Block Reuse Quiz

Trace the representation, diagnose a boundary failure, and reconstruct a changed case.

Get every question correct to pass this checkpoint. You can review feedback, revise your answers, and submit again.

1. The reuse allocator has blocks [40 free, 24 used, 72 free]. Two requests of 32 arrive. Which capacities are selected? Select one.

Select one answer.

40 then 40 72 then 40 40 then 72 24 then 40

2. A 96-byte free block serves a 20-byte request without splitting. Which stored capacity should remain? Select one.

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96 20 in every allocator by definition 76 0 because the block is now live

3. Two threads both see the same free block before either marks it used. Why is an atomic list head alone insufficient? Select one.

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Atomic pointers prevent all callbacks from running The payload bytes must be zero before reuse The search-and-claim transition on block metadata still races First fit is safe only with exactly one block

4. A free block has capacity 48. A request for 49 arrives. Can that block satisfy it without growth or merging? Answer yes or no.

5. A free 72-byte block is the first fit. Two calls to find_free_block(32) occur with no intervening allocation. What should happen? Select one.

Select one answer.

The first call claims it and the second returns NULL The block is split after the first search Both return its header without changing flags or capacity The list head moves to its successor

6. Blocks are [16 free,64 used,16 free]. Can a request of 24 be served without growth, splitting, or moving live data? Answer yes or no.

7. No free block fits and the growth helper fails. Which state is correct? Select one.

Select one answer.

Head, links, flags, capacities, and live bytes are unchanged The last visited free block becomes used The last successor points to (void*)-1 All blocks become free to make space

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