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Merged
kunalspathak merged 8 commits into from
Dec 21, 2023
+100 −64
Merged

Reduce use of madvise DODUMP/DONTDUMP #95643

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cd5b665
CV test of Reduce use of madvise DODUMP/DONTDUMP
a74nh Dec 4, 2023
9ecb709
Simplify VirtualReset()
a74nh Dec 6, 2023
ab47f4e
Fix detection of new memory in VIRTUALCommitMemory
a74nh Dec 6, 2023
2338d64
Fix up nits
a74nh Dec 7, 2023
a17fddc
More nits
a74nh Dec 7, 2023
544bea6
Use POSIX_MADV_DONTNEED
a74nh Dec 8, 2023
52d6b8d
Avoid posix_madvise if madvise fails
a74nh Dec 8, 2023
6ca0e0d
Better setting of newMemory
a74nh Dec 20, 2023
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134 changes: 76 additions & 58 deletions src/coreclr/gc/unix/gcenv.unix.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -515,12 +515,13 @@ void GCToOSInterface::YieldThread(uint32_t switchCount)

// Reserve virtual memory range.
// Parameters:
// size - size of the virtual memory range
// alignment - requested memory alignment, 0 means no specific alignment requested
// flags - flags to control special settings like write watching
// size - size of the virtual memory range
// alignment - requested memory alignment, 0 means no specific alignment requested
// flags - flags to control special settings like write watching
// committing - memory will be comitted
// Return:
// Starting virtual address of the reserved range
static void* VirtualReserveInner(size_t size, size_t alignment, uint32_t flags, uint32_t hugePagesFlag = 0)
static void* VirtualReserveInner(size_t size, size_t alignment, uint32_t flags, uint32_t hugePagesFlag, bool committing)
{
assert(!(flags & VirtualReserveFlags::WriteWatch) && "WriteWatch not supported on Unix");
if (alignment < OS_PAGE_SIZE)
Expand Down Expand Up @@ -550,8 +551,11 @@ static void* VirtualReserveInner(size_t size, size_t alignment, uint32_t flags,

pRetVal = pAlignedRetVal;
#ifdef MADV_DONTDUMP
// Do not include reserved memory in coredump.
madvise(pRetVal, size, MADV_DONTDUMP);
// Do not include reserved uncommitted memory in coredump.
if (!committing)
{
madvise(pRetVal, size, MADV_DONTDUMP);
}
#endif
return pRetVal;
}
Expand All @@ -569,7 +573,7 @@ static void* VirtualReserveInner(size_t size, size_t alignment, uint32_t flags,
// Starting virtual address of the reserved range
void* GCToOSInterface::VirtualReserve(size_t size, size_t alignment, uint32_t flags, uint16_t node)
{
return VirtualReserveInner(size, alignment, flags);
return VirtualReserveInner(size, alignment, flags, 0, /* committing */ false);
}

// Release virtual memory range previously reserved using VirtualReserve
Expand All @@ -585,44 +589,21 @@ bool GCToOSInterface::VirtualRelease(void* address, size_t size)
return (ret == 0);
}

// Commit virtual memory range.
// Parameters:
// size - size of the virtual memory range
// Return:
// Starting virtual address of the committed range
void* GCToOSInterface::VirtualReserveAndCommitLargePages(size_t size, uint16_t node)
{
#if HAVE_MAP_HUGETLB
uint32_t largePagesFlag = MAP_HUGETLB;
#elif HAVE_VM_FLAGS_SUPERPAGE_SIZE_ANY
uint32_t largePagesFlag = VM_FLAGS_SUPERPAGE_SIZE_ANY;
#else
uint32_t largePagesFlag = 0;
#endif

void* pRetVal = VirtualReserveInner(size, OS_PAGE_SIZE, 0, largePagesFlag);
if (VirtualCommit(pRetVal, size, node))
{
return pRetVal;
}

return nullptr;
}

// Commit virtual memory range. It must be part of a range reserved using VirtualReserve.
// Parameters:
// address - starting virtual address
// size - size of the virtual memory range
// address - starting virtual address
// size - size of the virtual memory range
// newMemory - memory has been newly allocated
// Return:
// true if it has succeeded, false if it has failed
bool GCToOSInterface::VirtualCommit(void* address, size_t size, uint16_t node)
static bool VirtualCommitInner(void* address, size_t size, uint16_t node, bool newMemory)
{
bool success = mprotect(address, size, PROT_WRITE | PROT_READ) == 0;

#ifdef MADV_DODUMP
if (success)
if (success && !newMemory)
{
// Include committed memory in coredump.
// Include committed memory in coredump. New memory is included by default.
madvise(address, size, MADV_DODUMP);
}
#endif
Expand Down Expand Up @@ -650,6 +631,41 @@ bool GCToOSInterface::VirtualCommit(void* address, size_t size, uint16_t node)
return success;
}

// Commit virtual memory range. It must be part of a range reserved using VirtualReserve.
// Parameters:
// address - starting virtual address
// size - size of the virtual memory range
// Return:
// true if it has succeeded, false if it has failed
bool GCToOSInterface::VirtualCommit(void* address, size_t size, uint16_t node)
{
return VirtualCommitInner(address, size, node, /* newMemory */ false);
}

