[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Date: Sat, 10 Nov 2012 18:25:28 -0800
From: "K. Y. Srinivasan" <kys@...rosoft.com>
To: gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
devel@...uxdriverproject.org, olaf@...fle.de, apw@...onical.com,
andi@...stfloor.org, akpm@...ux-foundation.org, linux-mm@...ck.org,
kamezawa.hiroyuki@...il.com, mhocko@...e.cz, hannes@...xchg.org,
yinghan@...gle.com
Cc: "K. Y. Srinivasan" <kys@...rosoft.com>
Subject: [PATCH 1/1] mm: Export a function to read vm_committed_as
It may be useful to be able to access vm_committed_as 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 pressure reported by the guests. The balloon driver
for Linux on Hyper-V uses this function to report memory pressure back to
the host.
Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
---
include/linux/mman.h | 2 ++
mm/mmap.c | 11 +++++++++++
mm/nommu.c | 11 +++++++++++
3 files changed, 24 insertions(+), 0 deletions(-)
diff --git a/include/linux/mman.h b/include/linux/mman.h
index d09dde1..d53dc3d 100644
--- a/include/linux/mman.h
+++ b/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 read_vm_committed_as(void);
+
static inline void vm_acct_memory(long pages)
{
percpu_counter_add(&vm_committed_as, pages);
diff --git a/mm/mmap.c b/mm/mmap.c
index 2d94235..e527239 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -89,6 +89,17 @@ int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
/*
+ * A wrapper to read vm_committed_as that can be used by external modules.
+ */
+
+unsigned long read_vm_committed_as(void)
+{
+ return percpu_counter_read_positive(&vm_committed_as);
+}
+
+EXPORT_SYMBOL_GPL(read_vm_committed_as);
+
+/*
* 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 --git a/mm/nommu.c b/mm/nommu.c
index 45131b4..dbbd0aa 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -66,6 +66,17 @@ int heap_stack_gap = 0;
atomic_long_t mmap_pages_allocated;
+/*
+ * A wrapper to read vm_committed_as that can be used by external modules.
+ */
+
+unsigned long read_vm_committed_as(void)
+{
+ return percpu_counter_read_positive(&vm_committed_as);
+}
+
+EXPORT_SYMBOL_GPL(read_vm_committed_as);
+
EXPORT_SYMBOL(mem_map);
EXPORT_SYMBOL(num_physpages);
--
1.7.4.1
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists