
# HELP node_kernel_hung_tasks_total Total number of tasks that have been detected as hung since the system booted.
# TYPE node_kernel_hung_tasks_total counter
node_kernel_hung_tasks_total 42
# HELP node_ksmd_full_scans_total ksmd 'full_scans' file.
# HELP node_ksmd_full_scans_total How many times all mergeable areas have been scanned.
# TYPE node_ksmd_full_scans_total counter
node_ksmd_full_scans_total 323
# HELP node_ksmd_general_profit_bytes ksmd 'general_profit' file.
# HELP node_ksmd_general_profit_bytes How effective is KSM. ksm_saved_pages * sizeof(page) - (all_rmap_items) * sizeof(rmap_item)
# TYPE node_ksmd_general_profit_bytes gauge
node_ksmd_general_profit_bytes 1.04448e+06
# HELP node_ksmd_merge_across_nodes ksmd 'merge_across_nodes' file.
# HELP node_ksmd_merge_across_nodes Specifies if pages from different NUMA nodes can be merged.
# TYPE node_ksmd_merge_across_nodes gauge
node_ksmd_merge_across_nodes 1
# HELP node_ksmd_pages_shared ksmd 'pages_shared' file.
# HELP node_ksmd_pages_shared How many shared pages are being used.
# TYPE node_ksmd_pages_shared gauge
node_ksmd_pages_shared 1
# HELP node_ksmd_pages_sharing ksmd 'pages_sharing' file.
# HELP node_ksmd_pages_sharing How many more sites are sharing them i.e. how much saved.
# TYPE node_ksmd_pages_sharing gauge
node_ksmd_pages_sharing 255
# HELP node_ksmd_pages_to_scan ksmd 'pages_to_scan' file.
# HELP node_ksmd_pages_to_scan How many pages to scan before ksmd goes to sleep.
# TYPE node_ksmd_pages_to_scan gauge
node_ksmd_pages_to_scan 100
# HELP node_ksmd_pages_unshared ksmd 'pages_unshared' file.
# HELP node_ksmd_pages_unshared How many pages unique but repeatedly checked for merging.
# TYPE node_ksmd_pages_unshared gauge
node_ksmd_pages_unshared 0
# HELP node_ksmd_pages_volatile ksmd 'pages_volatile' file.
# HELP node_ksmd_pages_volatile How many pages changing too fast to be placed in a tree.
# TYPE node_ksmd_pages_volatile gauge
node_ksmd_pages_volatile 0
# HELP node_ksmd_run ksmd 'run' file.
# HELP node_ksmd_run The status of ksmd. stopped = 0, running = 1
# TYPE node_ksmd_run gauge
node_ksmd_run 1
# HELP node_ksmd_sleep_seconds ksmd 'sleep_millisecs' file.
# HELP node_ksmd_sleep_seconds How many seconds ksmd should sleep before next scan.
# TYPE node_ksmd_sleep_seconds gauge
node_ksmd_sleep_seconds 0.02
# HELP node_lnstat_allocs_total linux network cache stats
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20 changes: 10 additions & 10 deletions collector/fixtures/e2e-output.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -2019,34 +2019,34 @@ node_ipvs_outgoing_packets_total 0
