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ASIC.FYI

Q284FreeSystemVerilog

Return the top K densest pages

Difficulty
Medium
Topic
Memory Systems
Language
SV
Interview prompt

Question

Return at most K individual 4 KiB pages ordered from highest to lowest density.

Page-density records entering a descending ordering stage with blank top-K result slots
Density is the primary key and lower page base is the deterministic tie-breaker.
Starting point

Question code

function automatic void densest_top_k_page_4kb(
  input bit [31:0] mem[longint unsigned],
  input int unsigned k,
  output longint unsigned pages[$],
  output int unsigned densities[$]
);
Reviewed example

Trace one case

Input
page densities={0x1000:3,0x2000:1,0x3000:3,0x4000:2}; K=3
Expected output
[(0x1000,3),(0x3000,3),(0x4000,2)]

Density sorts descending and the lower page base wins the tie between the two density-three pages.

What to cover

Requirements

  1. Return min(K, number of populated pages) records.
  2. Order by density descending.
  3. Break equal-density ties by lower page base.
  4. Clear output queues before appending.
Continue practicing
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