├── README.md
├── cache-friendly.js
└── cache-unfriendly.js


/README.md:
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 1 | # nodejs-cpu-cache
 2 | 
 3 | Examples showing the impact of cache misses in an interpreted language
 4 | 
 5 | ```console
 6 | $ time node cache-friendly.js
 7 | node cache-friendly.js  0.59s user 0.16s system 101% cpu 0.738 total
 8 | $ time node cache-unfriendly.js
 9 | node cache-unfriendly.js  1.04s user 0.13s system 101% cpu 1.145 total
10 | ```
11 | 
12 | ```sh
13 | perf stat -B -e cache-references,cache-misses,cycles,instructions,branches,fault -- node --interpreted-frames-native-stack --perf-basic-prof cache-unfriendly.js
14 | ```
15 | 


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/cache-friendly.js:
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 1 | const assert = require('assert')
 2 | 
 3 | const width = 1e4;
 4 | const height = 1e4;
 5 | 
 6 | let valueToAvoidDeadCode;
 7 | 
 8 | const image = [];
 9 | 
10 | for(let x = 0; x < width; ++x) {
11 |   image[x] = []
12 |   for(let y = 0; y < height; ++y) {
13 |     image[x][y] = 0
14 |   }
15 | }
16 | 
17 | for(let x = 0; x < width; ++x) {
18 |   for(let y = 0; y < height; ++y) {
19 |     valueToAvoidDeadCode = image[x][y];
20 |   }
21 | }
22 | 
23 | assert.ok(valueToAvoidDeadCode === 0)
24 | 


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/cache-unfriendly.js:
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 1 | const assert = require('assert')
 2 | 
 3 | const width = 1e4;
 4 | const height = 1e4;
 5 | 
 6 | let valueToAvoidDeadCode;
 7 | 
 8 | const image = [];
 9 | 
10 | for(let x = 0; x < width; ++x) {
11 |   image[x] = []
12 |   for(let y = 0; y < height; ++y) {
13 |     image[x][y] = 0
14 |   }
15 | }
16 | 
17 | for(let y = 0; y < height; ++y) {
18 |   for(let x = 0; x < width; ++x) {
19 |     valueToAvoidDeadCode = image[x][y];
20 |   }
21 | }
22 | 
23 | assert.ok(valueToAvoidDeadCode === 0)
24 | 


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