Re: [RFC][PATCH] memcg documentaion update

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Tue, 30 Mar 2010 09:13:03 +0900
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:

> On Mon, 29 Mar 2010 15:42:45 +0900, 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.
> > 
> I agree.
> 
> > ==
> > 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.
> > +
> These changes would be very useful to let users know memcg's features at a glance.
> 
> >  1. History
> >  
> >  The memory controller has a long history. A request for comments for the memory
> > 
> 
> BTW, I think it might be better to update 5.2(stat file) too.
> "mapped_file" and "swap"(sorry, my fault) aren't listed there.
> 
Sure, I'll add.

Thanks,
-Kame


> 
> Thanks,
> Daisuke Nishimura.
> 
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