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Merged
kubernetes-prow merged 1 commit into from
Aug 25, 2026
Merged

Add zswap metrics: bytes_used and compression_efficiency #1337

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6 changes: 6 additions & 0 deletions config/system-stats-monitor.json
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Expand Up @@ -94,6 +94,12 @@
},
"memory/percent_used": {
"displayName": "memory/percent_used"
},
"memory/zswap_bytes_used": {
"displayName": "memory/zswap_bytes_used"
},
"memory/zswap_compression_efficiency": {
"displayName": "memory/zswap_compression_efficiency"
}
}
},
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2 changes: 2 additions & 0 deletions pkg/exporters/stackdriver/metric_conversion_test.go
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Expand Up @@ -67,6 +67,8 @@ func TestNPDMetricToSDMetric(t *testing.T) {
{metrics.MemoryPageCacheUsedID, "compute.googleapis.com/guest/memory/page_cache_used", "compute.googleapis.com"},
{metrics.MemoryUnevictableUsedID, "compute.googleapis.com/guest/memory/unevictable_used", "compute.googleapis.com"},
{metrics.MemoryPercentUsedID, "compute.googleapis.com/guest/memory/percent_used", "compute.googleapis.com"},
{metrics.MemoryZswapBytesUsedID, "compute.googleapis.com/guest/memory/zswap/bytes_used", "compute.googleapis.com"},
{metrics.MemoryZswapCompressionEfficiencyID, "compute.googleapis.com/guest/memory/zswap/compression_efficiency", "compute.googleapis.com"},

// Problem metrics
{metrics.ProblemCounterID, "compute.googleapis.com/guest/system/problem_count", "compute.googleapis.com"},
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92 changes: 47 additions & 45 deletions pkg/exporters/stackdriver/stackdriver_exporter.go
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Expand Up @@ -57,51 +57,53 @@ func init() {
const exporterName = "stackdriver"

