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#include <AK/Assertions.h>
#include <Kernel/Heap/SlabAllocator.h>
#include <Kernel/Heap/kmalloc.h>
#include <Kernel/VM/Region.h>
template<size_t templated_slab_size>
class SlabAllocator {
public:
SlabAllocator() {}
void init(size_t size)
{
void* base = kmalloc_eternal(size);
FreeSlab* slabs = (FreeSlab*)base;
size_t slab_count = size / templated_slab_size;
for (size_t i = 1; i < slab_count; ++i) {
slabs[i].next = &slabs[i - 1];
}
slabs[0].next = nullptr;
m_freelist = &slabs[slab_count - 1];
m_num_allocated = 0;
m_num_free = slab_count;
}
constexpr size_t slab_size() const { return templated_slab_size; }
void* alloc()
{
InterruptDisabler disabler;
ASSERT(m_freelist);
void* ptr = m_freelist;
m_freelist = m_freelist->next;
++m_num_allocated;
--m_num_free;
return ptr;
}
void dealloc(void* ptr)
{
InterruptDisabler disabler;
ASSERT(ptr);
((FreeSlab*)ptr)->next = m_freelist;
m_freelist = (FreeSlab*)ptr;
++m_num_allocated;
--m_num_free;
}
size_t num_allocated() const { return m_num_allocated; }
size_t num_free() const { return m_num_free; }
private:
struct FreeSlab {
FreeSlab* next { nullptr };
char padding[templated_slab_size - sizeof(FreeSlab*)];
};
FreeSlab* m_freelist { nullptr };
size_t m_num_allocated { 0 };
size_t m_num_free { 0 };
static_assert(sizeof(FreeSlab) == templated_slab_size);
};
static SlabAllocator<8> s_slab_allocator_8;
static SlabAllocator<16> s_slab_allocator_16;
static SlabAllocator<32> s_slab_allocator_32;
static SlabAllocator<48> s_slab_allocator_48;
static_assert(sizeof(Region) <= s_slab_allocator_48.slab_size());
template<typename Callback>
void for_each_allocator(Callback callback)
{
callback(s_slab_allocator_8);
callback(s_slab_allocator_16);
callback(s_slab_allocator_32);
callback(s_slab_allocator_48);
}
void slab_alloc_init()
{
s_slab_allocator_8.init(384 * KB);
s_slab_allocator_16.init(128 * KB);
s_slab_allocator_32.init(128 * KB);
s_slab_allocator_48.init(128 * KB);
}
void* slab_alloc(size_t slab_size)
{
if (slab_size <= 8)
return s_slab_allocator_8.alloc();
if (slab_size <= 16)
return s_slab_allocator_16.alloc();
if (slab_size <= 32)
return s_slab_allocator_32.alloc();
if (slab_size <= 48)
return s_slab_allocator_48.alloc();
ASSERT_NOT_REACHED();
}
void slab_dealloc(void* ptr, size_t slab_size)
{
if (slab_size <= 8)
return s_slab_allocator_8.dealloc(ptr);
if (slab_size <= 16)
return s_slab_allocator_16.dealloc(ptr);
if (slab_size <= 32)
return s_slab_allocator_32.dealloc(ptr);
if (slab_size <= 48)
return s_slab_allocator_48.dealloc(ptr);
ASSERT_NOT_REACHED();
}
void slab_alloc_stats(Function<void(size_t slab_size, size_t allocated, size_t free)> callback)
{
for_each_allocator([&](auto& allocator) {
callback(allocator.slab_size(), allocator.num_allocated(), allocator.num_free());
});
}
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