std.heap.PageAllocator updates to fix race condition and utilize NtAllocateVirtualMemory / NtFreeVirtualMemory instead of VirtualAlloc / VirtualFree #23097
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…ondition and utilize NtAllocateVirtualMemory / NtFreeVirtualMemory instead of VirtualAlloc and VirtualFree
…+ add missing alloction constants MEM_RESERVE_PLACEHOLDER / MEM_PRESERVE_PLACEHOLDER
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Looks good to me and it agrees with what I've learnt about those |
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Good work, thank you. A possible improvement could be to only try the first code path when the requested alignment is below page_size_min, otherwise jump straight to the second strategy. |
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This PR attempts to address some of the concerns outlined in #22846
Two new functions (
NtAllocateVirtualMemoryandNtFreeVirtualMemory) were added tontdll.zigandwindows.zigas an FFI signature and Zig wrapper, respectively.Changes made to
std.heap.PageAllocatorinclude:Usage of
VirtualAllocandVirtualFreehas been replaced with their respective NT counterpart and memory allocations are now using placeholder constants to prevent the race condition previously present. Lastly, instead of freeing the entire region - the unaligned portions at the head and tail of the region are freed which should improve performance.