February 2026 — sched-ext/scx: Delivered a unified VTime update path in the stopping function by removing the split_vtime_updates flag, resulting in a simpler, more stable and faster vtime update flow during shutdown sequences. This refactor reduces complexity, mitigates edge-case risks in stopping(), and aligns with a unified time-update strategy. The change is supported by commit 5f647e7f2052bb030461a324c3c7ceab4b886871, which documents the removal of the flag initially introduced in #2978 to enable unified updates while preserving backward compatibility during the transition.

2026-01 Performance-focused monthly summary for sched-ext/scx. The month focused on locality-oriented scheduling improvements, stronger CPU affinity controls, and clearer queue-domain management in multi-LLC environments. Key features and changes delivered include: 1) LLC-aware Scheduler Enhancements: introduced per-LLC vtime tracking, weighted LLC selection, and the ability to populate CPU-to-LLC topology mappings from userspace; exposed via an --enable-llc-awareness toggle. 2) Cross-LLC work stealing: enabled stealing of tasks from sibling LLC queues when local work is exhausted, with per-task and per-cell steal stats; requires --enable-llc-awareness and is controlled by --enable-work-stealing. 3) Enforce Complete Cell Pinning Policy: added --reject-multicpu-pinning to reject multi-CPU affinities that do not cover the entire cell (cell 0 exempt; single-CPU pinning remains allowed). 4) Typed DSQ Encoding for Scx Mitotis Queues: introduced a typed dispatch queue encoding to distinguish per-CPU and cell+LLC domain queues, with helper functions to construct, validate, and parse DSQ IDs for clearer queue management. 5) Codebase refactor for BPF headers: reorganized mitosis-related BPF headers to support LLC-aware scheduling (scx_mitosis: header restructuring). Overall, these changes lay the groundwork for higher performance and more predictable scheduling in multi-LLC systems, leveraging topology awareness, improved locality, and clearer queue semantics.

November 2025: Stabilized the core scheduling path in sched-ext/scx through a focused mitosis scheduling stability fix. Corrected DSQ vtime updates to apply to the CPU's cell context during stopping, addressing edge cases where tasks are pinned to CPUs outside their cell. This reduces runnable task stalls, prevents unintended mitosis eviction, and improves overall scheduler reliability and throughput. Tech levers: low-level scheduling logic, CPU/cell context handling, and regression-focused debugging.

Month: 2025-10 — Stabilized vtime synchronization in sched-ext/scx by unifying vtime updates (cell, CPU, and task) within stopping(), preventing large vtime drifts and related errors. Introduced a backward-compatible toggle (--split-vtime-updates) to restore legacy behavior when needed. This work reduces scheduling anomalies in mitosis paths and improves overall timing accuracy for long-running tasks with wide nice value ranges.

2025-06 Monthly Summary for sched-ext/scx. Delivered enhanced observability for Scheduler Queue Placement in scx_mitosis with global and per-cell queue metrics, enabling faster debugging and performance tuning. Implemented logging for queue placement decisions, with distributions across queue types and tracking affinity violations. Updated BPF code, headers, and the main Rust application to collect, compute, and display metrics. Committed changes to log global + per-cell queue counts (commit 5db364f954b86c83f08c50cdbccf86a4cea1018a). Business value: improved visibility reduces mean time to identify scheduling bottlenecks, accelerates optimization and reliability. Technologies demonstrated: Rust, BPF, kernel/user-space instrumentation, observability tooling, data aggregation and reporting. Major bugs fixed: none this month.

April 2025 (Month: 2025-04) - Key feature delivered: Introduced a new 'get' action for the 'ruleset' object in the bfcli front-end API to retrieve the current ruleset and associated counters from the daemon. This enables CLI-driven visibility into policy state and runtime metrics, supporting faster issue diagnosis and policy auditing. Major bugs fixed: No major bugs reported for this period in the bpfilter repository. Overall impact and accomplishments: Enhances operational visibility and control over runtime rulesets, reducing mean time to insight and improving reliability of policy enforcement. Demonstrates end-to-end API surface work, alignment with existing design patterns, and concrete progress toward observability goals. Technologies/skills demonstrated: Front-end API extension, client-server contract design, daemon/frontend integration, isolated changelist with a traceable commit, and code contributions in a living open-source project.