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AK: Give BumpAllocator a single-block cache

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This avoid excessive mmap/munmap traffic in normal operation.
This commit is contained in:
Ali Mohammad Pur 2021-09-12 18:11:35 +04:30 committed by Ali Mohammad Pur
parent e4b1c0b8b1
commit a72eea6408
Notes: sideshowbarker 2024-07-18 08:59:31 +09:00 
Author: https://github.com/alimpfard
Commit: https://github.com/SerenityOS/serenity/commit/a72eea64085
Pull-request: https://github.com/SerenityOS/serenity/pull/9976
1 changed files with 26 additions and 12 deletions
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38
AK/BumpAllocator.h
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@ -62,6 +62,13 @@ public:
if (!m_head_chunk)
return;
for_each_chunk([this](auto chunk) {
if (!s_unused_allocation_cache) {
auto next_chunk = ((ChunkHeader const*)chunk)->next_chunk;
if (!next_chunk) {
s_unused_allocation_cache = chunk;
return;
}
}
if constexpr (use_mmap) {
munmap((void*)chunk, m_chunk_size);
} else {
@ -91,18 +98,22 @@ protected:
// dbgln("Allocated {} entries in previous chunk and have {} unusable bytes", m_allocations_in_previous_chunk, m_chunk_size - m_byte_offset_into_current_chunk);
// m_allocations_in_previous_chunk = 0;
void* new_chunk;
if constexpr (use_mmap) {
#ifdef __serenity__
new_chunk = serenity_mmap(nullptr, m_chunk_size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_RANDOMIZED | MAP_PRIVATE, 0, 0, m_chunk_size, "BumpAllocator Chunk");
#else
new_chunk = mmap(nullptr, m_chunk_size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
#endif
if (new_chunk == MAP_FAILED)
return false;
if (s_unused_allocation_cache) {
new_chunk = (void*)exchange(s_unused_allocation_cache, 0);
} else {
new_chunk = kmalloc(m_chunk_size);
if (!new_chunk)
return false;
if constexpr (use_mmap) {
#ifdef __serenity__
new_chunk = serenity_mmap(nullptr, m_chunk_size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_RANDOMIZED | MAP_PRIVATE, 0, 0, m_chunk_size, "BumpAllocator Chunk");
#else
new_chunk = mmap(nullptr, m_chunk_size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
#endif
if (new_chunk == MAP_FAILED)
return false;
} else {
new_chunk = kmalloc(m_chunk_size);
if (!new_chunk)
return false;
}
}
auto& new_header = *(ChunkHeader*)new_chunk;
@ -134,7 +145,7 @@ protected:
FlatPtr m_current_chunk { 0 };
size_t m_byte_offset_into_current_chunk { 0 };
size_t m_chunk_size { 0 };
// size_t m_allocations_in_previous_chunk { 0 };
static FlatPtr s_unused_allocation_cache;
};
template<typename T, bool use_mmap = false, size_t chunk_size = use_mmap ? 4 * MiB : 4 * KiB>
@ -172,6 +183,9 @@ public:
}
};
template<bool use_mmap, size_t size>
inline FlatPtr BumpAllocator<use_mmap, size>::s_unused_allocation_cache { 0 };
}
using AK::BumpAllocator;