e240dd279a
If the operating system will allocate private pages on demand for the pagemap then use the FlatPageMap by default as it generates better code for deallocation.
52 lines
1.6 KiB
C++
52 lines
1.6 KiB
C++
#pragma once
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namespace snmalloc
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{
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/**
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* Flags in a bitfield of optional features that a PAL may support. These
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* should be set in the PAL's `pal_features` static constexpr field.
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*/
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enum PalFeatures : uint64_t
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{
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/**
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* This PAL supports low memory notifications. It must implement a
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* `low_memory_epoch` method that returns a `uint64_t` of the number of
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* times that a low-memory notification has been raised and an
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* `expensive_low_memory_check()` method that returns a `bool` indicating
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* whether low memory conditions are still in effect.
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*/
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LowMemoryNotification = (1 << 0),
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/**
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* This PAL natively supports allocation with a guaranteed alignment. If
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* this is not supported, then we will over-allocate and round the
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* allocation.
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*
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* A PAL that does supports this must expose a `request()` method that takes
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* a size and alignment. A PAL that does *not* support it must expose a
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* `request()` method that takes only a size.
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*/
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AlignedAllocation = (1 << 1),
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/**
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* This PAL natively supports lazy commit of pages. This means have large
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* allocations and not touching them does not up memory usage. This is
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* exposed in the P
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*/
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LazyCommit = (1 << 2),
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};
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/**
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* Flag indicating whether requested memory should be zeroed.
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*/
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enum ZeroMem
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{
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/**
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* Memory should not be zeroed, contents are undefined.
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*/
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NoZero,
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/**
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* Memory must be zeroed. This can be lazily allocated via a copy-on-write
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* mechanism as long as any load from the memory returns zero.
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*/
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YesZero
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};
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} // namespace snmalloc
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