# HELP node_kernel_hung_tasks_total Total number of tasks that have been detected as hung since the system booted.
# TYPE node_kernel_hung_tasks_total counter
node_kernel_hung_tasks_total 42
# HELP node_ksmd_full_scans_total ksmd 'full_scans' file.
# HELP node_ksmd_full_scans_total How many times all mergeable areas have been scanned.
# TYPE node_ksmd_full_scans_total counter
node_ksmd_full_scans_total 323
# HELP node_ksmd_general_profit_bytes ksmd 'general_profit' file.
# HELP node_ksmd_general_profit_bytes How effective is KSM. ksm_saved_pages * sizeof(page) - (all_rmap_items) * sizeof(rmap_item)
# TYPE node_ksmd_general_profit_bytes gauge
node_ksmd_general_profit_bytes 1.04448e+06
# HELP node_ksmd_merge_across_nodes ksmd 'merge_across_nodes' file.
# HELP node_ksmd_merge_across_nodes Specifies if pages from different NUMA nodes can be merged.
# TYPE node_ksmd_merge_across_nodes gauge
node_ksmd_merge_across_nodes 1
# HELP node_ksmd_pages_shared ksmd 'pages_shared' file.
# HELP node_ksmd_pages_shared How many shared pages are being used.
# TYPE node_ksmd_pages_shared gauge
node_ksmd_pages_shared 1
# HELP node_ksmd_pages_sharing ksmd 'pages_sharing' file.
# HELP node_ksmd_pages_sharing How many more sites are sharing them i.e. how much saved.
# TYPE node_ksmd_pages_sharing gauge
node_ksmd_pages_sharing 255
# HELP node_ksmd_pages_to_scan ksmd 'pages_to_scan' file.
# HELP node_ksmd_pages_to_scan How many pages to scan before ksmd goes to sleep.
# TYPE node_ksmd_pages_to_scan gauge
node_ksmd_pages_to_scan 100
# HELP node_ksmd_pages_unshared ksmd 'pages_unshared' file.
# HELP node_ksmd_pages_unshared How many pages unique but repeatedly checked for merging.
# TYPE node_ksmd_pages_unshared gauge
node_ksmd_pages_unshared 0
# HELP node_ksmd_pages_volatile ksmd 'pages_volatile' file.
# HELP node_ksmd_pages_volatile How many pages changing too fast to be placed in a tree.
# TYPE node_ksmd_pages_volatile gauge
node_ksmd_pages_volatile 0
# HELP node_ksmd_run ksmd 'run' file.
# HELP node_ksmd_run The status of ksmd. stopped = 0, running = 1
# TYPE node_ksmd_run gauge
node_ksmd_run 1
# HELP node_ksmd_sleep_seconds ksmd 'sleep_millisecs' file.
# HELP node_ksmd_sleep_seconds How many seconds ksmd should sleep before next scan.
# TYPE node_ksmd_sleep_seconds gauge
node_ksmd_sleep_seconds 0.02
# HELP node_lnstat_allocs_total linux network cache stats
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122 changes: 88 additions & 34 deletions collector/ksmd_linux.go
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
// Copyright 2015 The Prometheus Authors
// Copyright 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
Expand All @@ -17,53 +17,93 @@ package collector

