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https://github.com/RGBCube/serenity
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Kernel: Remove old SlabAllocator :^)
This is no longer useful since kmalloc() does automatic slab allocation without any of the limitations of the old SlabAllocator. :^)
This commit is contained in:
Andreas Kling
parent
66d35f2936
commit
3399b6c57f
9 changed files with 0 additions and 245 deletions
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/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/Assertions.h>
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#include <AK/Memory.h>
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#include <Kernel/Heap/SlabAllocator.h>
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#include <Kernel/Heap/kmalloc.h>
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#include <Kernel/Memory/Region.h>
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#include <Kernel/Sections.h>
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#define SANITIZE_SLABS
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namespace Kernel {
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template<size_t templated_slab_size>
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class SlabAllocator {
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public:
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SlabAllocator() = default;
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void init(size_t size)
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{
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m_base = kmalloc_eternal(size);
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m_end = (u8*)m_base + size;
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FreeSlab* slabs = (FreeSlab*)m_base;
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m_slab_count = size / templated_slab_size;
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for (size_t i = 1; i < m_slab_count; ++i) {
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slabs[i].next = &slabs[i - 1];
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}
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slabs[0].next = nullptr;
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m_freelist = &slabs[m_slab_count - 1];
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m_num_allocated = 0;
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}
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constexpr size_t slab_size() const { return templated_slab_size; }
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size_t slab_count() const { return m_slab_count; }
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void* alloc()
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{
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FreeSlab* free_slab;
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{
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// We want to avoid being swapped out in the middle of this
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ScopedCritical critical;
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FreeSlab* next_free;
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free_slab = m_freelist.load(AK::memory_order_consume);
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do {
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if (!free_slab)
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return kmalloc(slab_size());
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// It's possible another processor is doing the same thing at
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// the same time, so next_free *can* be a bogus pointer. However,
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// in that case compare_exchange_strong would fail and we would
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// try again.
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next_free = free_slab->next;
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} while (!m_freelist.compare_exchange_strong(free_slab, next_free, AK::memory_order_acq_rel));
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m_num_allocated++;
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}
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#ifdef SANITIZE_SLABS
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memset(free_slab, SLAB_ALLOC_SCRUB_BYTE, slab_size());
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#endif
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return free_slab;
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}
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void dealloc(void* ptr)
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{
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VERIFY(ptr);
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if (ptr < m_base || ptr >= m_end) {
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kfree_sized(ptr, slab_size());
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return;
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}
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FreeSlab* free_slab = (FreeSlab*)ptr;
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#ifdef SANITIZE_SLABS
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if (slab_size() > sizeof(FreeSlab*))
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memset(free_slab->padding, SLAB_DEALLOC_SCRUB_BYTE, sizeof(FreeSlab::padding));
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#endif
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// We want to avoid being swapped out in the middle of this
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ScopedCritical critical;
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FreeSlab* next_free = m_freelist.load(AK::memory_order_consume);
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do {
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free_slab->next = next_free;
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} while (!m_freelist.compare_exchange_strong(next_free, free_slab, AK::memory_order_acq_rel));
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m_num_allocated--;
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}
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size_t num_allocated() const { return m_num_allocated; }
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size_t num_free() const { return m_slab_count - m_num_allocated; }
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private:
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struct FreeSlab {
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FreeSlab* next;
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char padding[templated_slab_size - sizeof(FreeSlab*)];
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};
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Atomic<FreeSlab*> m_freelist { nullptr };
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Atomic<size_t, AK::MemoryOrder::memory_order_relaxed> m_num_allocated { 0 };
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size_t m_slab_count { 0 };
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void* m_base { nullptr };
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void* m_end { nullptr };
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static_assert(AssertSize<FreeSlab, templated_slab_size>());
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};
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static SlabAllocator<16> s_slab_allocator_16;
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static SlabAllocator<32> s_slab_allocator_32;
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static SlabAllocator<64> s_slab_allocator_64;
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static SlabAllocator<128> s_slab_allocator_128;
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static SlabAllocator<256> s_slab_allocator_256;
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#if ARCH(I386)
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static_assert(sizeof(Memory::Region) <= s_slab_allocator_128.slab_size());
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#endif
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template<typename Callback>
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ErrorOr<void> for_each_allocator(Callback callback)
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{
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TRY(callback(s_slab_allocator_16));
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TRY(callback(s_slab_allocator_32));
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TRY(callback(s_slab_allocator_64));
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TRY(callback(s_slab_allocator_128));
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TRY(callback(s_slab_allocator_256));
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return {};
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}
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UNMAP_AFTER_INIT void slab_alloc_init()
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{
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s_slab_allocator_16.init(128 * KiB);
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s_slab_allocator_32.init(128 * KiB);
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s_slab_allocator_64.init(512 * KiB);
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s_slab_allocator_128.init(512 * KiB);
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s_slab_allocator_256.init(128 * KiB);
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}
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void* slab_alloc(size_t slab_size)
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{
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if (slab_size <= 16)
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return s_slab_allocator_16.alloc();
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if (slab_size <= 32)
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return s_slab_allocator_32.alloc();
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if (slab_size <= 64)
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return s_slab_allocator_64.alloc();
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if (slab_size <= 128)
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return s_slab_allocator_128.alloc();
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if (slab_size <= 256)
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return s_slab_allocator_256.alloc();
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VERIFY_NOT_REACHED();
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}
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void slab_dealloc(void* ptr, size_t slab_size)
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{
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if (slab_size <= 16)
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return s_slab_allocator_16.dealloc(ptr);
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if (slab_size <= 32)
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return s_slab_allocator_32.dealloc(ptr);
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if (slab_size <= 64)
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return s_slab_allocator_64.dealloc(ptr);
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if (slab_size <= 128)
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return s_slab_allocator_128.dealloc(ptr);
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if (slab_size <= 256)
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return s_slab_allocator_256.dealloc(ptr);
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VERIFY_NOT_REACHED();
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}
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ErrorOr<void> slab_alloc_stats(Function<ErrorOr<void>(size_t slab_size, size_t allocated, size_t free)> callback)
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{
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TRY(for_each_allocator([&](auto& allocator) -> ErrorOr<void> {
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auto num_allocated = allocator.num_allocated();
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auto num_free = allocator.slab_count() - num_allocated;
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TRY(callback(allocator.slab_size(), num_allocated, num_free));
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return {};
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}));
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return {};
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}
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}
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@ -1,44 +0,0 @@
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/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Error.h>
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#include <AK/Function.h>
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#include <AK/Types.h>
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namespace Kernel {
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#define SLAB_ALLOC_SCRUB_BYTE 0xab
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#define SLAB_DEALLOC_SCRUB_BYTE 0xbc
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void* slab_alloc(size_t slab_size);
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void slab_dealloc(void*, size_t slab_size);
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void slab_alloc_init();
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ErrorOr<void> slab_alloc_stats(Function<ErrorOr<void>(size_t slab_size, size_t allocated, size_t free)>);
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#define MAKE_SLAB_ALLOCATED(type) \
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public: \
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[[nodiscard]] void* operator new(size_t) \
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{ \
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void* ptr = slab_alloc(sizeof(type)); \
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VERIFY(ptr); \
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return ptr; \
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} \
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[[nodiscard]] void* operator new(size_t, const std::nothrow_t&) noexcept \
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{ \
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return slab_alloc(sizeof(type)); \
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} \
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void operator delete(void* ptr) noexcept \
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{ \
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if (!ptr) \
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return; \
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slab_dealloc(ptr, sizeof(type)); \
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} \
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\
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private:
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}
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