Merge branch 'akpm' (Andrew's patchbomb)

[~shefty/rdma-dev.git] / mm / mmap.c

diff --git a/mm/mmap.c b/mm/mmap.c
index 5646677a96d591f5ab1179473b3f4938d42d0ded..f940062c8d4b7dd50a619663c49fde83b40e3f61 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -89,6 +89,20 @@ int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
  */
 struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
 
+/*
+ * The global memory commitment made in the system can be a metric
+ * that can be used to drive ballooning decisions when Linux is hosted
+ * as a guest. On Hyper-V, the host implements a policy engine for dynamically
+ * balancing memory across competing virtual machines that are hosted.
+ * Several metrics drive this policy engine including the guest reported
+ * memory commitment.
+ */
+unsigned long vm_memory_committed(void)
+{
+       return percpu_counter_read_positive(&vm_committed_as);
+}
+EXPORT_SYMBOL_GPL(vm_memory_committed);
+
 /*
  * Check that a process has enough memory to allocate a new virtual
  * mapping. 0 means there is enough memory for the allocation to