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Kernel: Support best fit allocation policy in kmalloc()

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Add find_best_fit() which implements best fit allocation algorithm.
Kmalloc now uses a best fit allocation policy for large allocations.
This commit is contained in:
nimelehin 2020-03-10 14:36:20 +03:00 • committed by Andreas Kling
parent 0d08ed2693
commit c0a4cf5e8d
2 changed files with 39 additions and 1 deletions
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11
Kernel/Heap/kmalloc.cpp
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@ -150,7 +150,16 @@ void* kmalloc_impl(size_t size)
size_t chunks_needed = (real_size + CHUNK_SIZE - 1) / CHUNK_SIZE;
Bitmap bitmap_wrapper = Bitmap::wrap(alloc_map, POOL_SIZE / CHUNK_SIZE);
auto first_chunk = bitmap_wrapper.find_first_fit(chunks_needed);
Optional<size_t> first_chunk;
// Choose the right politic for allocation.
constexpr u32 best_fit_threshold = 128;
if (chunks_needed < best_fit_threshold) {
first_chunk = bitmap_wrapper.find_first_fit(chunks_needed);
} else {
first_chunk = bitmap_wrapper.find_best_fit(chunks_needed);
}
if (!first_chunk.has_value()) {
klog() << "kmalloc(): PANIC! Out of memory (no suitable block for size " << size << ")";
Kernel::dump_backtrace();