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Kernel: Use find_largest_not_above in VirtualRangeAllocator

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Instead of iterating over the regions in the tree which is O(n), we can
just use RedBlackTree's find_largest_not_above method, which is O(logn)
This commit is contained in:
Idan Horowitz 2021-10-07 22:55:34 +03:00 committed by Andreas Kling
parent 49259777ef
commit 4174fe0156
Notes: sideshowbarker 2024-07-18 02:56:36 +09:00 
Author: https://github.com/IdanHo
Commit: https://github.com/SerenityOS/serenity/commit/4174fe0156e
Pull-request: https://github.com/SerenityOS/serenity/pull/10396
2 changed files with 14 additions and 15 deletions
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27
Kernel/Memory/VirtualRangeAllocator.cpp
View file

@ -42,13 +42,13 @@ void VirtualRangeAllocator::dump() const
}
}
void VirtualRangeAllocator::carve_at_iterator(auto& it, VirtualRange const& range)
void VirtualRangeAllocator::carve_from_region(VirtualRange const& from, VirtualRange const& range)
{
VERIFY(m_lock.is_locked());
auto remaining_parts = (*it).carve(range);
auto remaining_parts = from.carve(range);
VERIFY(remaining_parts.size() >= 1);
VERIFY(m_total_range.contains(remaining_parts[0]));
m_available_ranges.remove(it.key());
m_available_ranges.remove(from.base().get());
m_available_ranges.insert(remaining_parts[0].base().get(), remaining_parts[0]);
if (remaining_parts.size() == 2) {
VERIFY(m_total_range.contains(remaining_parts[1]));
@ -122,7 +122,7 @@ KResultOr<VirtualRange> VirtualRangeAllocator::try_allocate_anywhere(size_t size
m_available_ranges.remove(it.key());
return allocated_range;
}
carve_at_iterator(it, allocated_range);
carve_from_region(*it, allocated_range);
return allocated_range;
}
dmesgln("VirtualRangeAllocator: Failed to allocate anywhere: size={}, alignment={}", size, alignment);
@ -142,18 +142,17 @@ KResultOr<VirtualRange> VirtualRangeAllocator::try_allocate_specific(VirtualAddr
return ENOMEM;
SpinlockLocker lock(m_lock);
for (auto it = m_available_ranges.begin(); !it.is_end(); ++it) {
auto& available_range = *it;
if (!available_range.contains(base, size))
continue;
if (available_range == allocated_range) {
m_available_ranges.remove(it.key());
return allocated_range;
}
carve_at_iterator(it, allocated_range);
auto available_range = m_available_ranges.find_largest_not_above(base.get());
if (!available_range)
return ENOMEM;
if (!available_range->contains(allocated_range))
return ENOMEM;
if (*available_range == allocated_range) {
m_available_ranges.remove(available_range->base().get());
return allocated_range;
}
return ENOMEM;
carve_from_region(*available_range, allocated_range);
return allocated_range;
}
void VirtualRangeAllocator::deallocate(VirtualRange const& range)

2
Kernel/Memory/VirtualRangeAllocator.h
View file

@ -31,7 +31,7 @@ public:
bool contains(VirtualRange const& range) const { return m_total_range.contains(range); }
private:
void carve_at_iterator(auto&, VirtualRange const&);
void carve_from_region(VirtualRange const& from, VirtualRange const&);
RedBlackTree<FlatPtr, VirtualRange> m_available_ranges;
VirtualRange m_total_range;