linux-toradex.git/Documentation/cgroups, branch tegra-9.12.15

cgroups: update documentation of cgroups tasks and procs files

2009-10-08T14:36:39+00:00

Update documentation of cgroups tasks and procs files

Document the cgroup.procs file.

Clarify the semantics of the cgroup.procs and tasks files.  Although the
current cgroup.procs interface returns a sorted and uniqified list of
pids, potential future performance enhancements could result in those
properties being removed - explicitly document this aspect of the API.

There are no existing users of cgroup.procs, so compatibility isn't an
issue.  There are users of the "tasks" file, but none that would appear to
break in the event of the sorted property being broken.  The standard
"libcpuset" explicitly sorts the results of reading from the tasks file,
and "libcg" and other users don't appear to care about ordering.

Signed-off-by: Paul Menage 
Reviewed-by: Li Zefan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memory controller: soft limit documentation

2009-09-24T14:20:59+00:00

Soft limits is a new feature for the memory resource controller, something
similar has existed in the group scheduler in the form of shares.  The CPU
controllers interpretation of shares is very different though.

Soft limits are the most useful feature to have for environments where the
administrator wants to overcommit the system, such that only on memory
contention do the limits become active.  The current soft limits
implementation provides a soft_limit_in_bytes interface for the memory
controller and not for memory+swap controller.  The implementation
maintains an RB-Tree of groups that exceed their soft limit and starts
reclaiming from the group that exceeds this limit by the maximum amount.

This patch:

Add documentation for soft limits

Signed-off-by: Balbir Singh 
Cc: KAMEZAWA Hiroyuki 
Cc: Li Zefan 
Cc: KOSAKI Motohiro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: remove the overhead associated with the root cgroup

2009-09-24T14:20:58+00:00

Change the memory cgroup to remove the overhead associated with accounting
all pages in the root cgroup.  As a side-effect, we can no longer set a
memory hard limit in the root cgroup.

A new flag to track whether the page has been accounted or not has been
added as well.  Flags are now set atomically for page_cgroup,
pcg_default_flags is now obsolete and removed.

[akpm@linux-foundation.org: fix a few documentation glitches]
Signed-off-by: Balbir Singh 
Signed-off-by: Daisuke Nishimura 
Reviewed-by: KAMEZAWA Hiroyuki 
Cc: Daisuke Nishimura 
Cc: Li Zefan 
Cc: Paul Menage 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time

2009-09-24T14:20:58+00:00

Alter the ss->can_attach and ss->attach functions to be able to deal with
a whole threadgroup at a time, for use in cgroup_attach_proc.  (This is a
pre-patch to cgroup-procs-writable.patch.)

Currently, new mode of the attach function can only tell the subsystem
about the old cgroup of the threadgroup leader.  No subsystem currently
needs that information for each thread that's being moved, but if one were
to be added (for example, one that counts tasks within a group) this bit
would need to be reworked a bit to tell the subsystem the right
information.

[hidave.darkstar@gmail.com: fix build]
Signed-off-by: Ben Blum 
Signed-off-by: Paul Menage 
Acked-by: Li Zefan 
Reviewed-by: Matt Helsley 
Cc: "Eric W. Biederman" 
Cc: Oleg Nesterov 
Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: Dave Young 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroups: support named cgroups hierarchies

2009-09-24T14:20:57+00:00

To simplify referring to cgroup hierarchies in mount statements, and to
allow disambiguation in the presence of empty hierarchies and
multiply-bindable subsystems this patch adds support for naming a new
cgroup hierarchy via the "name=" mount option

A pre-existing hierarchy may be specified by either name or by subsystems;
a hierarchy's name cannot be changed by a remount operation.

Example usage:

# To create a hierarchy called "foo" containing the "cpu" subsystem
mount -t cgroup -oname=foo,cpu cgroup /mnt/cgroup1

# To mount the "foo" hierarchy on a second location
mount -t cgroup -oname=foo cgroup /mnt/cgroup2

Signed-off-by: Paul Menage 
Reviewed-by: Li Zefan 
Cc: KAMEZAWA Hiroyuki 
Cc: Balbir Singh 
Cc: Dhaval Giani 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cpusets: document adding/removing cpus to cpuset elaborately

2009-07-01T01:56:01+00:00

By writing a tasks's pid to the file, a process adds that task to that
cgroup/cpuset.  But to add a cpu/mem to a cpuset, the new list of cpus
should be written to the cpuset.mems file which would replace the old list
of cpus.  Make this clearer in the documentation.

Signed-off-by: Nikanth Karthikesan 
Signed-off-by: Li Zefan 
Acked-by: Paul Menage 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: add interface to reset limits

2009-06-18T20:03:48+00:00

We don't have an interface to reset mem.limit or memsw.limit now.

This patch allows to reset mem.limit or memsw.limit when they are being
set to -1.

Signed-off-by: Daisuke Nishimura 
Cc: KAMEZAWA Hiroyuki 
Cc: Balbir Singh 
Cc: Li Zefan 
Cc: Dhaval Giani 
Cc: YAMAMOTO Takashi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: fix behavior under memory.limit equals to memsw.limit

2009-06-18T20:03:48+00:00

A user can set memcg.limit_in_bytes == memcg.memsw.limit_in_bytes when the
user just want to limit the total size of applications, in other words,
not very interested in memory usage itself.  In this case, swap-out will
be done only by global-LRU.

But, under current implementation, memory.limit_in_bytes is checked at
first and try_to_free_page() may do swap-out.  But, that swap-out is
useless for memsw.limit_in_bytes and the thread may hit limit again.

This patch tries to fix the current behavior at memory.limit ==
memsw.limit case.  And documentation is updated to explain the behavior of
this special case.

Signed-off-by: KAMEZAWA Hiroyuki 
Cc: Daisuke Nishimura 
Cc: Balbir Singh 
Cc: Li Zefan 
Cc: Dhaval Giani 
Cc: YAMAMOTO Takashi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: fix documentation

2009-04-13T22:04:33+00:00

The description about various statistics from memory.stat is not accurate
and confusing at times.

Correct this along with a few other minor cleanups.

Signed-off-by: Bharata B Rao 
Acked-by: Balbir Singh 
Acked-by: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

res_counter: update documentation

2009-04-13T22:04:30+00:00

After the introduction of resource counters hierarchies
(28dbc4b6a01fb579a9441c7b81e3d3413dc452df) the prototypes of
res_counter_init() and res_counter_charge() have been changed.

Keep the documentation consistent with the actual function prototypes.

Signed-off-by: Andrea Righi 
Cc: Paul Menage 
Cc: Pavel Emelyanov 
Cc: Balbir Singh 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds