Re: [RFC][PATCH] allow "unlimited" limit value.

[Balbir Singh <balbir-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>]

KAMEZAWA Hiroyuki wrote:
> just for a RFC.
> 
> When I use memory controller, I notice that memory.limit_in_bytes shows
> just very big number, if unlimited.
> 
> A user(or tool) has to know that the big number(LLONG_MAX) means "unlimted".
> IMHO, some interface which allows users to specify "unlimited" value is helpful.
> 
> This patch tries to define value RES_COUTNER_UNLIMITED (== LLONG_MAX) and
> modifies an interface to support "unlimted" value.
> 
> Because this patch breaks limit_in_bytes to some extent,
> I'm glad if someone has a better idea to show unlimited value.
> (if some easy value means "unlimited", it's helpful. LLONG_MAX is not easy
>  to be recognized.)
> 
> ==after this patch ==
> [root@aworks kamezawa]# echo -n 400000000 > /opt/cgroup/memory.limit_in_bytes
> [root@aworks kamezawa]# cat /opt/cgroup/memory.limit_in_bytes
> 400003072
> [root@aworks kamezawa]# echo -n unlimited > /opt/cgroup/memory.limit_in_bytes
> [root@aworks kamezawa]# cat /opt/cgroup/memory.limit_in_bytes
> unlimited
> 

Hi, Kamezawa-San,

Your changes make sense, but not CLUI (Command Line Usage) sense.
1. The problem is that when we mix strings with numbers, tools that
   parse/use get confused and complicated
2. ULONGLONG_MAX is a real limit, there is no such thing as unlimited.
   If the user does ever go beyond ULONGLONG_MAX, we will limit him :-)

Having said that, I do wish to have a more intuitive interface for
users. May be a perl/python script to hide away the numbers game
from the users. What do you think?


-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL