Re: [RFC][PATCH 3/3] memcg documenation soft limit (Yet Another One)

[Randy Dunlap <randy.dunlap@oracle.com>]

KAMEZAWA Hiroyuki wrote:
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> 
> Documentation for softlimit (3/3)
> 
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> ---
>  Documentation/cgroups/memory.txt |   19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> Index: mmotm-2.6.29-Mar3/Documentation/cgroups/memory.txt
> ===================================================================
> --- mmotm-2.6.29-Mar3.orig/Documentation/cgroups/memory.txt
> +++ mmotm-2.6.29-Mar3/Documentation/cgroups/memory.txt
> @@ -322,6 +322,25 @@ will be charged as a new owner of it.
>    - a cgroup which uses hierarchy and it has child cgroup.
>    - a cgroup which uses hierarchy and not the root of hierarchy.
>  
> +5.4 softlimit
> +  Memory cgroup supports softlimit and has 2 params for control.

                                                parameters

> +    - memory.softlimit_in_bytes
> +	- softlimit to this cgroup.
         softlimit for this cgroup
		(i.e., no beginning '-' and no ending '.')


> +    - memory.softlimit_priority.
> +	- priority of this cgroup at softlimit reclaim.
	 priority of this cgroup at softlimit reclaim

> +	  Allowed priority level is 3-0 and 3 is the lowest.

	Not very user friendly...

> +	  If 0, this cgroup will not be target of softlimit.
> +
> +  At memory shortage of the system (or local node/zone), softlimit helps
> +  kswapd(), a global memory recalim kernel thread, and inform victim cgroup

                               reclaim                    informs

> +  to be shrinked to kswapd.
> +
> +  Victim selection logic:
> +  The kernel searches from the lowest priroty(3) up to the highest(1).

                                         priority                     0 ?? (from above)

> +  If it find a cgroup witch has memory larger than softlimit, steal memory

           finds         which

> +  from it.
> +  If multiple cgroups are on the same priority, each cgroup wil be a

                                                               will

> +  victim in turn.
>  
>  6. Hierarchy support


-- 
~Randy