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page aligned allocators, if you are not using huge pages please disable, it'll provide slight performance improvement

v1
Brett 2024-03-06 20:35:54 -05:00
parent a71adc328e
commit bb695ab703
1 changed files with 149 additions and 39 deletions
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180
include/blt/std/allocator.h
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@ -29,7 +29,9 @@
#include <cstdlib>
#ifdef __unix__
#include <sys/mman.h>
#endif
namespace blt
@ -537,18 +539,77 @@ namespace blt
}
};
template<blt::size_t BLOCK_SIZE = 4096 * 16>
template<blt::size_t BLOCK_SIZE = 4096 * 512, bool USE_HUGE = true, blt::size_t HUGE_PAGE_SIZE = 4096 * 512>
class bump_allocator2
{
// power of two
static_assert(BLOCK_SIZE && ((BLOCK_SIZE & (BLOCK_SIZE - 1)) == 0));
static_assert(((BLOCK_SIZE & (BLOCK_SIZE - 1)) == 0) && "Must be a power of two!");
private:
template<typename LOG_FUNC>
static void handle_mmap_error(LOG_FUNC func = BLT_ERROR_STREAM)
{
#define BLT_WRITE(arg) func << arg << '\n';
switch (errno)
{
case EACCES:
BLT_WRITE("fd not set to open!");
break;
case EAGAIN:
BLT_WRITE("The file has been locked, or too much memory has been locked");
break;
case EBADF:
BLT_WRITE("fd is not a valid file descriptor");
break;
case EEXIST:
BLT_WRITE("MAP_FIXED_NOREPLACE was specified in flags, and the range covered "
"by addr and length clashes with an existing mapping.");
break;
case EINVAL:
BLT_WRITE("We don't like addr, length, or offset (e.g., they are too large, or not aligned on a page boundary).");
BLT_WRITE("Or length was 0");
BLT_WRITE("Or flags contained none of MAP_PRIVATE, MAP_SHARED, or MAP_SHARED_VALIDATE.");
break;
case ENFILE:
BLT_WRITE("The system-wide limit on the total number of open files has been reached.");
break;
case ENODEV:
BLT_WRITE("The underlying filesystem of the specified file does not support memory mapping.");
break;
case ENOMEM:
BLT_WRITE("No memory is available.");
BLT_WRITE("Or The process's maximum number of mappings would have been exceeded. "
"This error can also occur for munmap(), when unmapping a region in the middle of an existing mapping, "
"since this results in two smaller mappings on either side of the region being unmapped.");
BLT_WRITE("Or The process's RLIMIT_DATA limit, described in getrlimit(2), would have been exceeded.");
BLT_WRITE("Or We don't like addr, because it exceeds the virtual address space of the CPU.");
break;
case EOVERFLOW:
BLT_WRITE("On 32-bit architecture together with the large file extension (i.e., using 64-bit off_t): "
"the number of pages used for length plus number of "
"pages used for offset would overflow unsigned long (32 bits).");
break;
case EPERM:
BLT_WRITE("The prot argument asks for PROT_EXEC but the mapped area "
"belongs to a file on a filesystem that was mounted no-exec.");
BLT_WRITE("Or The operation was prevented by a file seal");
BLT_WRITE("Or The MAP_HUGETLB flag was specified, but the caller "
"was not privileged (did not have the CAP_IPC_LOCK capability) "
"and is not a member of the sysctl_hugetlb_shm_group group; "
"see the description of /proc/sys/vm/sysctl_hugetlb_shm_group");
break;
case ETXTBSY:
BLT_WRITE("MAP_DENYWRITE was set but the object specified by fd is open for writing.");
break;
}
}
struct block
{
struct
{
blt::size_t allocated_objects = 0;
block* next = nullptr;
block* prev = nullptr;
blt::u8* offset = nullptr;
} metadata;
blt::u8 buffer[BLOCK_SIZE - sizeof(metadata)]{};
@ -562,16 +623,46 @@ namespace blt
block* base = nullptr;
block* head = nullptr;
std::vector<block*> allocated_blocks;
block* allocate_block()
{
auto* buffer = reinterpret_cast<block*>(std::aligned_alloc(BLOCK_SIZE, BLOCK_SIZE));
block* buffer;
#ifdef __unix__
if constexpr (USE_HUGE)
{
