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

[David Rientjes]

On Wed, 26 Sep 2007, Balbir Singh wrote:

> Yes, I prefer 0 as well and had that in a series in the Lost World
> of my earlier memory/RSS controller patches. I feel now that 0 is
> a bit confusing, we don't use 0 to mean unlimited, unless we
> treat the memory.limit_in_bytes value as boolean. 0 is false,
> meaning there is no limit, > 0 is true, which means the limit
> is set and the value is specified to the value read out.
> 

I think any user who attaches a task that is still running to cgroup that 
has memory.limit_in_bytes specified as 0 will realize quickly that it's 
not doing anything to limit memory.  0 is the best choice for denoting 
unlimited memory limits.

> > diff --git a/kernel/res_counter.c b/kernel/res_counter.c
> > --- a/kernel/res_counter.c
> > +++ b/kernel/res_counter.c
> > @@ -16,12 +16,15 @@
> >  void res_counter_init(struct res_counter *counter)
> >  {
> >  	spin_lock_init(&counter->lock);
> > -	counter->limit = (unsigned long)LONG_MAX;
> 
> So, we create all containers with infinite limit?
> 

Yeah, since you kzalloc'd the struct mem_cgroup, the struct res_counter 
will also be zero'd and inherently have a limit of 0.  It's far better 
than any arbitrary value you're going to give them, unless they inherit 
the value of their parent.

> >  }
> > 
> >  int res_counter_charge_locked(struct res_counter *counter, unsigned long val)
> >  {
> > -	if (counter->usage + val > counter->limit) {
> > +	/*
> > +	 * If 'memory.limit' is set to 0, there is no charge to this
> 
> nit pick, should be memory.limit_in_bytes
> 

This is from a month ago, I'm assuming more has changed than just the name 
here :)
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