From 997071bcb34005f42e0fe5bc7930e895b070f251 Mon Sep 17 00:00:00 2001 From: "K. Y. Srinivasan" Date: Thu, 15 Nov 2012 14:34:42 -0800 Subject: [PATCH] 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 Acked-by: David Rientjes Acked-by: Dan Magenheimer Cc: Konrad Rzeszutek Wilk Cc: Jeremy Fitzhardinge Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- drivers/xen/xen-selfballoon.c | 2 +- include/linux/mman.h | 2 ++ mm/mmap.c | 14 ++++++++++++++ mm/nommu.c | 15 +++++++++++++++ 4 files changed, 32 insertions(+), 1 deletion(-) diff --git a/drivers/xen/xen-selfballoon.c b/drivers/xen/xen-selfballoon.c index 7d041cb6da26..2552d3e0a70f 100644 --- a/drivers/xen/xen-selfballoon.c +++ b/drivers/xen/xen-selfballoon.c @@ -222,7 +222,7 @@ static void selfballoon_process(struct work_struct *work) 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 --git a/include/linux/mman.h b/include/linux/mman.h index d09dde1e57fb..9aa863da287f 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 vm_memory_committed(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 2d942353d681..b064822be82e 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -88,6 +88,20 @@ 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 diff --git a/mm/nommu.c b/mm/nommu.c index 45131b41bcdb..79c3cac87afa 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -66,6 +66,21 @@ 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); -- 2.20.1