linux/fs
Rik van Riel 34e431b0ae /proc/meminfo: provide estimated available memory
Many load balancing and workload placing programs check /proc/meminfo to
estimate how much free memory is available.  They generally do this by
adding up "free" and "cached", which was fine ten years ago, but is
pretty much guaranteed to be wrong today.

It is wrong because Cached includes memory that is not freeable as page
cache, for example shared memory segments, tmpfs, and ramfs, and it does
not include reclaimable slab memory, which can take up a large fraction
of system memory on mostly idle systems with lots of files.

Currently, the amount of memory that is available for a new workload,
without pushing the system into swap, can be estimated from MemFree,
Active(file), Inactive(file), and SReclaimable, as well as the "low"
watermarks from /proc/zoneinfo.

However, this may change in the future, and user space really should not
be expected to know kernel internals to come up with an estimate for the
amount of free memory.

It is more convenient to provide such an estimate in /proc/meminfo.  If
things change in the future, we only have to change it in one place.

Signed-off-by: Rik van Riel <riel@redhat.com>
Reported-by: Erik Mouw <erik.mouw_2@nxp.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-21 16:19:43 -08:00
..
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ocfs2 ocfs2: fix NULL pointer dereference when dismount and ocfs2rec simultaneously 2014-01-21 16:19:42 -08:00
omfs
openpromfs
proc /proc/meminfo: provide estimated available memory 2014-01-21 16:19:43 -08:00
pstore
qnx4
qnx6
quota
ramfs fs/ramfs: don't use module_init for non-modular core code 2014-01-21 16:19:42 -08:00
reiserfs
romfs
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sysfs
sysv
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udf
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aio.c
anon_inodes.c
attr.c
bad_inode.c
binfmt_aout.c
binfmt_elf.c
binfmt_elf_fdpic.c
binfmt_em86.c
binfmt_flat.c
binfmt_misc.c
binfmt_script.c
binfmt_som.c
bio-integrity.c
bio.c
block_dev.c
buffer.c
char_dev.c
compat.c
compat_binfmt_elf.c
compat_ioctl.c fs/compat_ioctl.c: fix an underflow issue (harmless) 2014-01-21 16:19:42 -08:00
coredump.c
coredump.h
dcache.c
dcookies.c
direct-io.c
drop_caches.c
eventfd.c
eventpoll.c
exec.c
fcntl.c
fhandle.c
file.c
file_table.c
filesystems.c
fs-writeback.c
fs_struct.c
generic_acl.c
inode.c
internal.h
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ioprio.c
Kconfig
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libfs.c
locks.c
Makefile
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mount.h
mpage.c
namei.c
namespace.c
no-block.c
open.c
pipe.c
pnode.c
pnode.h
posix_acl.c posix_acl: uninlining 2014-01-21 16:19:42 -08:00
proc_namespace.c
read_write.c fs/read_write.c:compat_readv(): remove bogus area verify 2014-01-21 16:19:42 -08:00
readdir.c
select.c
seq_file.c
signalfd.c
splice.c
stack.c
stat.c
statfs.c
super.c fs/super.c: fix WARN on alloc_super() fail path 2014-01-21 16:19:42 -08:00
sync.c
timerfd.c
utimes.c
xattr.c
xattr_acl.c