The vmstat files

QNX SDP8.0System ArchitectureDeveloperUser

The vmstat files provide memory usage information for both the system and processes.

System counters

The values of the counters below are the totals of the values of all instances of /proc/pid/vmstat, where pid is the process ID. You can access these values using the /proc/vm/stats file:
cat /proc/vm/stats
vm_aspace
Number of address spaces in the system, which corresponds to the number of active processes
vm_object
Number of file-backed memory objects in the memory cache
vm_shmem
Number of shared objects in the memory cache
vmem_avail

The number of pages that have not been reserved by allocations, and are thus available for new allocations

pmem_xdom_page
Number of times the page allocator had to cross domains
pmem_xdom_contig
Number of times the memory manager page allocator had to aggregate non-contiguous pages
fd_pend_close
Number of file descriptor objects on the closing queue
fd_free_obj
Number of file descriptor objects on the free queue
kmem_vavail
Mapping space available in the kernel
page_count
Number of RAM pages available to the page allocator
cache_object
Amount of memory held in file-backed cache objects
cache_shmem

Amount of memory held in anonymous shared-memory objects

pages_allocated

Amount of physical memory that is allocated but not mapped

pages_mapped

Amount of allocated and mapped memory

pages_free
Number of pages in a free state
pages_kernel
Number of pages used by the kernel for its own purposes. It includes the page-table pages allocated for processes.
pages_reserved

The number of pages that the memory manager knows about, but cannot allocate to processes as regular memory. Such ranges are typically the result of the startup program, which runs before the kernel, reserving memory for special-purpose pools, or as a way to reduce boot time (in which case the memory can be added to the system later).

Process counters

You can access these counters by viewing the /proc/pid/vmstat file, where pid is the process ID:
cat /proc/pid/vmstat
as_stats.vm_region
Number of regions
as_stats.vm_map
Number of map entries
as_stats.map_size
Total size of all regions in the address space
as_stats.map_phys
Number of pages that were mapped using mmap() with the MAP_PHYS flag
as_stats.map_shared
Number of pages that were mapped using mmap() with the MAP_SHARED flag
as_stats.map_private
Number of pages that were mapped using mmap() with the MAP_PRIVATE flag
as_stats.rss

Amount of physical memory mapped by the process (resident set size); this value may be larger than the actual amount of mapped physical memory because it counts every mapped page, even if the process has multiple mappings of the same page

as_stats.anon_rsv
Number of reserved anonymous pages
as_stats.rlimit_data
Number of private anonymous page mappings, regardless of any reservations
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