import (
"errors"
"fmt"
"log/slog"
"os"
"path/filepath"

"github.com/prometheus/client_golang/prometheus"
)

const ksmdCollectorSubsystem = "ksmd"

var (
ksmdFiles = []string{"full_scans", "general_profit", "merge_across_nodes", "pages_shared",
"pages_sharing", "pages_to_scan", "pages_unshared", "pages_volatile", "run",
"sleep_millisecs"}
ksmdFiles = []string{
"full_scans",
"general_profit",
"merge_across_nodes",
"pages_shared",
"pages_sharing",
"pages_to_scan",
"pages_unshared",
"pages_volatile",
"run",
"sleep_millisecs",
}

// Help text from https://docs.kernel.org/admin-guide/mm/ksm.html
ksmdFullScansDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, ksmdCollectorSubsystem, "full_scans_total"),
"How many times all mergeable areas have been scanned.",
nil, nil,
)
ksmdGeneralProfitDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, ksmdCollectorSubsystem, "general_profit_bytes"),
"How effective is KSM. ksm_saved_pages * sizeof(page) - (all_rmap_items) * sizeof(rmap_item)",
nil, nil,
)
ksmdMergeAcrossNodesDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, ksmdCollectorSubsystem, "merge_across_nodes"),
"Specifies if pages from different NUMA nodes can be merged.",
nil, nil,
)
ksmdPagesSharedDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, ksmdCollectorSubsystem, "pages_shared"),
"How many shared pages are being used.",
nil, nil,
)
ksmdPagesSharingDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, ksmdCollectorSubsystem, "pages_sharing"),
"How many more sites are sharing them i.e. how much saved.",
nil, nil,
)
ksmdPagesToScanDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, ksmdCollectorSubsystem, "pages_to_scan"),
"How many pages to scan before ksmd goes to sleep.",
nil, nil,
)
ksmdPagesUnsharedDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, ksmdCollectorSubsystem, "pages_unshared"),
"How many pages unique but repeatedly checked for merging.",
nil, nil,
)
ksmdPagesVolatileDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, ksmdCollectorSubsystem, "pages_volatile"),
"How many pages changing too fast to be placed in a tree.",
nil, nil,
)
ksmdRunDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, ksmdCollectorSubsystem, "run"),
"The status of ksmd. stopped = 0, running = 1",
nil, nil,
)
ksmdSleepSecondsDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, ksmdCollectorSubsystem, "sleep_seconds"),
"How many seconds ksmd should sleep before next scan.",
nil, nil,
)
)

type ksmdCollector struct {
metricDescs map[string]*prometheus.Desc
logger *slog.Logger
logger *slog.Logger
}

func init() {
registerCollector("ksmd", defaultDisabled, NewKsmdCollector)
}

func getCanonicalMetricName(filename string) string {
switch filename {
case "full_scans":
return filename + "_total"
case "general_profit":
return "general_profit_bytes"
case "sleep_millisecs":
return "sleep_seconds"
default:
return filename
}
registerCollector(ksmdCollectorSubsystem, defaultDisabled, NewKsmdCollector)
}

// NewKsmdCollector returns a new Collector exposing kernel/system statistics.
func NewKsmdCollector(logger *slog.Logger) (Collector, error) {
subsystem := "ksmd"
descs := make(map[string]*prometheus.Desc)

for _, n := range ksmdFiles {
descs[n] = prometheus.NewDesc(
prometheus.BuildFQName(namespace, subsystem, getCanonicalMetricName(n)),
fmt.Sprintf("ksmd '%s' file.", n), nil, nil)
}
return &ksmdCollector{descs, logger}, nil
return &ksmdCollector{logger: logger}, nil
}

// Update implements Collector and exposes kernel and system statistics.
Expand All @@ -78,15 +118,29 @@ func (c *ksmdCollector) Update(ch chan<- prometheus.Metric) error {
return err
}

t := prometheus.GaugeValue
v := float64(val)
switch n {
case "full_scans":
t = prometheus.CounterValue
ch <- prometheus.MustNewConstMetric(ksmdFullScansDesc, prometheus.CounterValue, v)
case "general_profit":
ch <- prometheus.MustNewConstMetric(ksmdGeneralProfitDesc, prometheus.GaugeValue, v)
case "merge_across_nodes":
ch <- prometheus.MustNewConstMetric(ksmdMergeAcrossNodesDesc, prometheus.GaugeValue, v)
case "pages_shared":
ch <- prometheus.MustNewConstMetric(ksmdPagesSharedDesc, prometheus.GaugeValue, v)
case "pages_sharing":
ch <- prometheus.MustNewConstMetric(ksmdPagesSharingDesc, prometheus.GaugeValue, v)
case "pages_to_scan":
ch <- prometheus.MustNewConstMetric(ksmdPagesToScanDesc, prometheus.GaugeValue, v)
case "pages_unshared":
ch <- prometheus.MustNewConstMetric(ksmdPagesUnsharedDesc, prometheus.GaugeValue, v)
case "pages_volatile":
ch <- prometheus.MustNewConstMetric(ksmdPagesVolatileDesc, prometheus.GaugeValue, v)
case "run":
ch <- prometheus.MustNewConstMetric(ksmdRunDesc, prometheus.GaugeValue, v)
case "sleep_millisecs":
v /= 1000
ch <- prometheus.MustNewConstMetric(ksmdSleepSecondsDesc, prometheus.GaugeValue, v/1000)
}
ch <- prometheus.MustNewConstMetric(c.metricDescs[n], t, v)
}

return nil
Expand Down
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