Benchmark: just another for loop performancewwjshw

Script Preparation code:

var array = new Array(100000).fill(Math.random())

Tests:

cached
let tmp = []; let k = array.length; for (let i = 0; i < k; i++) { tmp.push(array[i]+i) }; console.log(tmp)
uncached
let tmp = []; for (let i = 0; i < array.length; i++) { tmp.push(array[i] + i); }; console.log(tmp)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
cached
uncached

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

I'll break down the provided benchmark definition and test cases to explain what's being tested, compared, and their pros and cons.

**Benchmark Definition JSON**

The provided benchmark definition is for two microbenchmarks:

1. "cached"
2. "uncached"

Each benchmark has a script preparation code that generates an array of 100,000 random numbers using `Math.random()`.

**Test Cases**

There are two test cases:

### Cached

```javascript
let tmp = [];
let k = array.length;
for (let i = 0; i < k; i++) {
    tmp.push(array[i] + i);
}
console.log(tmp);
```

In this benchmark, the `array` variable is accessed multiple times in the loop. This suggests that the test case is trying to measure the performance impact of accessing an array by index versus pushing elements onto an array.

### Uncached

```javascript
let tmp = [];
for (let i = 0; i < array.length; i++) {
    tmp.push(array[i] + i);
}
console.log(tmp);
```

In this benchmark, `array` is accessed only once before the loop. This suggests that the test case is trying to measure the performance impact of accessing an array by index versus pushing elements onto an array when access is repeated.

**Library and Purpose**

The library used in both benchmarks appears to be none, as no external libraries are imported or referenced.

**Special JS Feature or Syntax**

There doesn't appear to be any special JavaScript features or syntax being tested. The code uses standard JavaScript constructs like `for` loops, array indexing, and the `push()` method.

**Pros and Cons of Approaches**

1. **Cached**: This approach accesses `array` by index multiple times in a loop. This may:
	* Reduce cache misses, as the same index is accessed repeatedly.
	* Increase cache locality, making it more efficient for modern CPUs that use cache hierarchies.
	* However, it may:
		+ Increase the number of cache lines being fetched, potentially leading to slower performance due to increased memory access latency.
2. **Uncached**: This approach accesses `array` only once before the loop. This may:
	* Reduce cache hits, as the array is accessed from memory instead of the cache.
	* Decrease cache locality, making it less efficient for CPUs that rely on cache hierarchies.
	* However, it may:
		+ Increase the number of cache lines being fetched in subsequent iterations, potentially leading to slower performance due to increased memory access latency.

**Other Considerations**

When interpreting these results, consider the following:

* The device platform and operating system used for testing (Android) might affect the performance characteristics.
* The specific hardware and CPU architecture of the test environment may influence the results.
* Modern CPUs often use various optimization techniques, such as loop unrolling or cache-aware optimizations, to improve performance. These optimizations might skew the results in one direction.

**Alternatives**

If you want to compare other approaches, consider:

* Using a different data structure, like an array of objects or an array of primitives.
* Adding more complex operations within the loop (e.g., multiplying elements by a constant).
* Using `let` or `const` instead of `var`.
* Implementing memoization or caching for repeated function calls.

Please note that these alternatives will require additional setup and adjustments to the benchmark definition.

Related benchmarks:

just another for loop performancewwjshw (version: 0)

cached vs uncached

Comparing performance of: cached vs uncached

Created: 4 years ago by: Guest

Jump to the latest result

cached

uncached

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):