SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/tech-cache-line-64-bytes

On a cache miss, how much data does a typical modern CPU cache pull in from memory?

A 64-byte block, not just the few bytes asked for.

Start playing free

  1. Exactly the bytes requested
  2. A 64-byte block ✔
  3. A whole 4 MB page

Why: Caches move data in blocks called cache lines, commonly 64 bytes. A 64-byte line can hold sixteen 4-byte integers, so sequential reads often reuse data already fetched into cache.

Huh, didn't know that: A cache miss fetches a whole cache block, not only the bytes requested by the current instruction.

The dad joke
Why did the cache bring 64 bytes when asked for 4? It's a dad. It always packs snacks for later.
Like this card?
Play the game

References

Answer: A 64-byte block. Caches move data in blocks called cache lines, commonly 64 bytes. A 64-byte line can hold sixteen 4-byte integers, so sequential reads often reuse data already fetched into cache.

  1. OpenStax Introduction to Computer Science 5.5: Memory Hierarchy openstax.org/books/introduction-computer-science/pages/5-5-memory-hierarchy
    In most processors available now, the cache usually brings 64 bytes from the memory.
    Checked 2026-10-10.

Think this answer is wrong? Tap "Challenge this answer" on the card in the game and tell us why.

Test yourself in the game

Tech & GadgetsCPU cache is built from SRAM. Why isn't all of a computer's memory SRAM?Tech & GadgetsA loop reuses the same few variables thousands of times. Which kind of locality is that?Tech & GadgetsWhy does DRAM, the main memory in a computer, need to be refreshed every few milliseconds?

That's stuff everyone should know.