9cfe015aa4
NR_OPEN (historically set to 1024*1024) actually forbids processes to open more than 1024*1024 handles. Unfortunatly some production servers hit the not so 'ridiculously high value' of 1024*1024 file descriptors per process. Changing NR_OPEN is not considered safe because of vmalloc space potential exhaust. This patch introduces a new sysctl (/proc/sys/fs/nr_open) wich defaults to 1024*1024, so that admins can decide to change this limit if their workload needs it. [akpm@linux-foundation.org: export it for sparc64] Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: "David S. Miller" <davem@davemloft.net> Cc: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
180 lines
6.2 KiB
Text
180 lines
6.2 KiB
Text
Documentation for /proc/sys/fs/* kernel version 2.2.10
|
|
(c) 1998, 1999, Rik van Riel <riel@nl.linux.org>
|
|
|
|
For general info and legal blurb, please look in README.
|
|
|
|
==============================================================
|
|
|
|
This file contains documentation for the sysctl files in
|
|
/proc/sys/fs/ and is valid for Linux kernel version 2.2.
|
|
|
|
The files in this directory can be used to tune and monitor
|
|
miscellaneous and general things in the operation of the Linux
|
|
kernel. Since some of the files _can_ be used to screw up your
|
|
system, it is advisable to read both documentation and source
|
|
before actually making adjustments.
|
|
|
|
Currently, these files are in /proc/sys/fs:
|
|
- dentry-state
|
|
- dquot-max
|
|
- dquot-nr
|
|
- file-max
|
|
- file-nr
|
|
- inode-max
|
|
- inode-nr
|
|
- inode-state
|
|
- nr_open
|
|
- overflowuid
|
|
- overflowgid
|
|
- suid_dumpable
|
|
- super-max
|
|
- super-nr
|
|
|
|
Documentation for the files in /proc/sys/fs/binfmt_misc is
|
|
in Documentation/binfmt_misc.txt.
|
|
|
|
==============================================================
|
|
|
|
dentry-state:
|
|
|
|
From linux/fs/dentry.c:
|
|
--------------------------------------------------------------
|
|
struct {
|
|
int nr_dentry;
|
|
int nr_unused;
|
|
int age_limit; /* age in seconds */
|
|
int want_pages; /* pages requested by system */
|
|
int dummy[2];
|
|
} dentry_stat = {0, 0, 45, 0,};
|
|
--------------------------------------------------------------
|
|
|
|
Dentries are dynamically allocated and deallocated, and
|
|
nr_dentry seems to be 0 all the time. Hence it's safe to
|
|
assume that only nr_unused, age_limit and want_pages are
|
|
used. Nr_unused seems to be exactly what its name says.
|
|
Age_limit is the age in seconds after which dcache entries
|
|
can be reclaimed when memory is short and want_pages is
|
|
nonzero when shrink_dcache_pages() has been called and the
|
|
dcache isn't pruned yet.
|
|
|
|
==============================================================
|
|
|
|
dquot-max & dquot-nr:
|
|
|
|
The file dquot-max shows the maximum number of cached disk
|
|
quota entries.
|
|
|
|
The file dquot-nr shows the number of allocated disk quota
|
|
entries and the number of free disk quota entries.
|
|
|
|
If the number of free cached disk quotas is very low and
|
|
you have some awesome number of simultaneous system users,
|
|
you might want to raise the limit.
|
|
|
|
==============================================================
|
|
|
|
file-max & file-nr:
|
|
|
|
The kernel allocates file handles dynamically, but as yet it
|
|
doesn't free them again.
|
|
|
|
The value in file-max denotes the maximum number of file-
|
|
handles that the Linux kernel will allocate. When you get lots
|
|
of error messages about running out of file handles, you might
|
|
want to increase this limit.
|
|
|
|
The three values in file-nr denote the number of allocated
|
|
file handles, the number of unused file handles and the maximum
|
|
number of file handles. When the allocated file handles come
|
|
close to the maximum, but the number of unused file handles is
|
|
significantly greater than 0, you've encountered a peak in your
|
|
usage of file handles and you don't need to increase the maximum.
|
|
|
|
==============================================================
|
|
|
|
nr_open:
|
|
|
|
This denotes the maximum number of file-handles a process can
|
|
allocate. Default value is 1024*1024 (1048576) which should be
|
|
enough for most machines. Actual limit depends on RLIMIT_NOFILE
|
|
resource limit.
|
|
|
|
==============================================================
|
|
|
|
inode-max, inode-nr & inode-state:
|
|
|
|
As with file handles, the kernel allocates the inode structures
|
|
dynamically, but can't free them yet.
|
|
|
|
The value in inode-max denotes the maximum number of inode
|
|
handlers. This value should be 3-4 times larger than the value
|
|
in file-max, since stdin, stdout and network sockets also
|
|
need an inode struct to handle them. When you regularly run
|
|
out of inodes, you need to increase this value.
|
|
|
|
The file inode-nr contains the first two items from
|
|
inode-state, so we'll skip to that file...
|
|
|
|
Inode-state contains three actual numbers and four dummies.
|
|
The actual numbers are, in order of appearance, nr_inodes,
|
|
nr_free_inodes and preshrink.
|
|
|
|
Nr_inodes stands for the number of inodes the system has
|
|
allocated, this can be slightly more than inode-max because
|
|
Linux allocates them one pageful at a time.
|
|
|
|
Nr_free_inodes represents the number of free inodes (?) and
|
|
preshrink is nonzero when the nr_inodes > inode-max and the
|
|
system needs to prune the inode list instead of allocating
|
|
more.
|
|
|
|
==============================================================
|
|
|
|
overflowgid & overflowuid:
|
|
|
|
Some filesystems only support 16-bit UIDs and GIDs, although in Linux
|
|
UIDs and GIDs are 32 bits. When one of these filesystems is mounted
|
|
with writes enabled, any UID or GID that would exceed 65535 is translated
|
|
to a fixed value before being written to disk.
|
|
|
|
These sysctls allow you to change the value of the fixed UID and GID.
|
|
The default is 65534.
|
|
|
|
==============================================================
|
|
|
|
suid_dumpable:
|
|
|
|
This value can be used to query and set the core dump mode for setuid
|
|
or otherwise protected/tainted binaries. The modes are
|
|
|
|
0 - (default) - traditional behaviour. Any process which has changed
|
|
privilege levels or is execute only will not be dumped
|
|
1 - (debug) - all processes dump core when possible. The core dump is
|
|
owned by the current user and no security is applied. This is
|
|
intended for system debugging situations only. Ptrace is unchecked.
|
|
2 - (suidsafe) - any binary which normally would not be dumped is dumped
|
|
readable by root only. This allows the end user to remove
|
|
such a dump but not access it directly. For security reasons
|
|
core dumps in this mode will not overwrite one another or
|
|
other files. This mode is appropriate when administrators are
|
|
attempting to debug problems in a normal environment.
|
|
|
|
==============================================================
|
|
|
|
super-max & super-nr:
|
|
|
|
These numbers control the maximum number of superblocks, and
|
|
thus the maximum number of mounted filesystems the kernel
|
|
can have. You only need to increase super-max if you need to
|
|
mount more filesystems than the current value in super-max
|
|
allows you to.
|
|
|
|
==============================================================
|
|
|
|
aio-nr & aio-max-nr:
|
|
|
|
aio-nr shows the current system-wide number of asynchronous io
|
|
requests. aio-max-nr allows you to change the maximum value
|
|
aio-nr can grow to.
|
|
|
|
==============================================================
|