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- meminfo:
- Provides information about distribution and utilization of memory. This
- varies by architecture and compile options. The following is from a
- 16GB PIII, which has highmem enabled. You may not have all of these fields.
- > cat /proc/meminfo
- MemTotal: 16344972 kB
- MemFree: 13634064 kB
- Buffers: 3656 kB
- Cached: 1195708 kB
- SwapCached: 0 kB
- Active: 891636 kB
- Inactive: 1077224 kB
- HighTotal: 15597528 kB
- HighFree: 13629632 kB
- LowTotal: 747444 kB
- LowFree: 4432 kB
- SwapTotal: 0 kB
- SwapFree: 0 kB
- Dirty: 968 kB
- Writeback: 0 kB
- AnonPages: 861800 kB
- Mapped: 280372 kB
- Slab: 284364 kB
- SReclaimable: 159856 kB
- SUnreclaim: 124508 kB
- PageTables: 24448 kB
- NFS_Unstable: 0 kB
- Bounce: 0 kB
- WritebackTmp: 0 kB
- CommitLimit: 7669796 kB
- Committed_AS: 100056 kB
- VmallocTotal: 112216 kB
- VmallocUsed: 428 kB
- VmallocChunk: 111088 kB
- MemTotal: Total usable ram (i.e. physical ram minus a few reserved
- bits and the kernel binary code)
- MemFree: The sum of LowFree+HighFree
- Buffers: Relatively temporary storage for raw disk blocks
- shouldn't get tremendously large (20MB or so)
- Cached: in-memory cache for files read from the disk (the
- pagecache). Doesn't include SwapCached
- SwapCached: Memory that once was swapped out, is swapped back in but
- still also is in the swapfile (if memory is needed it
- doesn't need to be swapped out AGAIN because it is already
- in the swapfile. This saves I/O)
- Active: Memory that has been used more recently and usually not
- reclaimed unless absolutely necessary.
- Inactive: Memory which has been less recently used. It is more
- eligible to be reclaimed for other purposes
- HighTotal:
- HighFree: Highmem is all memory above ~860MB of physical memory
- Highmem areas are for use by userspace programs, or
- for the pagecache. The kernel must use tricks to access
- this memory, making it slower to access than lowmem.
- LowTotal:
- LowFree: Lowmem is memory which can be used for everything that
- highmem can be used for, but it is also available for the
- kernel's use for its own data structures. Among many
- other things, it is where everything from the Slab is
- allocated. Bad things happen when you're out of lowmem.
- SwapTotal: total amount of swap space available
- SwapFree: Memory which has been evicted from RAM, and is temporarily
- on the disk
- Dirty: Memory which is waiting to get written back to the disk
- Writeback: Memory which is actively being written back to the disk
- AnonPages: Non-file backed pages mapped into userspace page tables
- Mapped: files which have been mmaped, such as libraries
- Slab: in-kernel data structures cache
- SReclaimable: Part of Slab, that might be reclaimed, such as caches
- SUnreclaim: Part of Slab, that cannot be reclaimed on memory pressure
- PageTables: amount of memory dedicated to the lowest level of page
- tables.
- NFS_Unstable: NFS pages sent to the server, but not yet committed to stable
- storage
- Bounce: Memory used for block device "bounce buffers"
- WritebackTmp: Memory used by FUSE for temporary writeback buffers
- CommitLimit: Based on the overcommit ratio ('vm.overcommit_ratio'),
- this is the total amount of memory currently available to
- be allocated on the system. This limit is only adhered to
- if strict overcommit accounting is enabled (mode 2 in
- 'vm.overcommit_memory').
- The CommitLimit is calculated with the following formula:
- CommitLimit = ('vm.overcommit_ratio' * Physical RAM) + Swap
- For example, on a system with 1G of physical RAM and 7G
- of swap with a `vm.overcommit_ratio` of 30 it would
- yield a CommitLimit of 7.3G.
- For more details, see the memory overcommit documentation
- in vm/overcommit-accounting.
- Committed_AS: The amount of memory presently allocated on the system.
- The committed memory is a sum of all of the memory which
- has been allocated by processes, even if it has not been
- "used" by them as of yet. A process which malloc()'s 1G
- of memory, but only touches 300M of it will only show up
- as using 300M of memory even if it has the address space
- allocated for the entire 1G. This 1G is memory which has
- been "committed" to by the VM and can be used at any time
- by the allocating application. With strict overcommit
- enabled on the system (mode 2 in 'vm.overcommit_memory'),
- allocations which would exceed the CommitLimit (detailed
- above) will not be permitted. This is useful if one needs
- to guarantee that processes will not fail due to lack of
- memory once that memory has been successfully allocated.
- VmallocTotal: total size of vmalloc memory area
- VmallocUsed: amount of vmalloc area which is used
- VmallocChunk: largest contiguous block of vmalloc area which is free
- ..............................................................................
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