var NPDMetricToSDMetric = map[metrics.MetricID]string{
metrics.CPURunnableTaskCountID: "compute.googleapis.com/guest/cpu/runnable_task_count",
metrics.CPUUsageTimeID: "compute.googleapis.com/guest/cpu/usage_time",
metrics.CPULoad1m: "compute.googleapis.com/guest/cpu/load_1m",
metrics.CPULoad5m: "compute.googleapis.com/guest/cpu/load_5m",
metrics.CPULoad15m: "compute.googleapis.com/guest/cpu/load_15m",
metrics.DiskAvgQueueLenID: "compute.googleapis.com/guest/disk/queue_length",
metrics.DiskBytesUsedID: "compute.googleapis.com/guest/disk/bytes_used",
metrics.DiskPercentUsedID: "compute.googleapis.com/guest/disk/percent_used",
metrics.DiskIOTimeID: "compute.googleapis.com/guest/disk/io_time",
metrics.DiskMergedOpsCountID: "compute.googleapis.com/guest/disk/merged_operation_count",
metrics.DiskOpsBytesID: "compute.googleapis.com/guest/disk/operation_bytes_count",
metrics.DiskOpsCountID: "compute.googleapis.com/guest/disk/operation_count",
metrics.DiskOpsTimeID: "compute.googleapis.com/guest/disk/operation_time",
metrics.DiskWeightedIOID: "compute.googleapis.com/guest/disk/weighted_io_time",
metrics.HostUptimeID: "compute.googleapis.com/guest/system/uptime",
metrics.MemoryAnonymousUsedID: "compute.googleapis.com/guest/memory/anonymous_used",
metrics.MemoryBytesUsedID: "compute.googleapis.com/guest/memory/bytes_used",
metrics.MemoryDirtyUsedID: "compute.googleapis.com/guest/memory/dirty_used",
metrics.MemoryPageCacheUsedID: "compute.googleapis.com/guest/memory/page_cache_used",
metrics.MemoryUnevictableUsedID: "compute.googleapis.com/guest/memory/unevictable_used",
metrics.MemoryPercentUsedID: "compute.googleapis.com/guest/memory/percent_used",
metrics.ProblemCounterID: "compute.googleapis.com/guest/system/problem_count",
metrics.ProblemGaugeID: "compute.googleapis.com/guest/system/problem_state",
metrics.OSFeatureID: "compute.googleapis.com/guest/system/os_feature_enabled",
metrics.SystemProcessesTotal: "kubernetes.io/internal/node/guest/system/processes_total",
metrics.SystemProcsRunning: "kubernetes.io/internal/node/guest/system/procs_running",
metrics.SystemProcsBlocked: "kubernetes.io/internal/node/guest/system/procs_blocked",
metrics.SystemInterruptsTotal: "kubernetes.io/internal/node/guest/system/interrupts_total",
metrics.SystemCPUStat: "kubernetes.io/internal/node/guest/system/cpu_stat",
metrics.NetDevRxBytes: "kubernetes.io/internal/node/guest/net/rx_bytes",
metrics.NetDevRxPackets: "kubernetes.io/internal/node/guest/net/rx_packets",
metrics.NetDevRxErrors: "kubernetes.io/internal/node/guest/net/rx_errors",
metrics.NetDevRxDropped: "kubernetes.io/internal/node/guest/net/rx_dropped",
metrics.NetDevRxFifo: "kubernetes.io/internal/node/guest/net/rx_fifo",
metrics.NetDevRxFrame: "kubernetes.io/internal/node/guest/net/rx_frame",
metrics.NetDevRxCompressed: "kubernetes.io/internal/node/guest/net/rx_compressed",
metrics.NetDevRxMulticast: "kubernetes.io/internal/node/guest/net/rx_multicast",
metrics.NetDevTxBytes: "kubernetes.io/internal/node/guest/net/tx_bytes",
metrics.NetDevTxPackets: "kubernetes.io/internal/node/guest/net/tx_packets",
metrics.NetDevTxErrors: "kubernetes.io/internal/node/guest/net/tx_errors",
metrics.NetDevTxDropped: "kubernetes.io/internal/node/guest/net/tx_dropped",
metrics.NetDevTxFifo: "kubernetes.io/internal/node/guest/net/tx_fifo",
metrics.NetDevTxCollisions: "kubernetes.io/internal/node/guest/net/tx_collisions",
metrics.NetDevTxCarrier: "kubernetes.io/internal/node/guest/net/tx_carrier",
metrics.NetDevTxCompressed: "kubernetes.io/internal/node/guest/net/tx_compressed",
metrics.CPURunnableTaskCountID: "compute.googleapis.com/guest/cpu/runnable_task_count",
metrics.CPUUsageTimeID: "compute.googleapis.com/guest/cpu/usage_time",
metrics.CPULoad1m: "compute.googleapis.com/guest/cpu/load_1m",
metrics.CPULoad5m: "compute.googleapis.com/guest/cpu/load_5m",
metrics.CPULoad15m: "compute.googleapis.com/guest/cpu/load_15m",
metrics.DiskAvgQueueLenID: "compute.googleapis.com/guest/disk/queue_length",
metrics.DiskBytesUsedID: "compute.googleapis.com/guest/disk/bytes_used",
metrics.DiskPercentUsedID: "compute.googleapis.com/guest/disk/percent_used",
metrics.DiskIOTimeID: "compute.googleapis.com/guest/disk/io_time",
metrics.DiskMergedOpsCountID: "compute.googleapis.com/guest/disk/merged_operation_count",
metrics.DiskOpsBytesID: "compute.googleapis.com/guest/disk/operation_bytes_count",
metrics.DiskOpsCountID: "compute.googleapis.com/guest/disk/operation_count",
metrics.DiskOpsTimeID: "compute.googleapis.com/guest/disk/operation_time",
metrics.DiskWeightedIOID: "compute.googleapis.com/guest/disk/weighted_io_time",
metrics.HostUptimeID: "compute.googleapis.com/guest/system/uptime",
metrics.MemoryAnonymousUsedID: "compute.googleapis.com/guest/memory/anonymous_used",
metrics.MemoryBytesUsedID: "compute.googleapis.com/guest/memory/bytes_used",
metrics.MemoryDirtyUsedID: "compute.googleapis.com/guest/memory/dirty_used",
metrics.MemoryPageCacheUsedID: "compute.googleapis.com/guest/memory/page_cache_used",
metrics.MemoryUnevictableUsedID: "compute.googleapis.com/guest/memory/unevictable_used",
metrics.MemoryPercentUsedID: "compute.googleapis.com/guest/memory/percent_used",
metrics.MemoryZswapBytesUsedID: "compute.googleapis.com/guest/memory/zswap/bytes_used",
metrics.MemoryZswapCompressionEfficiencyID: "compute.googleapis.com/guest/memory/zswap/compression_efficiency",
Comment on lines +81 to +82

@DigitalVeer DigitalVeer Aug 25, 2026

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Is this metric registered and/or launched? I cannot find any documentation and some issues came up when testing locally.

