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[v18.x backport] child_process: improve spawn performance on Linux #50098

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2 changes: 1 addition & 1 deletion common.gypi
Original file line number Diff line number Diff line change
Expand Up @@ -36,7 +36,7 @@

# Reset this number to 0 on major V8 upgrades.
# Increment by one for each non-official patch applied to deps/v8.
'v8_embedder_string': '-node.26',
'v8_embedder_string': '-node.27',

##### V8 defaults for Node.js #####

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14 changes: 14 additions & 0 deletions deps/v8/BUILD.gn
Original file line number Diff line number Diff line change
Expand Up @@ -82,6 +82,17 @@ declare_args() {
# Sets -dENABLE_HUGEPAGE
v8_enable_hugepage = false

# Sets -dV8_ENABLE_PRIVATE_MAPPING_FORK_OPTIMIZATION.
#
# This flag speeds up the performance of fork/execve on Linux systems for
# embedders which use it (like Node.js). It works by marking the pages that
# V8 allocates as MADV_DONTFORK. Without MADV_DONTFORK, the Linux kernel
# spends a long time manipulating page mappings on fork and exec which the
# child process doesn't generally need to access.
#
# See v8:7381 for more details.
v8_enable_private_mapping_fork_optimization = false

# Sets -dENABLE_HANDLE_ZAPPING.
v8_enable_handle_zapping = !is_on_release_branch || is_debug

Expand Down Expand Up @@ -862,6 +873,9 @@ config("features") {
if (v8_enable_hugepage) {
defines += [ "ENABLE_HUGEPAGE" ]
}
if (v8_enable_private_mapping_fork_optimization) {
defines += [ "V8_ENABLE_PRIVATE_MAPPING_FORK_OPTIMIZATION" ]
}
if (v8_enable_object_print) {
defines += [ "OBJECT_PRINT" ]
}
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6 changes: 6 additions & 0 deletions deps/v8/src/base/platform/platform-posix.cc
Original file line number Diff line number Diff line change
Expand Up @@ -174,6 +174,12 @@ void* Allocate(void* hint, size_t size, OS::MemoryPermission access,
int flags = GetFlagsForMemoryPermission(access, page_type);
void* result = mmap(hint, size, prot, flags, kMmapFd, kMmapFdOffset);
if (result == MAP_FAILED) return nullptr;

#if V8_ENABLE_PRIVATE_MAPPING_FORK_OPTIMIZATION
// This is advisory, so we ignore errors.
madvise(result, size, MADV_DONTFORK);
#endif

#if ENABLE_HUGEPAGE
if (result != nullptr && size >= kHugePageSize) {
const uintptr_t huge_start =
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17 changes: 17 additions & 0 deletions tools/v8_gypfiles/features.gypi
Original file line number Diff line number Diff line change
Expand Up @@ -68,6 +68,20 @@
}, {
'v8_enable_system_instrumentation': 0,
}],
['OS=="linux"', {
# Sets -dV8_ENABLE_PRIVATE_MAPPING_FORK_OPTIMIZATION.
#
# This flag speeds up the performance of fork/execve on Linux systems for
# embedders which use it (like Node.js). It works by marking the pages that
# V8 allocates as MADV_DONTFORK. Without MADV_DONTFORK, the Linux kernel
# spends a long time manipulating page mappings on fork and exec which the
# child process doesn't generally need to access.
#
# See v8:7381 for more details.
'v8_enable_private_mapping_fork_optimization': 1,
}, {
'v8_enable_private_mapping_fork_optimization': 0,
}],
],
'is_debug%': 0,

Expand Down Expand Up @@ -310,6 +324,9 @@
['v8_enable_hugepage==1', {
'defines': ['ENABLE_HUGEPAGE',],
}],
['v8_enable_private_mapping_fork_optimization==1', {
'defines': ['V8_ENABLE_PRIVATE_MAPPING_FORK_OPTIMIZATION'],
}],
['v8_enable_vtunejit==1', {
'defines': ['ENABLE_VTUNE_JIT_INTERFACE',],
}],
Expand Down
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