Align heap to 64 bytes #119
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mohanson
approved these changes
Oct 16, 2024
XuJiandong
requested changes
Oct 16, 2024
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| static mut _BUDDY_HEAP: _AlignedHeap<$heap_size> = _AlignedHeap([0u8; $heap_size]); | ||
| static mut _FIXED_BLOCK_HEAP: _AlignedHeap<$fixed_block_heap_size> = | ||
| _AlignedHeap([0u8; $fixed_block_heap_size]); | ||
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| #[global_allocator] | ||
| static ALLOC: $crate::buddy_alloc::NonThreadsafeAlloc = unsafe { | ||
| let fast_param = $crate::buddy_alloc::FastAllocParam::new( |
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It's suggested to insert a checking function here to make sure all ptr are aligned with 64.
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If HEAP is aligned to 64 bytes, buddy-alloc allocated ptrs are aligned to 64.
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Previously, the reported error was misleading and made debugging very difficult. If the error occurs due to incorrect configuration, troubleshooting would be much more straightforward.
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- We already have a debug assertion https://github.com/jjyr/buddy-alloc/blob/master/src/fast_alloc.rs#L116
- But unfortunately, we can't trigger a panic or assert from the global allocator, because the panic itself depends on the allocator, I believe the reported error is triggerred by this assertion.
#[repr(align(64))]is guaranteed by the compiler, it is not exposed tockb-stdusers, so they have no chance t mis-configure this.
XuJiandong
approved these changes
Oct 16, 2024
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jjyr/buddy-alloc#18 (comment)
buddy-alloc 0.5 uses
ptr#write_alignedwhich costs more cycles thanwrite.In 0.6 we assume the heap memory is aligned to 64 bytes, so we can switch to
ptr::write.