  1. CreateTimeSeries rejected on both spellings:
control  guest/memory/percent_used            → {}  (accepted)
PR type  guest/memory/zswap/bytes_used        → 400 INVALID_ARGUMENT "unknown metric type"
flat     guest/memory/zswap_bytes_used        → 400 INVALID_ARGUMENT "unknown metric type"
  1. Not in the API descriptors:
$ GET /v3/projects/…/metricDescriptors?filter=starts_with("compute.googleapis.com/guest")
-- No match for zswap
  1. Running on stackdriver fails on every export:
… metric.type="compute.googleapis.com/guest/memory/zswap/compression_efficiency" … unknown metric type
… metric.type="compute.googleapis.com/guest/memory/zswap/bytes_used" … unknown metric type

@divikchotani-oss divikchotani-oss Aug 25, 2026

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Hi, thanks for the catch! I updated the documentation, the reason for the error is because the metric descriptors have not yet been registered in the backend, once that happens, the errors should be resolved.

metrics.ProblemCounterID: "compute.googleapis.com/guest/system/problem_count",
metrics.ProblemGaugeID: "compute.googleapis.com/guest/system/problem_state",
metrics.OSFeatureID: "compute.googleapis.com/guest/system/os_feature_enabled",
metrics.SystemProcessesTotal: "kubernetes.io/internal/node/guest/system/processes_total",
metrics.SystemProcsRunning: "kubernetes.io/internal/node/guest/system/procs_running",
metrics.SystemProcsBlocked: "kubernetes.io/internal/node/guest/system/procs_blocked",
metrics.SystemInterruptsTotal: "kubernetes.io/internal/node/guest/system/interrupts_total",
metrics.SystemCPUStat: "kubernetes.io/internal/node/guest/system/cpu_stat",
metrics.NetDevRxBytes: "kubernetes.io/internal/node/guest/net/rx_bytes",
metrics.NetDevRxPackets: "kubernetes.io/internal/node/guest/net/rx_packets",
metrics.NetDevRxErrors: "kubernetes.io/internal/node/guest/net/rx_errors",
metrics.NetDevRxDropped: "kubernetes.io/internal/node/guest/net/rx_dropped",
metrics.NetDevRxFifo: "kubernetes.io/internal/node/guest/net/rx_fifo",
metrics.NetDevRxFrame: "kubernetes.io/internal/node/guest/net/rx_frame",
metrics.NetDevRxCompressed: "kubernetes.io/internal/node/guest/net/rx_compressed",
metrics.NetDevRxMulticast: "kubernetes.io/internal/node/guest/net/rx_multicast",
metrics.NetDevTxBytes: "kubernetes.io/internal/node/guest/net/tx_bytes",
metrics.NetDevTxPackets: "kubernetes.io/internal/node/guest/net/tx_packets",
metrics.NetDevTxErrors: "kubernetes.io/internal/node/guest/net/tx_errors",
metrics.NetDevTxDropped: "kubernetes.io/internal/node/guest/net/tx_dropped",
metrics.NetDevTxFifo: "kubernetes.io/internal/node/guest/net/tx_fifo",
metrics.NetDevTxCollisions: "kubernetes.io/internal/node/guest/net/tx_collisions",
metrics.NetDevTxCarrier: "kubernetes.io/internal/node/guest/net/tx_carrier",
metrics.NetDevTxCompressed: "kubernetes.io/internal/node/guest/net/tx_compressed",
}

func getMetricTypeConversionFunction(customMetricPrefix string) func(string) string {
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2 changes: 2 additions & 0 deletions pkg/systemstatsmonitor/README.md
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Expand Up @@ -77,6 +77,8 @@ Below metrics are collected from `memory` component:
* `memory_page_cache_used`: Page cache memory usage, in Bytes. Memory usage state is reported under the `state` metric label (e.g. `active`, `inactive`). `active` means the memory has been used more recently and usually not reclaimed until needed. Summing values of all states yields the total page cache memory used.
* `memory_unevictable_used`: [Unevictable memory][/proc doc] usage, in Bytes.
* `memory_dirty_used`: Dirty pages usage, in Bytes. Memory usage state is reported under the `state` metric label (e.g. `dirty`, `writeback`). `dirty` means the memory is waiting to be written back to disk, and `writeback` means the memory is actively being written back to disk.
* `memory_zswap_bytes_used`: Zswap memory usage, in Bytes. Collected from `/proc/meminfo` (`Zswap`).
* `memory_zswap_compression_efficiency`: Zswap compression efficiency ratio (`Zswapped` / `Zswap`).

### OS features

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39 changes: 33 additions & 6 deletions pkg/systemstatsmonitor/memory_collector.go
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Expand Up @@ -24,12 +24,14 @@ import (
)

type memoryCollector struct {
mBytesUsed *metrics.Int64Metric
mPercentUsed *metrics.Float64Metric
mAnonymousUsed *metrics.Int64Metric
mPageCacheUsed *metrics.Int64Metric
mUnevictableUsed *metrics.Int64Metric
mDirtyUsed *metrics.Int64Metric
mBytesUsed *metrics.Int64Metric
mPercentUsed *metrics.Float64Metric
mAnonymousUsed *metrics.Int64Metric
mPageCacheUsed *metrics.Int64Metric
mUnevictableUsed *metrics.Int64Metric
mDirtyUsed *metrics.Int64Metric
mZswapBytesUsed *metrics.Int64Metric
mZswapCompressionEfficiency *metrics.Float64Metric

config *ssmtypes.MemoryStatsConfig
}
Expand Down Expand Up @@ -105,5 +107,30 @@ func NewMemoryCollectorOrDie(memoryConfig *ssmtypes.MemoryStatsConfig) *memoryCo
klog.Fatalf("Error initializing metric for %q: %v", metrics.MemoryDirtyUsedID, err)
}

if _, ok := memoryConfig.MetricsConfigs[string(metrics.MemoryZswapBytesUsedID)]; ok {

@wangzhen127 wangzhen127 Aug 21, 2026

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Can you add some unit test?

