ingester: always log CPU samples for CPU limiter

I don't see a reason why we might disable this. The memory footprint is miniscule and the CPU usage is minimal too. The samples give better granularity on what event in the past 60s might have triggered this: "did CPU increase just now or has it been increasing since 30s ago"

Since I think it's harmless, we also don't need a flag for it. The flag is experimental so we can just drop it without notice.

Signed-off-by: Dimitar Dimitrov <[email protected]>

cmd/mimir/config-descriptor.json

@@ -3403,17 +3403,6 @@
           "fieldType": "int",
           "fieldCategory": "experimental"
         },
-        {
-          "kind": "field",
-          "name": "log_utilization_based_limiter_cpu_samples",
-          "required": false,
-          "desc": "Enable logging of utilization based limiter CPU samples.",
-          "fieldValue": null,
-          "fieldDefaultValue": false,
-          "fieldFlag": "ingester.log-utilization-based-limiter-cpu-samples",
-          "fieldType": "boolean",
-          "fieldCategory": "experimental"
-        },
         {
           "kind": "field",
           "name": "error_sample_rate",

cmd/mimir/help-all.txt.tmpl

@@ -1625,8 +1625,6 @@ Usage of ./cmd/mimir/mimir:
     	Max series that this ingester can hold (across all tenants). Requests to create additional series will be rejected. 0 = unlimited.
   -ingester.instance-limits.max-tenants int
     	Max tenants that this ingester can hold. Requests from additional tenants will be rejected. 0 = unlimited.
-  -ingester.log-utilization-based-limiter-cpu-samples
-    	[experimental] Enable logging of utilization based limiter CPU samples.
   -ingester.max-global-exemplars-per-user int
     	[experimental] The maximum number of exemplars in memory, across the cluster. 0 to disable exemplars ingestion.
   -ingester.max-global-metadata-per-metric int

docs/sources/mimir/configure/configuration-parameters/index.md

@@ -1238,10 +1238,6 @@ instance_limits:
 # CLI flag: -ingester.read-path-memory-utilization-limit
 [read_path_memory_utilization_limit: <int> | default = 0]
 
-# (experimental) Enable logging of utilization based limiter CPU samples.
-# CLI flag: -ingester.log-utilization-based-limiter-cpu-samples
-[log_utilization_based_limiter_cpu_samples: <boolean> | default = false]
-
 # (advanced) Each error will be logged once in this many times. Use 0 to log all
 # of them.
 # CLI flag: -ingester.error-sample-rate

pkg/ingester/ingester.go

@@ -198,9 +198,8 @@ type Config struct {
 
 	IgnoreSeriesLimitForMetricNames string `yaml:"ignore_series_limit_for_metric_names" category:"advanced"`
 
-	ReadPathCPUUtilizationLimit          float64 `yaml:"read_path_cpu_utilization_limit" category:"experimental"`
-	ReadPathMemoryUtilizationLimit       uint64  `yaml:"read_path_memory_utilization_limit" category:"experimental"`
-	LogUtilizationBasedLimiterCPUSamples bool    `yaml:"log_utilization_based_limiter_cpu_samples" category:"experimental"`
+	ReadPathCPUUtilizationLimit    float64 `yaml:"read_path_cpu_utilization_limit" category:"experimental"`
+	ReadPathMemoryUtilizationLimit uint64  `yaml:"read_path_memory_utilization_limit" category:"experimental"`
 
 	ErrorSampleRate int64 `yaml:"error_sample_rate" json:"error_sample_rate" category:"advanced"`
 
@@ -238,7 +237,6 @@ func (cfg *Config) RegisterFlags(f *flag.FlagSet, logger log.Logger) {
 	f.StringVar(&cfg.IgnoreSeriesLimitForMetricNames, "ingester.ignore-series-limit-for-metric-names", "", "Comma-separated list of metric names, for which the -ingester.max-global-series-per-metric limit will be ignored. Does not affect the -ingester.max-global-series-per-user limit.")
 	f.Float64Var(&cfg.ReadPathCPUUtilizationLimit, "ingester.read-path-cpu-utilization-limit", 0, "CPU utilization limit, as CPU cores, for CPU/memory utilization based read request limiting. Use 0 to disable it.")
 	f.Uint64Var(&cfg.ReadPathMemoryUtilizationLimit, "ingester.read-path-memory-utilization-limit", 0, "Memory limit, in bytes, for CPU/memory utilization based read request limiting. Use 0 to disable it.")
-	f.BoolVar(&cfg.LogUtilizationBasedLimiterCPUSamples, "ingester.log-utilization-based-limiter-cpu-samples", false, "Enable logging of utilization based limiter CPU samples.")
 	f.Int64Var(&cfg.ErrorSampleRate, "ingester.error-sample-rate", 10, "Each error will be logged once in this many times. Use 0 to log all of them.")
 	f.BoolVar(&cfg.UseIngesterOwnedSeriesForLimits, "ingester.use-ingester-owned-series-for-limits", false, "When enabled, only series currently owned by ingester according to the ring are used when checking user per-tenant series limit.")
 	f.BoolVar(&cfg.UpdateIngesterOwnedSeries, "ingester.track-ingester-owned-series", false, "This option enables tracking of ingester-owned series based on ring state, even if -ingester.use-ingester-owned-series-for-limits is disabled.")
@@ -420,7 +418,7 @@ func New(cfg Config, limits *validation.Overrides, ingestersRing ring.ReadRing,
 
 	if cfg.ReadPathCPUUtilizationLimit > 0 || cfg.ReadPathMemoryUtilizationLimit > 0 {
 		i.utilizationBasedLimiter = limiter.NewUtilizationBasedLimiter(cfg.ReadPathCPUUtilizationLimit,
-			cfg.ReadPathMemoryUtilizationLimit, cfg.LogUtilizationBasedLimiterCPUSamples,
+			cfg.ReadPathMemoryUtilizationLimit, true,
 			log.WithPrefix(logger, "context", "read path"),
 			prometheus.WrapRegistererWithPrefix("cortex_ingester_", registerer))
 	}