Modified: trunk/Source/_javascript_Core/ChangeLog (220400 => 220401)
--- trunk/Source/_javascript_Core/ChangeLog 2017-08-08 13:05:22 UTC (rev 220400)
+++ trunk/Source/_javascript_Core/ChangeLog 2017-08-08 13:11:00 UTC (rev 220401)
@@ -1,3 +1,22 @@
+2017-08-06 Yusuke Suzuki <utatane....@gmail.com>
+
+ [Linux] Clear WasmMemory with madvice instead of memset
+ https://bugs.webkit.org/show_bug.cgi?id=175150
+
+ Reviewed by Filip Pizlo.
+
+ In Linux, zeroing pages with memset populates backing store.
+ Instead, we should use madvise with MADV_DONTNEED. It discards
+ pages. And if you access these pages, on-demand-zero-pages will
+ be shown.
+
+ We also commit grown pages in all OSes.
+
+ * wasm/WasmMemory.cpp:
+ (JSC::Wasm::commitZeroPages):
+ (JSC::Wasm::Memory::create):
+ (JSC::Wasm::Memory::grow):
+
2017-08-07 Robin Morisset <rmoris...@apple.com>
GetOwnProperty of TypedArray indexed fields is wrongly configurable
Modified: trunk/Source/_javascript_Core/wasm/WasmMemory.cpp (220400 => 220401)
--- trunk/Source/_javascript_Core/wasm/WasmMemory.cpp 2017-08-08 13:05:22 UTC (rev 220400)
+++ trunk/Source/_javascript_Core/wasm/WasmMemory.cpp 2017-08-08 13:11:00 UTC (rev 220401)
@@ -255,6 +255,21 @@
dataLogLnIf(verbose, "Memory::Memory allocating ", *this);
}
+static void commitZeroPages(void* startAddress, size_t sizeInBytes)
+{
+ bool writable = true;
+ bool executable = false;
+#if OS(LINUX)
+ // In Linux, MADV_DONTNEED clears backing pages with zero. Be Careful that MADV_DONTNEED shows different semantics in different OSes.
+ // For example, FreeBSD does not clear backing pages immediately.
+ while (madvise(startAddress, sizeInBytes, MADV_DONTNEED) == -1 && errno == EAGAIN) { }
+ OSAllocator::commit(startAddress, sizeInBytes, writable, executable);
+#else
+ OSAllocator::commit(startAddress, sizeInBytes, writable, executable);
+ memset(startAddress, 0, sizeInBytes);
+#endif
+}
+
RefPtr<Memory> Memory::create(VM& vm, PageCount initial, PageCount maximum)
{
ASSERT(initial);
@@ -293,16 +308,14 @@
}
if (fastMemory) {
- bool writable = true;
- bool executable = false;
- OSAllocator::commit(fastMemory, initialBytes, writable, executable);
if (mprotect(fastMemory + initialBytes, Memory::fastMappedBytes() - initialBytes, PROT_NONE)) {
dataLog("mprotect failed: ", strerror(errno), "\n");
RELEASE_ASSERT_NOT_REACHED();
}
+
+ commitZeroPages(fastMemory, initialBytes);
- memset(fastMemory, 0, initialBytes);
return adoptRef(new Memory(fastMemory, initial, maximum, Memory::fastMappedBytes(), MemoryMode::Signaling));
}
@@ -400,7 +413,7 @@
dataLogLnIf(verbose, "Memory::grow in-place failed ", *this);
return false;
}
- memset(startAddress, 0, extraBytes);
+ commitZeroPages(startAddress, extraBytes);
m_size = desiredSize;
return true;
} }
