Re: [RFC] How to handle the rules engine for cgroups

[David Collier-Brown <davecb@sun.com>]

Vivek Goyal wrote:
> If admin has decided to group applications and has written the rules for
> it then applications should not know anything about grouping. So I think
> application writing an script for being placed into the right group should
> be out of question. Now how does an admin write a wrapper around existing
> application without breaking anything else.

In the Solaris world, processes are placed into cgroups (projects) by
one of two mechanisms:

1) inheritance, with everything I create in my existing project.
   To get this started, there is a mechanism under login/getty/whatever 
   reading the /etc/projects file and, for example, tossing user davecb 
   into a "user.davecb" project.

2) explicit placement with newtask, which starts a program or moves
   a process into a project/cgroup

I have a "bg" project which I use for limiting resource consumption of
background jobs, and a background command which either starts or moves
jobs, thusly:

 case "$1" in
 [0-9]*) # It's a pid
         newtask -p bg -c $1
         ;;
  *) # It's a command-line
         newtask -p bg "$@" &
         ;;
  esac

A rules engine would be more useful for managing workloads once
they're assigned, as IBM does on the mainframe with WLM and goal-directed
resource management. (They're brilliant in this area, by the way, so
I'd be inclined to steal ideas from them  (;-))

--dave
-- 
David Collier-Brown            | Always do right. This will gratify
Sun Microsystems, Toronto      | some people and astonish the rest
davecb@sun.com                 |                      -- Mark Twain
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