https://bugs.webkit.org/show_bug.cgi?id=138495
Reviewed by Mark Lam.
iOS has a per-process virtual memory cap around 1GB, so there's some
value to not going totally ham with virtual memory.
We currently use about 8X the necessary amount:
- 2X to align our VM allocation
- 4X to reserve small / medium / (2) large chunk VM ranges per superchunk
We can cut that down:
- Return the unaligned portion of our VM allocation (-2X)
- Use all the chunks in a superchunk, instead of allocating one
chunk per superchunk (-4X)
* bmalloc/Algorithm.h:
(bmalloc::roundUpToMultipleOf): Added a non-constant version of this
function so we can call it with getpagesize() at runtime.
* bmalloc/Chunk.h:
* bmalloc/LargeChunk.h:
(bmalloc::LargeChunk::create): Deleted. Instead of each chunk allocating
its own VM, VMHeap allocates the superchunk and all the chunks in it at a time.
* bmalloc/VMAllocate.h:
(bmalloc::vmValidate):
(bmalloc::vmAllocate): ASSERT that mmap succeeds to make crashes clearer
if it does not succeed. Allocate precisely, and give back the extra.
* bmalloc/VMHeap.cpp:
(bmalloc::VMHeap::allocateSuperChunk):
(bmalloc::VMHeap::allocateSmallChunk): Deleted.
(bmalloc::VMHeap::allocateMediumChunk): Deleted.
(bmalloc::VMHeap::allocateLargeChunk): Deleted. Use all the chunks
in a superchunk, instead of just one.
* bmalloc/VMHeap.h:
(bmalloc::VMHeap::allocateSmallPage):
(bmalloc::VMHeap::allocateMediumPage):
(bmalloc::VMHeap::allocateLargeRange):
* bmalloc/XLargeChunk.h:
(bmalloc::XLargeChunk::create): Updated to match changes above.
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@175751
268f45cc-cd09-0410-ab3c-
d52691b4dbfc
+2014-11-07 Geoffrey Garen <ggaren@apple.com>
+
+ bmalloc uses 8X more virtual memory than necessary
+ https://bugs.webkit.org/show_bug.cgi?id=138495
+
+ Reviewed by Mark Lam.
+
+ iOS has a per-process virtual memory cap around 1GB, so there's some
+ value to not going totally ham with virtual memory.
+
+ We currently use about 8X the necessary amount:
+ - 2X to align our VM allocation
+ - 4X to reserve small / medium / (2) large chunk VM ranges per superchunk
+
+ We can cut that down:
+ - Return the unaligned portion of our VM allocation (-2X)
+ - Use all the chunks in a superchunk, instead of allocating one
+ chunk per superchunk (-4X)
+
+ * bmalloc/Algorithm.h:
+ (bmalloc::roundUpToMultipleOf): Added a non-constant version of this
+ function so we can call it with getpagesize() at runtime.
+
+ * bmalloc/Chunk.h:
+ * bmalloc/LargeChunk.h:
+ (bmalloc::LargeChunk::create): Deleted. Instead of each chunk allocating
+ its own VM, VMHeap allocates the superchunk and all the chunks in it at a time.
+
+ * bmalloc/VMAllocate.h:
+ (bmalloc::vmValidate):
+ (bmalloc::vmAllocate): ASSERT that mmap succeeds to make crashes clearer
+ if it does not succeed. Allocate precisely, and give back the extra.
+
+ * bmalloc/VMHeap.cpp:
+ (bmalloc::VMHeap::allocateSuperChunk):
+ (bmalloc::VMHeap::allocateSmallChunk): Deleted.
+ (bmalloc::VMHeap::allocateMediumChunk): Deleted.
+ (bmalloc::VMHeap::allocateLargeChunk): Deleted. Use all the chunks
+ in a superchunk, instead of just one.
+
+ * bmalloc/VMHeap.h:
+ (bmalloc::VMHeap::allocateSmallPage):
+ (bmalloc::VMHeap::allocateMediumPage):
+ (bmalloc::VMHeap::allocateLargeRange):
+ * bmalloc/XLargeChunk.h:
+ (bmalloc::XLargeChunk::create): Updated to match changes above.
+
2014-11-01 David Kilzer <ddkilzer@apple.com>
JavaScriptCore is missing debug info for bmalloc because libbmalloc.a is stripped
return !!(reinterpret_cast<uintptr_t>(value) & mask);
}
+template<typename T> inline T roundUpToMultipleOf(size_t divisor, T x)
+{
+ BASSERT(divisor && !(divisor & (divisor - 1)));
+ return reinterpret_cast<T>((reinterpret_cast<uintptr_t>(x) + (divisor - 1ul)) & ~(divisor - 1ul));
+}
+
template<size_t divisor, typename T> inline constexpr T roundUpToMultipleOf(T x)
{
static_assert(divisor && !(divisor & (divisor - 1)), "'divisor' must be a power of two.");
- return reinterpret_cast<T>((reinterpret_cast<uintptr_t>(x) + (divisor - 1ul)) & ~(divisor - 1ul));
+ return roundUpToMultipleOf(divisor, x);
}
template<size_t divisor, typename T> inline constexpr T roundDownToMultipleOf(T x)
static const size_t chunkOffset = Traits::chunkOffset;
static const uintptr_t chunkMask = Traits::chunkMask;
- static Chunk* create();
static Chunk* get(void*);
Page* begin() { return Page::get(Line::get(m_memory)); }
alignas(vmPageSize) char m_memory[];
};
-template<class Traits>
-inline auto Chunk<Traits>::create() -> Chunk*
-{
- size_t vmSize = bmalloc::vmSize(chunkSize);
- std::pair<void*, Range> result = vmAllocate(vmSize, superChunkSize, chunkOffset);
- return new (result.first) Chunk;
-}
-
template<class Traits>
inline auto Chunk<Traits>::get(void* object) -> Chunk*
{
alignas(vmPageSize) char m_memory[];
};
-inline LargeChunk* LargeChunk::create()
-{
- size_t vmSize = bmalloc::vmSize(largeChunkSize);
- std::pair<void*, Range> result = vmAllocate(vmSize, superChunkSize, largeChunkOffset);
- return new (result.first) LargeChunk;
-}
-
inline LargeChunk* LargeChunk::get(void* object)
{
BASSERT(!isSmallOrMedium(object));
{
return roundUpToMultipleOf<vmPageSize>(size);
}
-
+
inline void vmValidate(size_t vmSize)
{
+ // We use getpagesize() here instead of vmPageSize because vmPageSize is
+ // allowed to be larger than the OS's true page size.
+
UNUSED(vmSize);
BASSERT(vmSize);
- BASSERT(vmSize == bmalloc::vmSize(vmSize));
+ BASSERT(vmSize == roundUpToMultipleOf(static_cast<size_t>(getpagesize()), vmSize));
}
inline void vmValidate(void* p, size_t vmSize)
{
- vmValidate(vmSize);
-
// We use getpagesize() here instead of vmPageSize because vmPageSize is
// allowed to be larger than the OS's true page size.
+
+ vmValidate(vmSize);
+
UNUSED(p);
BASSERT(p);
BASSERT(p == mask(p, ~(getpagesize() - 1)));
inline void* vmAllocate(size_t vmSize)
{
vmValidate(vmSize);
- return mmap(0, vmSize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, BMALLOC_VM_TAG, 0);
+ void* result = mmap(0, vmSize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, BMALLOC_VM_TAG, 0);
+ RELEASE_BASSERT(result != MAP_FAILED);
+ return result;
}
inline void vmDeallocate(void* p, size_t vmSize)
munmap(p, vmSize);
}
-// Allocates vmSize bytes at a specified offset from a power-of-two alignment.
-// Use this function to create pointer masks that aren't simple powers of two.
+// Allocates vmSize bytes at a specified power-of-two alignment.
+// Use this function to create maskable memory regions.
-inline std::pair<void*, Range> vmAllocate(size_t vmSize, size_t alignment, size_t offset)
+inline void* vmAllocate(size_t vmSize, size_t vmAlignment)
{
vmValidate(vmSize);
- BASSERT(isPowerOfTwo(alignment));
+ vmValidate(vmAlignment);
- size_t mappedSize = std::max(vmSize, alignment) + alignment;
+ size_t mappedSize = std::max(vmSize, vmAlignment) + vmAlignment;
char* mapped = static_cast<char*>(vmAllocate(mappedSize));
+ char* mappedEnd = mapped + mappedSize;
+
+ char* aligned = roundUpToMultipleOf(vmAlignment, mapped);
+ char* alignedEnd = aligned + vmSize;
+
+ if (size_t leftExtra = aligned - mapped)
+ vmDeallocate(mapped, leftExtra);
- uintptr_t alignmentMask = alignment - 1;
- if (!test(mapped, alignmentMask) && offset + vmSize <= alignment) {
- // We got two perfectly aligned regions. Give one back to avoid wasting
- // VM unnecessarily. This isn't costly because we aren't making holes.
- vmDeallocate(mapped + alignment, alignment);
- return std::make_pair(mapped + offset, Range(mapped, alignment));
- }
-
- // We got an unaligned region. Keep the whole thing to avoid creating holes,
- // and hopefully realign the VM allocator for future allocations. On Darwin,
- // VM holes trigger O(N^2) behavior in mmap, so we want to minimize them.
- char* mappedAligned = mask(mapped, ~alignmentMask) + alignment;
- return std::make_pair(mappedAligned + offset, Range(mapped, mappedSize));
+ if (size_t rightExtra = mappedEnd - alignedEnd)
+ vmDeallocate(alignedEnd, rightExtra);
+
+ return aligned;
}
inline void vmDeallocatePhysicalPages(void* p, size_t vmSize)
{
}
-void VMHeap::allocateSmallChunk()
+void VMHeap::allocateSuperChunk()
{
- SmallChunk* chunk = SmallChunk::create();
- for (auto* it = chunk->begin(); it != chunk->end(); ++it)
+ char* superChunk = static_cast<char*>(vmAllocate(superChunkSize, superChunkSize));
+
+ SmallChunk* smallChunk = new (superChunk + smallChunkOffset) SmallChunk;
+ for (auto* it = smallChunk->begin(); it != smallChunk->end(); ++it)
m_smallPages.push(it);
-}
-void VMHeap::allocateMediumChunk()
-{
- MediumChunk* chunk = MediumChunk::create();
- for (auto* it = chunk->begin(); it != chunk->end(); ++it)
+ MediumChunk* mediumChunk = new (superChunk + mediumChunkOffset) MediumChunk;
+ for (auto* it = mediumChunk->begin(); it != mediumChunk->end(); ++it)
m_mediumPages.push(it);
-}
-Range VMHeap::allocateLargeChunk()
-{
- LargeChunk* chunk = LargeChunk::create();
- return BoundaryTag::init(chunk);
+ LargeChunk* largeChunk = new (superChunk + largeChunkOffset) LargeChunk;
+ m_largeRanges.insert(BoundaryTag::init(largeChunk));
}
} // namespace bmalloc
void deallocateLargeRange(std::unique_lock<StaticMutex>&, Range);
private:
- void allocateSmallChunk();
- void allocateMediumChunk();
- Range allocateLargeChunk();
+ void allocateSuperChunk();
Vector<SmallPage*> m_smallPages;
Vector<MediumPage*> m_mediumPages;
inline SmallPage* VMHeap::allocateSmallPage()
{
if (!m_smallPages.size())
- allocateSmallChunk();
+ allocateSuperChunk();
return m_smallPages.pop();
}
inline MediumPage* VMHeap::allocateMediumPage()
{
if (!m_mediumPages.size())
- allocateMediumChunk();
+ allocateSuperChunk();
return m_mediumPages.pop();
}
inline Range VMHeap::allocateLargeRange(size_t size)
{
Range range = m_largeRanges.take(size);
- if (!range)
- range = allocateLargeChunk();
+ if (!range) {
+ allocateSuperChunk();
+ range = m_largeRanges.take(size);
+ BASSERT(range);
+ }
return range;
}
inline XLargeChunk* XLargeChunk::create(size_t size)
{
size_t vmSize = bmalloc::vmSize(sizeof(XLargeChunk) + size);
- std::pair<void*, Range> result = vmAllocate(vmSize, superChunkSize, largeChunkOffset);
- return new (result.first) XLargeChunk(result.second, size);
+ auto xlargeChunk = vmAllocate(vmSize, superChunkSize);
+ return new (xlargeChunk) XLargeChunk(Range(xlargeChunk, vmSize), size);
}
inline void XLargeChunk::destroy(XLargeChunk* chunk)
git://git.webkit.org / WebKit-https.git / commitdiff