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Addressing CR feedback

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This commit is contained in:
Matthew Parkinson
2019-01-16 17:03:15 +00:00
parent c4e6af4bad
commit ab57c86e3a
2 changed files with 22 additions and 10 deletions
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13
src/mem/alloc.h
View File

@@ -38,10 +38,17 @@ namespace snmalloc
PMMediumslab = 2
};
#ifndef SNMALLOC_MAX_FLATPAGEMAP_SIZE
// Use flat map is under a single node.
# define SNMALLOC_MAX_FLATPAGEMAP_SIZE PAGEMAP_NODE_SIZE
#endif
static constexpr bool USE_FLATPAGEMAP = SNMALLOC_MAX_FLATPAGEMAP_SIZE >=
sizeof(FlatPagemap<SUPERSLAB_BITS, uint8_t>);
using SuperslabPagemap = std::conditional_t<
bits::is64(),
Pagemap<SUPERSLAB_BITS, uint8_t, 0>,
FlatPagemap<SUPERSLAB_BITS, uint8_t>>;
USE_FLATPAGEMAP,
FlatPagemap<SUPERSLAB_BITS, uint8_t>,
Pagemap<SUPERSLAB_BITS, uint8_t, 0>>;
HEADER_GLOBAL SuperslabPagemap global_pagemap;
/**

19
src/mem/pagemap.h
View File

@@ -7,13 +7,13 @@
namespace snmalloc
{
static constexpr size_t PAGEMAP_NODE_BITS = 16;
static constexpr size_t PAGEMAP_NODE_SIZE = 1ULL << PAGEMAP_NODE_BITS;
template<size_t GRANULARITY_BITS, typename T, T default_content>
class Pagemap
{
private:
static constexpr size_t PAGEMAP_BITS = 16;
static constexpr size_t PAGEMAP_SIZE = 1 << PAGEMAP_BITS;
static constexpr size_t COVERED_BITS =
bits::ADDRESS_BITS - GRANULARITY_BITS;
static constexpr size_t POINTER_BITS =
@@ -22,14 +22,15 @@ namespace snmalloc
bits::next_pow2_bits_const(sizeof(T));
static_assert(
PAGEMAP_BITS - CONTENT_BITS < COVERED_BITS,
PAGEMAP_NODE_BITS - CONTENT_BITS < COVERED_BITS,
"Should use the FlatPageMap as it does not require a tree");
static constexpr size_t BITS_FOR_LEAF = PAGEMAP_BITS - CONTENT_BITS;
static constexpr size_t BITS_FOR_LEAF = PAGEMAP_NODE_BITS - CONTENT_BITS;
static constexpr size_t ENTRIES_PER_LEAF = 1 << BITS_FOR_LEAF;
static constexpr size_t LEAF_MASK = ENTRIES_PER_LEAF - 1;
static constexpr size_t BITS_PER_INDEX_LEVEL = PAGEMAP_BITS - POINTER_BITS;
static constexpr size_t BITS_PER_INDEX_LEVEL =
PAGEMAP_NODE_BITS - POINTER_BITS;
static constexpr size_t ENTRIES_PER_INDEX_LEVEL = 1 << BITS_PER_INDEX_LEVEL;
static constexpr size_t ENTRIES_MASK = ENTRIES_PER_INDEX_LEVEL - 1;
@@ -85,7 +86,7 @@ namespace snmalloc
value, (PagemapEntry*)LOCKED_ENTRY, std::memory_order_relaxed))
{
auto& v = default_memory_provider;
value = (PagemapEntry*)v.alloc_chunk(PAGEMAP_SIZE);
value = (PagemapEntry*)v.alloc_chunk(PAGEMAP_NODE_SIZE);
e->store(value, std::memory_order_release);
}
else
@@ -229,6 +230,10 @@ namespace snmalloc
}
};
/**
* Simple pagemap that for each GRANULARITY_BITS of the address range
* stores a T.
**/
template<size_t GRANULARITY_BITS, typename T>
class FlatPagemap
{