e240dd279a
If the operating system will allocate private pages on demand for the pagemap then use the FlatPageMap by default as it generates better code for deallocation.
88 lines
1.9 KiB
C++
88 lines
1.9 KiB
C++
#pragma once
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#if defined(__linux__)
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# include "../ds/bits.h"
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# include "../mem/allocconfig.h"
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# include <string.h>
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# include <sys/mman.h>
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extern "C" int puts(const char* str);
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namespace snmalloc
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{
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class PALLinux
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{
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public:
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/**
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* Bitmap of PalFeatures flags indicating the optional features that this
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* PAL supports.
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*/
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static constexpr uint64_t pal_features = LazyCommit;
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static void error(const char* const str)
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{
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puts(str);
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abort();
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}
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/// Notify platform that we will not be using these pages
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void notify_not_using(void* p, size_t size) noexcept
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{
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assert(bits::is_aligned_block<OS_PAGE_SIZE>(p, size));
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// Do nothing. Don't call madvise here, as the system call slows the
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// allocator down too much.
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UNUSED(p);
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UNUSED(size);
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}
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/// Notify platform that we will be using these pages
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template<ZeroMem zero_mem>
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void notify_using(void* p, size_t size) noexcept
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{
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assert(
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bits::is_aligned_block<OS_PAGE_SIZE>(p, size) || (zero_mem == NoZero));
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if constexpr (zero_mem == YesZero)
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zero<true>(p, size);
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else
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{
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UNUSED(p);
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UNUSED(size);
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}
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}
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/// OS specific function for zeroing memory
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template<bool page_aligned = false>
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void zero(void* p, size_t size) noexcept
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{
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if (page_aligned || bits::is_aligned_block<OS_PAGE_SIZE>(p, size))
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{
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assert(bits::is_aligned_block<OS_PAGE_SIZE>(p, size));
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madvise(p, size, MADV_DONTNEED);
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}
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else
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{
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::memset(p, 0, size);
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}
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}
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template<bool committed>
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void* reserve(const size_t* size) noexcept
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{
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void* p = mmap(
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nullptr,
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*size,
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PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_ANONYMOUS,
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-1,
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0);
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if (p == MAP_FAILED)
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error("Out of memory");
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return p;
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}
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};
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} // namespace snmalloc
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#endif
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