linux.git/Documentation/sysctl/vm.txt, branch v2.6.29

Update of Documentation: vm.txt and proc.txt

2009-01-16T00:39:35+00:00

Update Documentation/sysctl/vm.txt and Documentation/filesystems/proc.txt.
 More specifically, the section on /proc/sys/vm in
Documentation/filesystems/proc.txt was removed and a link to
Documentation/sysctl/vm.txt added.

Most of the verbiage from proc.txt was simply moved in vm.txt, with new
addtional text for "swappiness" and "stat_interval".

Signed-off-by: Peter W Morreale 
Acked-by: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

NOMMU: Make mmap allocation page trimming behaviour configurable.

2009-01-08T12:04:47+00:00

NOMMU mmap allocates a piece of memory for an mmap that's rounded up in size to
the nearest power-of-2 number of pages.  Currently it then discards the excess
pages back to the page allocator, making that memory available for use by other
things.  This can, however, cause greater amount of fragmentation.

To counter this, a sysctl is added in order to fine-tune the trimming
behaviour.  The default behaviour remains to trim pages aggressively, while
this can either be disabled completely or set to a higher page-granular
watermark in order to have finer-grained control.

vm region vm_top bits taken from an earlier patch by David Howells.

Signed-off-by: Paul Mundt 
Signed-off-by: David Howells 
Tested-by: Mike Frysinger

mm: add dirty_background_bytes and dirty_bytes sysctls

2009-01-06T23:59:03+00:00

This change introduces two new sysctls to /proc/sys/vm:
dirty_background_bytes and dirty_bytes.

dirty_background_bytes is the counterpart to dirty_background_ratio and
dirty_bytes is the counterpart to dirty_ratio.

With growing memory capacities of individual machines, it's no longer
sufficient to specify dirty thresholds as a percentage of the amount of
dirtyable memory over the entire system.

dirty_background_bytes and dirty_bytes specify quantities of memory, in
bytes, that represent the dirty limits for the entire system.  If either
of these values is set, its value represents the amount of dirty memory
that is needed to commence either background or direct writeback.

When a `bytes' or `ratio' file is written, its counterpart becomes a
function of the written value.  For example, if dirty_bytes is written to
be 8096, 8K of memory is required to commence direct writeback.
dirty_ratio is then functionally equivalent to 8K / the amount of
dirtyable memory:

	dirtyable_memory = free pages + mapped pages + file cache

	dirty_background_bytes = dirty_background_ratio * dirtyable_memory
		-or-
	dirty_background_ratio = dirty_background_bytes / dirtyable_memory

		AND

	dirty_bytes = dirty_ratio * dirtyable_memory
		-or-
	dirty_ratio = dirty_bytes / dirtyable_memory

Only one of dirty_background_bytes and dirty_background_ratio may be
specified at a time, and only one of dirty_bytes and dirty_ratio may be
specified.  When one sysctl is written, the other appears as 0 when read.

The `bytes' files operate on a page size granularity since dirty limits
are compared with ZVC values, which are in page units.

Prior to this change, the minimum dirty_ratio was 5 as implemented by
get_dirty_limits() although /proc/sys/vm/dirty_ratio would show any user
written value between 0 and 100.  This restriction is maintained, but
dirty_bytes has a lower limit of only one page.

Also prior to this change, the dirty_background_ratio could not equal or
exceed dirty_ratio.  This restriction is maintained in addition to
restricting dirty_background_bytes.  If either background threshold equals
or exceeds that of the dirty threshold, it is implicitly set to half the
dirty threshold.

Acked-by: Peter Zijlstra 
Cc: Dave Chinner 
Cc: Christoph Lameter 
Signed-off-by: David Rientjes 
Cc: Andrea Righi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Documentation cleanup: trivial misspelling, punctuation, and grammar corrections.

2008-07-26T19:00:06+00:00

Cc: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

oom: add sysctl to enable task memory dump

2008-02-07T16:42:19+00:00

Adds a new sysctl, 'oom_dump_tasks', that enables the kernel to produce a
dump of all system tasks (excluding kernel threads) when performing an
OOM-killing.  Information includes pid, uid, tgid, vm size, rss, cpu,
oom_adj score, and name.

This is helpful for determining why there was an OOM condition and which
rogue task caused it.

It is configurable so that large systems, such as those with several
thousand tasks, do not incur a performance penalty associated with dumping
data they may not desire.

If an OOM was triggered as a result of a memory controller, the tasklist
shall be filtered to exclude tasks that are not a member of the same
cgroup.

Cc: Andrea Arcangeli 
Cc: Christoph Lameter 
Cc: Balbir Singh 
Signed-off-by: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/page-writeback: highmem_is_dirtyable option

2008-02-05T17:44:18+00:00

Add vm.highmem_is_dirtyable toggle

A 32 bit machine with HIGHMEM64 enabled running DCC has an MMAPed file of
approximately 2Gb size which contains a hash format that is written
randomly by the dbclean process.  On 2.6.16 this process took a few
minutes.  With lowmem only accounting of dirty ratios, this takes about 12
hours of 100% disk IO, all random writes.

Include a toggle in /proc/sys/vm/highmem_is_dirtyable which can be set to 1 to
add the highmem back to the total available memory count.

[akpm@linux-foundation.org: Fix the CONFIG_DETECT_SOFTLOCKUP=y build]
Signed-off-by: Bron Gondwana 
Cc: Ethan Solomita 
Cc: Peter Zijlstra 
Cc: WU Fengguang 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Documentation: update hugetlb information

2007-12-18T03:28:17+00:00

The hugetlb documentation has gotten a bit out of sync with the current code.
Updated the sysctl file to refer to Documentation/vm/hugetlbpage.txt.  Update
that file to contain the current state of affairs (with the newer named sysctl
in place).

Signed-off-by: Nishanth Aravamudan 
Acked-by: Adam Litke 
Cc: William Lee Irwin III 
Cc: Dave Hansen 
Cc: David Gibson 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

vm.txt: document min_free_pages as critical for correctness

2007-10-17T15:43:06+00:00

min_free_pages is critical for correctness, document it as such.

Signed-off-by: Pavel Machek 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

oom: add oom_kill_allocating_task sysctl

2007-10-17T15:42:46+00:00

Adds a new sysctl, 'oom_kill_allocating_task', which will automatically kill
the OOM-triggering task instead of scanning through the tasklist to find a
memory-hogging target.  This is helpful for systems with an insanely large
number of tasks where scanning the tasklist significantly degrades
performance.

Cc: Andrea Arcangeli 
Acked-by: Christoph Lameter 
Signed-off-by: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

handle kernelcore=: generic

2007-07-17T17:22:59+00:00

This patch adds the kernelcore= parameter for x86.

Once all patches are applied, a new command-line parameter exist and a new
sysctl.  This patch adds the necessary documentation.

From: Yasunori Goto 

  When "kernelcore" boot option is specified, kernel can't boot up on ia64
  because of an infinite loop.  In addition, the parsing code can be handled
  in an architecture-independent manner.

  This patch uses common code to handle the kernelcore= parameter.  It is
  only available to architectures that support arch-independent zone-sizing
  (i.e.  define CONFIG_ARCH_POPULATES_NODE_MAP).  Other architectures will
  ignore the boot parameter.

[bunk@stusta.de: make cmdline_parse_kernelcore() static]
Signed-off-by: Mel Gorman 
Signed-off-by: Yasunori Goto 
Acked-by: Andy Whitcroft 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds