The patch titled
Subject: mm: export a function to get vm committed memory
has been added to the -mm tree. Its filename is
mm-export-a-function-to-get-vm-committed-memory.patch
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------------------------------------------------------
From: "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx>
Subject: 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.
Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
Cc: Greg KH <greg@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Acked-by: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/xen/xen-selfballoon.c | 2 +-
include/linux/mman.h | 2 ++
mm/mmap.c | 15 +++++++++++++++
mm/nommu.c | 16 ++++++++++++++++
4 files changed, 34 insertions(+), 1 deletion(-)
diff -puN drivers/xen/xen-selfballoon.c~mm-export-a-function-to-get-vm-committed-memory drivers/xen/xen-selfballoon.c
--- a/drivers/xen/xen-selfballoon.c~mm-export-a-function-to-get-vm-committed-memory
+++ a/drivers/xen/xen-selfballoon.c
@@ -222,7 +222,7 @@ static void selfballoon_process(struct w
if (xen_selfballooning_enabled) {
cur_pages = totalram_pages;
tgt_pages = cur_pages; /* default is no change */
- goal_pages = percpu_counter_read_positive(&vm_committed_as) +
+ goal_pages = vm_memory_committed() +
totalreserve_pages +
MB2PAGES(selfballoon_reserved_mb);
#ifdef CONFIG_FRONTSWAP
diff -puN include/linux/mman.h~mm-export-a-function-to-get-vm-committed-memory include/linux/mman.h
--- a/include/linux/mman.h~mm-export-a-function-to-get-vm-committed-memory
+++ a/include/linux/mman.h
@@ -11,6 +11,8 @@ extern int sysctl_overcommit_memory;
extern int sysctl_overcommit_ratio;
extern struct percpu_counter vm_committed_as;
+unsigned long vm_memory_committed(void);
+
static inline void vm_acct_memory(long pages)
{
percpu_counter_add(&vm_committed_as, pages);
diff -puN mm/mmap.c~mm-export-a-function-to-get-vm-committed-memory mm/mmap.c
--- a/mm/mmap.c~mm-export-a-function-to-get-vm-committed-memory
+++ a/mm/mmap.c
@@ -90,6 +90,21 @@ int sysctl_max_map_count __read_mostly =
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.
diff -puN mm/nommu.c~mm-export-a-function-to-get-vm-committed-memory mm/nommu.c
--- a/mm/nommu.c~mm-export-a-function-to-get-vm-committed-memory
+++ a/mm/nommu.c
@@ -66,6 +66,22 @@ int heap_stack_gap = 0;
atomic_long_t mmap_pages_allocated;
+/*
+ * 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);
+
EXPORT_SYMBOL(mem_map);
EXPORT_SYMBOL(num_physpages);
_
Patches currently in -mm which might be from kys@xxxxxxxxxxxxx are
linux-next.patch
mm-export-a-function-to-get-vm-committed-memory.patch
mm-export-a-function-to-get-vm-committed-memory-fix.patch
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