Went with a linked list of free blocks and handled merging adjacent blocks on deallocation.
Start by clarifying requirements (e.g., allocation sizes, performance goals, concurrency) and then outline a design using a free list with boundary tags to enable coalescing. Explain the data structures, algorithms for allocation/deallocation, and how coalescing reduces fragmentation, while discussing trade-offs like time vs. space overhead.
Pro tip: Mention real-world allocators like dlmalloc or jemalloc to show practical awareness, and emphasize how your design handles edge cases such as coalescing with adjacent free blocks and avoiding fragmentation.
Ask about expected allocation patterns, size ranges, performance metrics (throughput, latency), and whether the allocator needs to be thread-safe. This ensures your design targets the right priorities.
Decide on a free list organization (e.g., segregated free lists by size class) and metadata per block (size, free/used flag, boundary tags). Explain how these enable efficient coalescing.
Describe how to find a suitable free block (first-fit, best-fit, etc.), split it if necessary, and update metadata. For deallocation, mark block as free and attempt coalescing with adjacent free blocks using boundary tags.
Explain how coalescing reduces external fragmentation by merging adjacent free blocks. Discuss internal fragmentation and strategies to mitigate it (e.g., size classes, splitting).
Cover trade-offs: time overhead of coalescing vs. memory savings, metadata overhead, and potential concurrency strategies (e.g., per-thread caches, locks). Mention possible optimizations like deferred coalescing.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.