static_assert((BLOCK_SIZE & (HUGE_PAGE_SIZE - 1)) == 0 && "Must be multiple of the huge page size!");
buffer = static_cast<block*>(mmap(nullptr, BLOCK_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0));
// if we fail to allocate a huge page we can try to allocate normally
if (buffer == MAP_FAILED)
{
BLT_WARN_STREAM << "We failed to allocate huge pages\n";
handle_mmap_error(BLT_WARN_STREAM);
buffer = static_cast<block*>(mmap(nullptr, BLOCK_SIZE * 2, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0));
if (buffer == MAP_FAILED)
{
BLT_ERROR_STREAM << "Failed to allocate normal pages\n";
handle_mmap_error(BLT_ERROR_STREAM);
throw std::bad_alloc();
}
blt::size_t bytes = BLOCK_SIZE * 2;
auto* ptr = static_cast<void*>(buffer);
buffer = static_cast<block*>(std::align(BLOCK_SIZE, BLOCK_SIZE, ptr, bytes));
}
} else
buffer = reinterpret_cast<block*>(std::aligned_alloc(BLOCK_SIZE, BLOCK_SIZE));
#else
buffer = reinterpret_cast<block*>(std::aligned_alloc(BLOCK_SIZE, BLOCK_SIZE));
#endif
construct(buffer);
allocated_blocks.push_back(buffer);
return buffer;
}
void allocate_forward()
{
auto* block = allocate_block();
block->metadata.prev = head;
head->metadata.next = block;
head = block;
}
@ -579,19 +670,28 @@ namespace blt
template<typename T>
T* allocate_back()
{
size_t remaining_bytes = BLOCK_SIZE - static_cast<size_t>(head->metadata.offset - head->buffer);
blt::size_t remaining_bytes = BLOCK_SIZE - static_cast<blt::size_t>(head->metadata.offset - head->buffer);
auto pointer = static_cast<void*>(head->metadata.offset);
const auto aligned_address = std::align(alignof(T), sizeof(T), pointer, remaining_bytes);
if (aligned_address != nullptr)
{
head->metadata.allocated_objects++;
head->metadata.offset = static_cast<blt::u8*>(aligned_address) + sizeof(T);
}
return static_cast<T*>(aligned_address);
}
// auto& back = blocks.back();
// size_t remaining_bytes = size_ - static_cast<size_t>(back.offset - back.buffer);
// auto pointer = static_cast<void*>(back.offset);
// const auto aligned_address = std::align(alignof(T), sizeof(T), pointer, remaining_bytes);
// if (aligned_address != nullptr)
// {
// back.offset = static_cast<blt::u8*>(aligned_address) + sizeof(T);
// back.allocated_objects++;
// }
//
// return static_cast<T*>(aligned_address);
inline void del(block* p)
{
if constexpr (USE_HUGE)
{
if (munmap(p, BLOCK_SIZE))
{
BLT_ERROR_STREAM << "FAILED TO DEALLOCATE BLOCK\n";
handle_mmap_error(BLT_ERROR_STREAM);
}
}else
free(p);
}
public:
@ -600,16 +700,45 @@ namespace blt
base = head = allocate_block();
};
explicit bump_allocator2(blt::size_t): bump_allocator2()
{}
template<typename T>
[[nodiscard]] T* allocate()
{
if constexpr (sizeof(T) > BLOCK_SIZE)
throw std::bad_alloc();
if (T* ptr = allocate_back<T>(); ptr == nullptr)
allocate_forward();
else
return ptr;
if (T* ptr = allocate_back<T>(); ptr == nullptr)
throw std::bad_alloc();
else
return ptr;
}
template<typename T>
void deallocate(T* p)
{
if (p == nullptr)
return;
//BLT_DEBUG(p);
auto* blk = reinterpret_cast<block*>(reinterpret_cast<std::uintptr_t>(p) & static_cast<std::uintptr_t>(~(BLOCK_SIZE - 1)));
//BLT_TRACE(blk);
//for (const auto& v : allocated_blocks)
// BLT_INFO(" %p", v);
if (--blk->metadata.allocated_objects == 0)
{
if (blk == base)
base = allocate_block();
if (blk->metadata.prev != nullptr)
blk->metadata.prev->metadata.next = blk->metadata.next;
del(blk);
}
}
template<typename T, typename... Args>
@ -638,30 +767,11 @@ namespace blt
while (next != nullptr)
{
auto* after = next->metadata.next;
free(next);
del(next);
next = after;
}
}
};
template<typename T>
class constexpr_allocator
{
public:
constexpr constexpr_allocator() = default;
constexpr T* allocate(blt::size_t n)
{
return ::new T[n];
}
constexpr void deallocate(T* t, blt::size_t)
{
::delete[] t;
}
BLT_CPP20_CONSTEXPR ~constexpr_allocator() = default;
};
}
#define BLT_ALLOCATOR_H