Adds an interface for asking malloc to release free memory back to the OS.

Change: 127216353

2 files changed, 13 insertions, 0 deletions

diff --git a/tensorflow/core/platform/mem.h b/tensorflow/core/platform/mem.h
index 3383d031d8..8e7a18c55d 100644
--- a/tensorflow/core/platform/mem.h
+++ b/tensorflow/core/platform/mem.h
@@ -37,6 +37,15 @@ namespace port {
 void* aligned_malloc(size_t size, int minimum_alignment);
 void aligned_free(void* aligned_memory);
 
+// Tries to release num_bytes of free memory back to the operating
+// system for reuse.  Use this routine with caution -- to get this
+// memory back may require faulting pages back in by the OS, and
+// that may be slow.
+//
+// Currently, if a malloc implementation does not support this
+// routine, this routine is a no-op.
+void MallocExtension_ReleaseToSystem(std::size_t num_bytes);
+
 // Returns the actual number N of bytes reserved by the malloc for the
 // pointer p.  This number may be equal to or greater than the number
 // of bytes requested when p was allocated.
diff --git a/tensorflow/core/platform/posix/port.cc b/tensorflow/core/platform/posix/port.cc
index 1877dfeddc..c8c57753b7 100644
--- a/tensorflow/core/platform/posix/port.cc
+++ b/tensorflow/core/platform/posix/port.cc
@@ -77,6 +77,10 @@ void* aligned_malloc(size_t size, int minimum_alignment) {
 
 void aligned_free(void* aligned_memory) { free(aligned_memory); }
 
+void MallocExtension_ReleaseToSystem(std::size_t num_bytes) {
+  // No-op.
+}
+
 std::size_t MallocExtension_GetAllocatedSize(const void* p) { return 0; }
 
 void AdjustFilenameForLogging(string* filename) {