diff options
| author | K. Y. Srinivasan <kys@microsoft.com> | 2012-11-15 14:34:42 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-11-15 15:41:22 -0800 |
| commit | 997071bcb34005f42e0fe5bc7930e895b070f251 (patch) | |
| tree | 7cc8056370e1c77314fdf0b3fd72bcc69743f24c /mm/mmap.c | |
| parent | d892de8d3fb1e807de561289cfb1fed42950440a (diff) | |
mm: export a function to get vm committed memory
It will be useful to be able to access global memory commitment from
device drivers. On the Hyper-V platform, the host has a policy engine to
balance the available physical memory amongst all competing virtual
machines hosted on a given node. This policy engine is driven by a number
of metrics including the memory commitment reported by the guests. The
balloon driver for Linux on Hyper-V will use this function to retrieve
guest memory commitment. This function is also used in Xen self
ballooning code.
[akpm@linux-foundation.org: coding-style tweak]
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm/mmap.c')
| -rw-r--r-- | mm/mmap.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index 2d942353d681..b064822be82e 100644 --- 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 * succeed and -ENOMEM implies there is not. |