// Commit virtual memory range.
// Parameters:
// size - size of the virtual memory range
// Return:
// Starting virtual address of the committed range
void* GCToOSInterface::VirtualReserveAndCommitLargePages(size_t size, uint16_t node)
{
#if HAVE_MAP_HUGETLB
uint32_t largePagesFlag = MAP_HUGETLB;
#elif HAVE_VM_FLAGS_SUPERPAGE_SIZE_ANY
uint32_t largePagesFlag = VM_FLAGS_SUPERPAGE_SIZE_ANY;
#else
uint32_t largePagesFlag = 0;
#endif

void* pRetVal = VirtualReserveInner(size, OS_PAGE_SIZE, 0, largePagesFlag, true);
if (VirtualCommitInner(pRetVal, size, node, /* newMemory */ true))
{
return pRetVal;
}

return nullptr;
}

// Decomit virtual memory range.
// Parameters:
// address - starting virtual address
Expand Down Expand Up @@ -686,32 +702,34 @@ bool GCToOSInterface::VirtualDecommit(void* address, size_t size)
// true if it has succeeded, false if it has failed
bool GCToOSInterface::VirtualReset(void * address, size_t size, bool unlock)
{
int st;
#if HAVE_MADV_FREE
// Try to use MADV_FREE if supported. It tells the kernel that the application doesn't
// need the pages in the range. Freeing the pages can be delayed until a memory pressure
// occurs.
st = madvise(address, size, MADV_FREE);
if (st != 0)
#endif
{
#if HAVE_POSIX_MADVISE
// In case the MADV_FREE is not supported, use MADV_DONTNEED
st = posix_madvise(address, size, MADV_DONTNEED);
#else
// If we don't have posix_madvise, report failure
st = EINVAL;
#endif
}
int st = EINVAL;

#if defined(MADV_DONTDUMP) || defined(HAVE_MADV_FREE)

int madviseFlags = 0;

#ifdef MADV_DONTDUMP
if (st == 0)
{
// Do not include reset memory in coredump.
madvise(address, size, MADV_DONTDUMP);
}
// Do not include reset memory in coredump.
madviseFlags |= MADV_DONTDUMP;
#endif

#ifdef HAVE_MADV_FREE
// Tell the kernel that the application doesn't need the pages in the range.
// Freeing the pages can be delayed until a memory pressure occurs.
madviseFlags |= MADV_FREE;
#endif

st = madvise(address, size, madviseFlags);

#endif //defined(MADV_DONTDUMP) || defined(HAVE_MADV_FREE)

#if defined(HAVE_POSIX_MADVISE) && !defined(MADV_DONTDUMP)
// DONTNEED is the nearest posix equivalent of FREE.
// Prefer FREE as, since glibc2.6 DONTNEED is a nop.
st = posix_madvise(address, size, POSIX_MADV_DONTNEED);

#endif //defined(HAVE_POSIX_MADVISE) && !defined(MADV_DONTDUMP)

return (st == 0);
}

Expand Down
30 changes: 24 additions & 6 deletions src/coreclr/pal/src/map/virtual.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -468,14 +468,20 @@ static LPVOID VIRTUALReserveMemory(
IN LPVOID lpAddress, /* Region to reserve or commit */
IN SIZE_T dwSize, /* Size of Region */
IN DWORD flAllocationType, /* Type of allocation */
IN DWORD flProtect) /* Type of access protection */
IN DWORD flProtect, /* Type of access protection */
OUT BOOL *newMemory = NULL) /* Set if new virtual memory is allocated */
{
LPVOID pRetVal = NULL;
UINT_PTR StartBoundary;
SIZE_T MemSize;

TRACE( "Reserving the memory now..\n");

if (newMemory != NULL)
{
*newMemory = false;
}

// First, figure out where we're trying to reserve the memory and
// how much we need. On most systems, requests to mmap must be
// page-aligned and at multiples of the page size. Unlike on Windows, on
Expand Down Expand Up @@ -509,6 +515,11 @@ static LPVOID VIRTUALReserveMemory(
flAllocationType |= MEM_RESERVE_EXECUTABLE;
}
pRetVal = ReserveVirtualMemory(pthrCurrent, (LPVOID)StartBoundary, MemSize, flAllocationType);

if (newMemory != NULL && pRetVal != NULL)
{
*newMemory = true;
}
}

if (pRetVal != NULL)
Expand Down Expand Up @@ -618,8 +629,11 @@ static LPVOID ReserveVirtualMemory(
#endif // MMAP_ANON_IGNORES_PROTECTION

#ifdef MADV_DONTDUMP
// Do not include reserved memory in coredump.
madvise(pRetVal, MemSize, MADV_DONTDUMP);
// Do not include reserved uncommitted memory in coredump.
if (!(fAllocationType & MEM_COMMIT))
{
madvise(pRetVal, MemSize, MADV_DONTDUMP);
}
#endif

return pRetVal;
Expand All @@ -646,6 +660,7 @@ VIRTUALCommitMemory(
PCMI pInformation = 0;
LPVOID pRetVal = NULL;
BOOL IsLocallyReserved = FALSE;
BOOL IsNewMemory = FALSE;
INT nProtect;

if ( lpAddress )
Expand All @@ -668,7 +683,7 @@ VIRTUALCommitMemory(
*/
LPVOID pReservedMemory =
VIRTUALReserveMemory( pthrCurrent, lpAddress, dwSize,
flAllocationType, flProtect );
flAllocationType, flProtect, &IsNewMemory );

TRACE( "Reserve and commit the memory!\n " );

Expand Down Expand Up @@ -710,8 +725,11 @@ VIRTUALCommitMemory(
}

#ifdef MADV_DODUMP
// Include committed memory in coredump.
madvise((void *) StartBoundary, MemSize, MADV_DODUMP);
// Include committed memory in coredump. Any newly allocated memory included by default.
if (!IsNewMemory)
{
madvise((void *) StartBoundary, MemSize, MADV_DODUMP);
}
#endif

pRetVal = (void *) StartBoundary;
Expand Down