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dqn: Only poison commit pages to speed up poison of large arenas

This commit is contained in:
doyle 2023-08-29 23:04:14 +10:00
parent b624ef1da5
commit 76cc1f278c
1 changed files with 12 additions and 2 deletions
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14
dqn_memory.cpp
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@ -232,11 +232,15 @@ DQN_API Dqn_MemBlock *Dqn_MemBlock_Init(Dqn_usize reserve, Dqn_usize commit, uin
result->commit = commit_aligned - metadata_size;
result->flags = DQN_CAST(uint8_t)flags;
if (DQN_ASAN_POISON) { // NOTE: Poison (guard page + entire block), we unpoison as we allocate
// NOTE: Poison (guard page + commit). We do *not* poison the entire
// block, only the commit pages. Since we may reserve large amounts of
// space vs commit we'd waste time marking those pages as poisoned as
// reads or writes outside of committed pages will page fault.
if (DQN_ASAN_POISON) {
DQN_ASSERT(Dqn_IsPowerOfTwoAligned(result->data, DQN_ASAN_POISON_ALIGNMENT));
DQN_ASSERT(Dqn_IsPowerOfTwoAligned(result->size, DQN_ASAN_POISON_ALIGNMENT));
void *poison_ptr = DQN_CAST(void *)Dqn_AlignUpPowerOfTwo(DQN_CAST(char *)result + sizeof(Dqn_MemBlock), DQN_ASAN_POISON_ALIGNMENT);
Dqn_usize bytes_to_poison = DQN_ASAN_POISON_GUARD_SIZE + result->size;
Dqn_usize bytes_to_poison = DQN_ASAN_POISON_GUARD_SIZE + result->commit;
Dqn_ASAN_PoisonMemoryRegion(poison_ptr, bytes_to_poison);
}
}
@ -274,6 +278,12 @@ DQN_API void *Dqn_MemBlock_Alloc(Dqn_MemBlock *block, Dqn_usize size, uint8_t al
block->commit += commit_size;
Dqn_VMem_Commit(commit_ptr, commit_size, Dqn_VMemPage_ReadWrite);
DQN_ASSERT(block->commit <= block->size);
if (DQN_ASAN_POISON) { // NOTE: Poison newly committed pages that aren't being used.
void *poison_ptr = DQN_CAST(char *)block->data + block->used;
Dqn_usize bytes_to_poison = block->commit - block->used;
Dqn_ASAN_PoisonMemoryRegion(poison_ptr, bytes_to_poison);
}
}
return result;