Add Skip List implementation and unit test for improved scheduler determinism #1287
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test_skip_list.exe
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Why is this binary file included?
test_empty_file.txt
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This appears to be a standalone implementation that is not utilized by the kernel. If you intend to use it in an application, you should be able to do so without issue. However, given that it is not integrated into the kernel's functionality, I don't believe it should be merged into the kernel codebase. |
skip_list.c
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| static int xRandomLevel(void) { | ||
| int level = 1; | ||
| while ((rand() & 0x1) && level < SKIP_LIST_MAX_LEVEL) |
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Wouldn't a better way would be to level = rand()%SKIP_LIST_MAX_LEVEL? Am I missing something?
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Wouldn't a better way would be to
level = rand()%SKIP_LIST_MAX_LEVEL? Am I missing something?
The idea here isn't just to "pick a random number" — it's to generate levels following a geometric distribution, where each higher level is about half as likely as the previous one. This gives us a nice layered effect in the skip list: tons of nodes at level 1, fewer at level 2, even fewer at level 3, and so on.
level = rand() % SKIP_LIST_MAX_LEVEL;
…we’d be assigning levels with uniform probability. That would mean you might end up with too many high-level nodes, which breaks the performance benefits. Worst case, it starts behaving more like a flat list than a skip list.
test_skip_list.c
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I appreciate adding a test for your implementation but consider adding any unit tests here. This would take another PR.
…on to uxListRemove
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Add Skip List implementation and unit test for improved scheduler determinism
Description
This PR introduces a Skip List data structure to the FreeRTOS kernel, providing O(log n) insertion and search for sorted lists. It includes:
This enhancement is intended to improve temporal determinism for scheduler operations that previously relied on O(n) list traversal.
Test Steps
Checklist:
Related Issue
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