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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>
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@ -222,7 +222,7 @@ static void selfballoon_process(struct work_struct *work)
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if (xen_selfballooning_enabled) {
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cur_pages = totalram_pages;
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tgt_pages = cur_pages; /* default is no change */
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goal_pages = percpu_counter_read_positive(&vm_committed_as) +
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goal_pages = vm_memory_committed() +
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totalreserve_pages +
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MB2PAGES(selfballoon_reserved_mb);
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#ifdef CONFIG_FRONTSWAP
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@ -11,6 +11,8 @@ extern int sysctl_overcommit_memory;
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extern int sysctl_overcommit_ratio;
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extern struct percpu_counter vm_committed_as;
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unsigned long vm_memory_committed(void);
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static inline void vm_acct_memory(long pages)
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{
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percpu_counter_add(&vm_committed_as, pages);
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14
mm/mmap.c
14
mm/mmap.c
@ -88,6 +88,20 @@ int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
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*/
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struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
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/*
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* The global memory commitment made in the system can be a metric
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* that can be used to drive ballooning decisions when Linux is hosted
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* as a guest. On Hyper-V, the host implements a policy engine for dynamically
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* balancing memory across competing virtual machines that are hosted.
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* Several metrics drive this policy engine including the guest reported
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* memory commitment.
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*/
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unsigned long vm_memory_committed(void)
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{
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return percpu_counter_read_positive(&vm_committed_as);
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}
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EXPORT_SYMBOL_GPL(vm_memory_committed);
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/*
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* Check that a process has enough memory to allocate a new virtual
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* mapping. 0 means there is enough memory for the allocation to
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15
mm/nommu.c
15
mm/nommu.c
@ -66,6 +66,21 @@ int heap_stack_gap = 0;
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atomic_long_t mmap_pages_allocated;
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/*
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* The global memory commitment made in the system can be a metric
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* that can be used to drive ballooning decisions when Linux is hosted
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* as a guest. On Hyper-V, the host implements a policy engine for dynamically
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* balancing memory across competing virtual machines that are hosted.
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* Several metrics drive this policy engine including the guest reported
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* memory commitment.
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*/
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unsigned long vm_memory_committed(void)
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{
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return percpu_counter_read_positive(&vm_committed_as);
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}
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EXPORT_SYMBOL_GPL(vm_memory_committed);
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EXPORT_SYMBOL(mem_map);
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EXPORT_SYMBOL(num_physpages);
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