https://www.youngju.dev/blog 천천히 올바르게. AI Researcher & DevOps Engineer Youngju's blog. GPU/CUDA, LLM, MLOps, Kubernetes AI workloads, and data engineering — plus mindset essays on confidence, routines, health, and sport psychology. ko fjvbn2003@gmail.com (Youngju Kim) fjvbn2003@gmail.com (Youngju Kim) Sun, 09 Aug 2026 00:00:00 GMT https://www.youngju.dev/blog/linux/2026-08-09-syscall-path-is-the-performance-budget.en https://www.youngju.dev/blog/linux/2026-08-09-syscall-path-is-the-performance-budget.en Through the case of turning a CMF Phone 1 into a personal infrastructure server, this post lays out where the real cost of a Linux compatibility layer actually lands. After failing to flash postmarketOS, the author kept stock Android and used Termux as the host control plane; ordinary web services ran fine under PRoot, but the Chromium-based workload alone could not reach the CPU that was sitting idle, because of the userspace translation layer. The fix was not code but a change of execution path — rooting the phone and entering a real chroot so that native syscalls are used. Along with the general principle that follows, we also cover why a compatibility layer must never be mistaken for an isolation boundary. Sun, 09 Aug 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) linuxtermuxchrootprootself-hostingnamespaceandroid https://www.youngju.dev/blog/linux/2026-08-09-syscall-path-is-the-performance-budget.ja https://www.youngju.dev/blog/linux/2026-08-09-syscall-path-is-the-performance-budget.ja CMF Phone 1を個人インフラのサーバーにした事例を通じて、Linux互換レイヤの実際のコストがどこに付くのかを整理します。著者はpostmarketOSのフラッシュに失敗したあとストックのAndroidを維持し、Termuxをホストの制御プレーンとしました。一般的なウェブサービスはPRootで十分でしたが、Chromiumベースのワークロードだけはユーザースペースの変換レイヤのせいで余っているCPUに到達できませんでした。解決はコードではなく実行経路を変えること、つまりroot化して本物のchrootへ入りネイティブなシステムコールを使うことでした。ここから出てくる一般原則とともに、互換レイヤを隔離境界と取り違えてはいけない理由も扱います。 Sun, 09 Aug 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) linuxtermuxchrootprootself-hostingnamespaceandroid https://www.youngju.dev/blog/linux/2026-08-09-syscall-path-is-the-performance-budget https://www.youngju.dev/blog/linux/2026-08-09-syscall-path-is-the-performance-budget CMF Phone 1을 개인 인프라 서버로 만든 사례를 통해 리눅스 호환 계층의 실제 비용이 어디에 붙는지 정리합니다. 저자는 postmarketOS 플래싱에 실패한 뒤 스톡 안드로이드를 유지하고 Termux를 호스트 제어 평면으로 삼았으며, 일반 웹 서비스는 PRoot로 충분했지만 Chromium 기반 워크로드만은 유저스페이스 변환 계층 때문에 남는 CPU에 도달하지 못했습니다. 해결은 코드가 아니라 실행 경로를 바꾸는 것, 즉 루팅 후 실제 chroot로 진입해 네이티브 시스템 콜을 쓰는 것이었습니다. 여기서 나오는 일반 원칙과 함께, 호환 계층을 격리 경계로 착각하면 안 되는 이유도 다룹니다. Sun, 09 Aug 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) linuxtermuxchrootprootself-hostingnamespaceandroid https://www.youngju.dev/blog/linux/2026-08-09-syscall-path-is-the-performance-budget.zh https://www.youngju.dev/blog/linux/2026-08-09-syscall-path-is-the-performance-budget.zh 本文借一个把 CMF Phone 1 变成个人基础设施服务器的案例，梳理 Linux 兼容层的真实代价究竟落在哪里。作者刷 postmarketOS 失败之后保留了原厂 Android，把 Termux 当作宿主控制平面；一般的 Web 服务用 PRoot 就够了，唯独基于 Chromium 的负载因为用户态转换层而够不着那些闲着的 CPU。解法不是改代码，而是改执行路径 —— root 之后进入真正的 chroot，用上原生系统调用。文中在给出由此得到的一般原则的同时，也讨论了为什么绝不能把兼容层误当成隔离边界。 Sun, 09 Aug 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) linuxtermuxchrootprootself-hostingnamespaceandroid