@wangzhen127 wangzhen127 Aug 21, 2026

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and can you squash the commits after the update?

@divikchotani-oss divikchotani-oss Aug 21, 2026

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I added unit tests for zswap to the commit and squashed it all into one commit, thanks

mc.mZswapBytesUsed, err = metrics.NewInt64Metric(
metrics.MemoryZswapBytesUsedID,
memoryConfig.MetricsConfigs[string(metrics.MemoryZswapBytesUsedID)].DisplayName,
"Zswap usage in bytes",
"Byte",
metrics.LastValue,
[]string{})
if err != nil {
klog.Fatalf("Error initializing metric for %q: %v", metrics.MemoryZswapBytesUsedID, err)
}
}
if _, ok := memoryConfig.MetricsConfigs[string(metrics.MemoryZswapCompressionEfficiencyID)]; ok {
mc.mZswapCompressionEfficiency, err = metrics.NewFloat64Metric(
metrics.MemoryZswapCompressionEfficiencyID,
memoryConfig.MetricsConfigs[string(metrics.MemoryZswapCompressionEfficiencyID)].DisplayName,
"Zswap compression efficiency ratio (uncompressed/compressed)",
"1",
metrics.LastValue,
[]string{})
if err != nil {
klog.Fatalf("Error initializing metric for %q: %v", metrics.MemoryZswapCompressionEfficiencyID, err)
}
}

return &mc
}
38 changes: 38 additions & 0 deletions pkg/systemstatsmonitor/memory_collector_test.go
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Expand Up @@ -17,12 +17,50 @@ limitations under the License.
package systemstatsmonitor

import (
"encoding/json"
"testing"

"github.com/stretchr/testify/assert"

ssmtypes "k8s.io/node-problem-detector/pkg/systemstatsmonitor/types"
)

const (
fakeZswapConfig = `
{
"metricsConfigs": {
"memory/zswap_bytes_used": {
"displayName": "memory/zswap_bytes_used"
},
"memory/zswap_compression_efficiency": {
"displayName": "memory/zswap_compression_efficiency"
}
}
}
`
)

func TestMemoryCollector(t *testing.T) {
// Original test
mc := NewMemoryCollectorOrDie(&ssmtypes.MemoryStatsConfig{})
mc.collect()

// Ensure zswap metrics are nil when not in config
assert.Nil(t, mc.mZswapBytesUsed)
assert.Nil(t, mc.mZswapCompressionEfficiency)
}

func TestMemoryCollectorZswap(t *testing.T) {
cfg := &ssmtypes.MemoryStatsConfig{}
if err := json.Unmarshal([]byte(fakeZswapConfig), cfg); err != nil {
t.Fatalf("cannot load memory config: %s", err)
}

mc := NewMemoryCollectorOrDie(cfg)

// Ensure zswap metrics are initialized when in config
assert.NotNil(t, mc.mZswapBytesUsed)
assert.NotNil(t, mc.mZswapCompressionEfficiency)

mc.collect()
}
20 changes: 20 additions & 0 deletions pkg/systemstatsmonitor/memory_collector_unix.go
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Expand Up @@ -120,4 +120,24 @@ func (mc *memoryCollector) collect() {
klog.Errorf("Failed to record unevictable used memory: %v", err)
}
}

if mc.mZswapBytesUsed != nil {
var bytesUsed int64
if meminfo.Zswap != nil && *meminfo.Zswap > 0 {
bytesUsed = int64(*meminfo.Zswap) * 1024 // kB -> B
}
if err := mc.mZswapBytesUsed.Record(map[string]string{}, bytesUsed); err != nil {
klog.Errorf("Failed to record zswap bytes used: %v", err)
}
}

if mc.mZswapCompressionEfficiency != nil {
var efficiency float64
if meminfo.Zswap != nil && *meminfo.Zswap > 0 && meminfo.Zswapped != nil {
efficiency = float64(*meminfo.Zswapped) / float64(*meminfo.Zswap)
}
if err := mc.mZswapCompressionEfficiency.Record(map[string]string{}, efficiency); err != nil {
klog.Errorf("Failed to record zswap compression efficiency: %v", err)
}
}
}
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