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for-loop cached variables / access caching + V8 hints
(version: 0)
Comparing performance of:
caching variable (for global) vs single access cache vs zero cache - 3x access vs caching variable (for global) V8 hints
Created:
3 years ago
by:
Guest
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Script Preparation code:
var arr = [31,12321,213,21321,321321,321321,1]; var processFunc = a => a + 1;
Tests:
caching variable (for global)
for (let i = arr.length, tmp; i--;) { processFunc(tmp = arr[i]); processFunc(tmp); processFunc(tmp); };
single access cache
for (let i = arr.length; i--;) { let tmp = arr[i]; processFunc(tmp); processFunc(tmp); processFunc(tmp); };
zero cache - 3x access
for (let i = arr.length; i--;) { processFunc(arr[i]); processFunc(arr[i]); processFunc(arr[i]); };
caching variable (for global) V8 hints
for (let i = arr.length, tmp = 0; i--;) { processFunc(tmp = arr[i]); processFunc(tmp); processFunc(tmp); };
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (4)
Previous results
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Test case name
Result
caching variable (for global)
single access cache
zero cache - 3x access
caching variable (for global) V8 hints
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
The provided JSON represents a JavaScript microbenchmarking test case, specifically designed to compare the performance of different caching strategies in a for-loop-based scenario. **Benchmark Overview** The benchmark tests four variations of caching: 1. **Caching variable (for global)**: This approach caches the loop variable `i` in the scope of the function call, allowing the interpreter to reuse it across multiple iterations. 2. **Single access cache**: In this variation, a new local variable `tmp` is created on each iteration, storing the value of `arr[i]`. This allows for caching only the accessed element, not the loop variable itself. 3. **Zero cache - 3x access**: This approach does not cache anything, meaning that on each iteration, the function call will access `arr[i]`, perform the operation, and then return to execute again immediately. 4. **Caching variable (for global) V8 hints**: Similar to the first variation, but with added "V8 hints" which indicate the caching behavior to the JavaScript engine. **Pros and Cons of Each Approach** 1. **Caching variable (for global)**: * Pros: Reuses loop variable across iterations, potentially reducing function call overhead. * Cons: May lead to slower performance due to unnecessary caching. 2. **Single access cache**: * Pros: Only caches the accessed element, minimizing unnecessary memory usage. * Cons: Creates a new local variable on each iteration, increasing function call overhead. 3. **Zero cache - 3x access**: * Pros: Avoids caching, reducing potential performance gains from reusing variables. * Cons: Accesses `arr[i]` on every iteration, leading to significant function call overhead and slow performance. 4. **Caching variable (for global) V8 hints**: * Pros: Combines the benefits of caching with explicit "V8 hints" for better performance guidance. * Cons: May not provide noticeable performance improvements if used incorrectly. **Library Considerations** The provided benchmark definition does not explicitly mention any libraries. However, some variations rely on implicit library behaviors: 1. **Caching variable (for global)** and **Caching variable (for global) V8 hints**: These approaches assume the JavaScript engine will use caching for the loop variable `i`. The added "V8 hints" in the latter variation explicitly inform the engine about this caching behavior. 2. **Single access cache**: This approach relies on JavaScript's implicit local variable creation and assignment mechanics. **Special JS Features or Syntax** The benchmark definition does not include any special JavaScript features or syntax, as it focuses solely on the caching strategies themselves. **Alternative Approaches** Other caching strategies that are not tested in this benchmark include: 1. **Registering variables with `V8.register`**: This API allows developers to explicitly register variables for caching, potentially improving performance. 2. **Using compiler-specific optimizations**: Some JavaScript engines provide compiler-specific optimizations or flags that can improve caching behavior. Keep in mind that these alternative approaches might require additional setup, library integration, or engine-specific configuration, which may not be relevant to this specific benchmarking test case.
Related benchmarks:
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for-loop cached variables / access caching
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