Fix exception-threshold-bump when restoring lost headroom

[rdesgroppes]

What does this PR do?

Fix fetch_main_headroom() in tasks/static_quality_gates/metrics.py: widen its lookback from 1 day to 7 so it doesn't miss main's last report over a weekend, and floor the computed headroom at BUFFER_SIZE instead of 0 when main is already over its own limit.

Motivation

agent_rpm_arm64/agent_suse_arm64 exceeded their 735.07 MiB limit on main, driven mainly by #54204's Rust data-security check (+3.49 MiB).
Restoring headroom via quality-gates.exception-threshold-bump should have been a one-line fix, but the script failed to produce a usable threshold, for two reasons:

1. its 1-day lookback missed main's last report across the weekend gap between Friday's merges and the incident, since main only reports this metric when a commit lands,
2. it sets the new limit to the PR's own reported size plus main's headroom, so whenever main's headroom was at or below 0 (as it was here) the new limit collapsed to just the PR's own size: a threshold still below main's actual usage, one that would not even have unblocked main.

Describe how you validated your changes

Added test_headroom_floored_when_main_over_its_own_limit (renamed from the now-inverted test_headroom_never_negative) asserting the floor applies when main is over budget.

Reran quality-gates.exception-threshold-bump twice independently: both runs produced identical thresholds, confirming the fix is deterministic.

[dd-octo-sts]

Files inventory check summary

File checks results against ancestor e98625f8:

Results for datadog-agent_7.84.0~devel.git.36.843f65f.pipeline.129910554-1_amd64.deb:

No change detected

Results for datadog-iot-agent_7.84.0~devel.git.36.843f65f.pipeline.129910554-1_amd64.deb:

No change detected

[dd-octo-sts]

Static quality checks

✅ Please find below the results from static quality gates
Comparison made with ancestor e98625f
📊 Static Quality Gates Dashboard
🔗 SQG Job

32 successful checks with minimal change (< 2 KiB)

	Quality gate	Current Size
✅	agent_deb_amd64	759.551 MiB
✅	agent_deb_amd64_fips	712.889 MiB
✅	agent_heroku_amd64	312.284 MiB
✅	agent_rpm_amd64	759.535 MiB
✅	agent_rpm_amd64_fips	712.873 MiB
✅	agent_rpm_arm64	735.491 MiB
✅	agent_rpm_arm64_fips	692.104 MiB
✅	agent_suse_amd64	759.535 MiB
✅	agent_suse_amd64_fips	712.873 MiB
✅	agent_suse_arm64	735.491 MiB
✅	agent_suse_arm64_fips	692.104 MiB
✅	docker_agent_amd64	818.162 MiB
✅	docker_agent_arm64	819.163 MiB
✅	docker_agent_jmx_amd64	1009.060 MiB
✅	docker_agent_jmx_arm64	998.713 MiB
✅	docker_cluster_agent_amd64	210.227 MiB
✅	docker_cluster_agent_arm64	223.267 MiB
✅	docker_cws_instrumentation_amd64	7.439 MiB
✅	docker_cws_instrumentation_arm64	6.877 MiB
✅	docker_dogstatsd_amd64	39.479 MiB
✅	docker_dogstatsd_arm64	37.560 MiB
✅	docker_host_profiler_amd64	305.801 MiB
✅	docker_host_profiler_arm64	317.116 MiB
✅	dogstatsd_deb_amd64	30.220 MiB
✅	dogstatsd_deb_arm64	28.243 MiB
✅	dogstatsd_rpm_amd64	30.220 MiB
✅	dogstatsd_suse_amd64	30.220 MiB
✅	iot_agent_deb_amd64	46.431 MiB
✅	iot_agent_deb_arm64	43.103 MiB
✅	iot_agent_deb_armhf	43.883 MiB
✅	iot_agent_rpm_amd64	46.432 MiB
✅	iot_agent_suse_amd64	46.431 MiB

[cit-pr-commenter-54b7da]

Regression Detector

Regression Detector Results

Metrics dashboard
Target profiles
Run ID: 572dd0cd-a3ec-4e6b-9a49-85ccdc17697c

Baseline: 0a076ce
Comparison: 1d86ce7
Diff

Optimization Goals: ✅ No significant changes detected

Fine details of change detection per experiment

perf	experiment	goal	Δ mean %	Δ mean % CI	trials	links
➖	quality_gate_logs	% cpu utilization	+1.67	[+0.82, +2.51]	1	Logs bounds checks dashboard
➖	quality_gate_idle	memory utilization	+0.12	[+0.07, +0.16]	1	Logs bounds checks dashboard
➖	quality_gate_security_mean_fs_load	memory utilization	+0.07	[+0.04, +0.11]	1	Logs bounds checks dashboard
➖	quality_gate_metrics_logs	memory utilization	+0.03	[-0.22, +0.27]	1	Logs bounds checks dashboard
➖	quality_gate_security_no_fs_load	memory utilization	-0.03	[-0.12, +0.07]	1	Logs bounds checks dashboard
➖	quality_gate_private_action_runner	memory utilization	-0.10	[-0.22, +0.02]	1	Logs bounds checks dashboard
➖	quality_gate_idle_all_features	memory utilization	-0.22	[-0.26, -0.18]	1	Logs bounds checks dashboard
➖	quality_gate_security_idle	memory utilization	-0.25	[-0.31, -0.19]	1	Logs bounds checks dashboard

Bounds Checks: ✅ Passed

perf	experiment	bounds_check_name	replicates_passed	observed_value	links
✅	quality_gate_idle	intake_connections	10/10	3 ≤ 4	bounds checks dashboard
✅	quality_gate_idle	memory_usage	10/10	149.10MiB ≤ 154MiB	bounds checks dashboard
✅	quality_gate_idle	total_bytes_received	10/10	734.02KiB ≤ 819.20KiB	bounds checks dashboard
✅	quality_gate_idle_all_features	intake_connections	10/10	3 ≤ 4	bounds checks dashboard
✅	quality_gate_idle_all_features	memory_usage	10/10	488.95MiB ≤ 512MiB	bounds checks dashboard
✅	quality_gate_idle_all_features	total_bytes_received	10/10	1.12MiB ≤ 1.25MiB	bounds checks dashboard
✅	quality_gate_logs	intake_connections	10/10	17 ≤ 40	bounds checks dashboard
✅	quality_gate_logs	memory_usage	10/10	185.14MiB ≤ 195MiB	bounds checks dashboard
✅	quality_gate_logs	missed_bytes	10/10	0B = 0B	bounds checks dashboard
✅	quality_gate_logs	total_bytes_received	10/10	264.14MiB ≤ 292MiB	bounds checks dashboard
✅	quality_gate_metrics_logs	cpu_usage	10/10	367.03 ≤ 2000	bounds checks dashboard
✅	quality_gate_metrics_logs	intake_connections	10/10	19 ≤ 40	bounds checks dashboard
✅	quality_gate_metrics_logs	memory_usage	10/10	381.77MiB ≤ 430MiB	bounds checks dashboard
✅	quality_gate_metrics_logs	missed_bytes	10/10	0B = 0B	bounds checks dashboard
✅	quality_gate_metrics_logs	total_bytes_received	10/10	0.94GiB ≤ 1.04GiB	bounds checks dashboard
✅	quality_gate_private_action_runner	memory_usage	10/10	71.83MiB ≤ 75MiB	bounds checks dashboard
✅	quality_gate_security_idle	cpu_usage	10/10	28.41 ≤ 100	bounds checks dashboard
✅	quality_gate_security_idle	memory_usage	10/10	300.85MiB ≤ 330MiB	bounds checks dashboard
✅	quality_gate_security_mean_fs_load	cpu_usage	10/10	57.81 ≤ 200	bounds checks dashboard
✅	quality_gate_security_mean_fs_load	memory_usage	10/10	280.41MiB ≤ 310MiB	bounds checks dashboard
✅	quality_gate_security_no_fs_load	cpu_usage	10/10	26.04 ≤ 100	bounds checks dashboard
✅	quality_gate_security_no_fs_load	memory_usage	10/10	286.73MiB ≤ 320MiB	bounds checks dashboard

Explanation

Confidence level: 90.00%
Effect size tolerance: |Δ mean %| ≥ 5.00%

Performance changes are noted in the perf column of each table:

• ✅ = significantly better comparison variant performance
• ❌ = significantly worse comparison variant performance
• ➖ = no significant change in performance

A regression test is an A/B test of target performance in a repeatable rig, where "performance" is measured as "comparison variant minus baseline variant" for an optimization goal (e.g., ingress throughput). Due to intrinsic variability in measuring that goal, we can only estimate its mean value for each experiment; we report uncertainty in that value as a 90.00% confidence interval denoted "Δ mean % CI".

For each experiment, we decide whether a change in performance is a "regression" -- a change worth investigating further -- if all of the following criteria are true:

1. Its estimated |Δ mean %| ≥ 5.00%, indicating the change is big enough to merit a closer look.

2. Its 90.00% confidence interval "Δ mean % CI" does not contain zero, indicating that if our statistical model is accurate, there is at least a 90.00% chance there is a difference in performance between baseline and comparison variants.

3. Its configuration does not mark it "erratic".

Replicate Execution Details

We run multiple replicates for each experiment/variant. However, we allow replicates to be automatically retried if there are any failures, up to 8 times, at which point the replicate is marked dead and we are unable to run analysis for the entire experiment. We call each of these attempts at running replicates a replicate execution. This section lists all replicate executions that failed due to the target crashing or being oom killed.

Note: In the below tables we bucket failures by experiment, variant, and failure type. For each of these buckets we list out the replicate indexes that failed with an annotation signifying how many times said replicate failed with the given failure mode. In the below example the baseline variant of the experiment named experiment_with_failures had two replicates that failed by oom kills. Replicate 0, which failed 8 executions, and replicate 1 which failed 6 executions, all with the same failure mode.

Experiment	Variant	Replicates	Failure	Logs	Debug Dashboard
experiment_with_failures	baseline	0 (x8) 1 (x6)	Oom killed		Debug Dashboard

The debug dashboard links will take you to a debugging dashboard specifically designed to investigate replicate execution failures.

❌ Retried Profiling Replicate Execution Failures (ddprof)

Note: Profiling replicas may still be executing. See the debug dashboard for up to date status.

Experiment	Variant	Replicates	Failure	Debug Dashboard
quality_gate_idle	comparison	10	Oom killed	Debug Dashboard
quality_gate_idle_all_features	baseline	10	Oom killed	Debug Dashboard
quality_gate_idle_all_features	comparison	10	Oom killed	Debug Dashboard
quality_gate_logs	comparison	10	Oom killed	Debug Dashboard
quality_gate_metrics_logs	baseline	10	Oom killed	Debug Dashboard
quality_gate_metrics_logs	comparison	10	Oom killed	Debug Dashboard
quality_gate_security_idle	baseline	10	Crashed (exit code: 134)	Debug Dashboard
quality_gate_security_idle	comparison	10	Oom killed	Debug Dashboard
quality_gate_security_mean_fs_load	baseline	10	Crashed (exit code: 134)	Debug Dashboard
quality_gate_security_no_fs_load	comparison	10	Oom killed	Debug Dashboard

CI Pass/Fail Decision

✅ Passed. All Quality Gates passed.

• quality_gate_logs, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check missed_bytes: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check total_bytes_received: 10/10 replicas passed. Gate passed.
• quality_gate_security_idle, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_security_idle, bounds check cpu_usage: 10/10 replicas passed. Gate passed.
• quality_gate_security_mean_fs_load, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_security_mean_fs_load, bounds check cpu_usage: 10/10 replicas passed. Gate passed.
• quality_gate_idle_all_features, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_idle_all_features, bounds check total_bytes_received: 10/10 replicas passed. Gate passed.
• quality_gate_idle_all_features, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check missed_bytes: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check cpu_usage: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check total_bytes_received: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_private_action_runner, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_idle, bounds check total_bytes_received: 10/10 replicas passed. Gate passed.
• quality_gate_idle, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_idle, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_security_no_fs_load, bounds check cpu_usage: 10/10 replicas passed. Gate passed.
• quality_gate_security_no_fs_load, bounds check memory_usage: 10/10 replicas passed. Gate passed.