runtime: add sysNoHugePage

Change-Id: Icccafb896de838256a2ec7c3f385e6cbb2b415fa
Reviewed-on: https://go-review.googlesource.com/c/go/+/447360
Auto-Submit: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/runtime/mem.go

@@ -84,6 +84,13 @@ func sysHugePage(v unsafe.Pointer, n uintptr) {
 	sysHugePageOS(v, n)
 }
 
+// sysNoHugePage does not transition memory regions, but instead provides a
+// hint to the OS that it would be less efficient to back this memory region
+// with pages of a larger size transparently.
+func sysNoHugePage(v unsafe.Pointer, n uintptr) {
+	sysNoHugePageOS(v, n)
+}
+
 // sysFree transitions a memory region from any state to None. Therefore, it
 // returns memory unconditionally. It is used if an out-of-memory error has been
 // detected midway through an allocation or to carve out an aligned section of

src/runtime/mem_aix.go

@@ -38,6 +38,9 @@ func sysUsedOS(v unsafe.Pointer, n uintptr) {
 func sysHugePageOS(v unsafe.Pointer, n uintptr) {
 }
 
+func sysNoHugePageOS(v unsafe.Pointer, n uintptr) {
+}
+
 // Don't split the stack as this function may be invoked without a valid G,
 // which prevents us from allocating more stack.
 //

src/runtime/mem_bsd.go

@@ -36,6 +36,9 @@ func sysUsedOS(v unsafe.Pointer, n uintptr) {
 func sysHugePageOS(v unsafe.Pointer, n uintptr) {
 }
 
+func sysNoHugePageOS(v unsafe.Pointer, n uintptr) {
+}
+
 // Don't split the stack as this function may be invoked without a valid G,
 // which prevents us from allocating more stack.
 //

src/runtime/mem_darwin.go

@@ -36,6 +36,9 @@ func sysUsedOS(v unsafe.Pointer, n uintptr) {
 func sysHugePageOS(v unsafe.Pointer, n uintptr) {
 }
 
+func sysNoHugePageOS(v unsafe.Pointer, n uintptr) {
+}
+
 // Don't split the stack as this function may be invoked without a valid G,
 // which prevents us from allocating more stack.
 //

src/runtime/mem_linux.go

@@ -161,6 +161,10 @@ func sysHugePageOS(v unsafe.Pointer, n uintptr) {
 	}
 }
 
+func sysNoHugePageOS(v unsafe.Pointer, n uintptr) {
+	madvise(v, n, _MADV_NOHUGEPAGE)
+}
+
 // Don't split the stack as this function may be invoked without a valid G,
 // which prevents us from allocating more stack.
 //

src/runtime/mem_sbrk.go

@@ -160,6 +160,9 @@ func sysUsedOS(v unsafe.Pointer, n uintptr) {
 func sysHugePageOS(v unsafe.Pointer, n uintptr) {
 }
 
+func sysNoHugePageOS(v unsafe.Pointer, n uintptr) {
+}
+
 func sysMapOS(v unsafe.Pointer, n uintptr) {
 }
 

src/runtime/mem_windows.go

@@ -94,6 +94,9 @@ func sysUsedOS(v unsafe.Pointer, n uintptr) {
 func sysHugePageOS(v unsafe.Pointer, n uintptr) {
 }
 
+func sysNoHugePageOS(v unsafe.Pointer, n uintptr) {
+}
+
 // Don't split the stack as this function may be invoked without a valid G,
 // which prevents us from allocating more stack.
 //