[infra] Reduce default build parallelism

[vikuznetsov-nvidia]

Leave CPU, power, and SMT headroom while retaining the Docker build's memory cap.

Summary by CodeRabbit

• Bug Fixes
  • Improved default build parallelism to use approximately half of the available CPU cores.
  • Added memory-aware limits to help prevent excessive resource usage during Docker builds.
  • Updated build output and option documentation to accurately reflect the new defaults.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 57f42cc and e1a4049.

📒 Files selected for processing (2)

• build_release.sh
• scripts/build_cuvslam_in_docker.sh

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📝 Walkthrough

Walkthrough

Build scripts now default to approximately half the detected CPU count for parallel jobs. The Docker build also retains its available-memory cap and selects the lower CPU or memory limit. Usage text reflects the updated calculations.

Changes

Build parallelism defaults

Layer / File(s)	Summary
CPU- and memory-bounded job defaults build_release.sh, scripts/build_cuvslam_in_docker.sh	Release builds calculate MAKE_JOBS as ceil(nproc/2), while Docker builds select the lower of the halved CPU count and memory-based cap. Usage messages describe the updated defaults.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested reviewers: hrabeti-nvidia, slepichev

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: lowering the default build parallelism.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch vikuznetsov/reduce-build-parallelism

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[github-actions]

Test Results

Status	Platform	Language	Total	Passed	Failed	Errors	Skipped
✅	Orin	C++	16	16	0	0	0
✅	Orin	Python	71	70	0	0	1
✅	Thor	C++	16	16	0	0	0
✅	Thor	Python	71	70	0	0	1
✅	x86_64	C++	16	16	0	0	0
✅	x86_64	Python	71	70	0	0	1

cuVSLAM Evaluation KPIs

Config	Dataset	ATE,%	ARE,º/m	Kabsch,	Losts,	diff ATE,%	diff ARE,º/m	diff Kabsch,	diff Losts,	FPS,Hz
x86_64-cuda12.6.3-ubuntu24.04	KITTI-STEREO_ODOM	0.8415	0.0023	2.8399	0	NA	NA	NA	NA	308.3
x86_64-cuda12.6.3-ubuntu24.04	KITTI-STEREO_SLAM	0.7496	0.0019	1.8795	0	NA	NA	NA	NA	185.3

Artifacts

• eval-html-report
• eval-kpis-pr
• test-results-x86_64
• docs-html
• test-results-orin
• test-results-thor