Re: [RFC][PATCH] memcg documentaion update

[Greg Thelen <gthelen@google.com>]

On Sun, Mar 28, 2010 at 11:42 PM, KAMEZAWA Hiroyuki
<kamezawa.hiroyu@jp.fujitsu.com> wrote:
>
> At reading Documentation/cgroup/memory.txt, I felt
>
>  - old
>  - hard to find it's supported what I want to do
>
> Hmm..maybe some rewrite will be necessary.
>
> ==
> Documentation update. We have too much files now....
>
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> ---
>  Documentation/cgroups/memory.txt |   48 ++++++++++++++++++++++++++++++---------
>  1 file changed, 38 insertions(+), 10 deletions(-)
>
> Index: mmotm-2.6.34-Mar24/Documentation/cgroups/memory.txt
> ===================================================================
> --- mmotm-2.6.34-Mar24.orig/Documentation/cgroups/memory.txt
> +++ mmotm-2.6.34-Mar24/Documentation/cgroups/memory.txt
> @@ -4,16 +4,6 @@ NOTE: The Memory Resource Controller has
>  to as the memory controller in this document. Do not confuse memory controller
>  used here with the memory controller that is used in hardware.
>
> -Salient features
> -
> -a. Enable control of Anonymous, Page Cache (mapped and unmapped) and
> -   Swap Cache memory pages.
> -b. The infrastructure allows easy addition of other types of memory to control
> -c. Provides *zero overhead* for non memory controller users
> -d. Provides a double LRU: global memory pressure causes reclaim from the
> -   global LRU; a cgroup on hitting a limit, reclaims from the per
> -   cgroup LRU
> -
>  Benefits and Purpose of the memory controller
>
>  The memory controller isolates the memory behaviour of a group of tasks
> @@ -33,6 +23,44 @@ d. A CD/DVD burner could control the amo
>  e. There are several other use cases, find one or use the controller just
>    for fun (to learn and hack on the VM subsystem).
>
> +Current Status: linux-2.6.34-mmotom(2010/March)
> +
> +Features:
> + - accounting anonymous pages, file caches, swap caches usage and limit them.
> + - private LRU and reclaim routine. (system's global LRU and private LRU
> +   work independently from each other)
> + - optionaly, memory+swap usage
> + - hierarchical accounting
> + - softlimit
> + - moving(recharging) account at moving a task
> + - usage threshold notifier
> + - oom-killer disable and oom-notifier
> + - Root cgroup has no limit controls.
> +
> + Kernel memory and Hugepages are not under control yet. We just manage
> + pages on LRU. To add more controls, we have to take care of performance.
> +
> +Brief summary of control files.
> +
> + tasks                         # attach a task(thread)
> + cgroup.procs                  # attach a process(all threads under it)
> + cgroup.event_control          # an interface for event_fd()
> + memory.usage_in_bytes         # show current memory(RSS+Cache) usage.
> + memory.memsw.usage_in_bytes   # show current memory+Swap usage.
> + memory.limit_in_bytes         # set/show limit of memory usage
> + memory.memsw.limit_in_bytes   # set/show limit of memory+Swap usage.
> + memory.failcnt                        # show the number of memory usage hit limits.
> + memory.memsw.failcnt          # show the number of memory+Swap hit limits.
> + memory.max_usage_in_bytes     # show max memory usage recorded.
> + memory.memsw.usage_in_bytes   # show max memory+Swap usage recorded.
> + memory.stat                   # show various statistics.
> + memory.use_hierarchy          # set/show hierarchical account enabled.
> + memory.force_empty            # trigger forced move charge to parent.
> + memory.swappiness             # set/show swappiness parameter of vmscan
> +                                 (See sysctl's vm.swappiness)
> + memory.move_charge_at_immigrate# set/show controls of moving charges
> + memory.oom_control            # set/show oom controls.
> +
>  1. History
>
>  The memory controller has a long history. A request for comments for the memory
>
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Two comments:
1. Should we also include a description of the
memory.soft_limit_in_bytes control file in the "Brief summary"
section?

2. the subject of this thread misspelled "documentation
(s/documentaion/documentation/).  Not a problem, but you might want to
fix it for eventually patch submission.

--
Greg

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