Re: [ckrm-tech] [RFC][PATCH] UBC: user resource beancounters

[Chandra Seetharaman <sekharan@us.ibm.com>]

On Thu, 2006-08-24 at 12:10 +0100, Alan Cox wrote:
> Ar Mer, 2006-08-23 am 19:04 -0700, ysgrifennodd Chandra Seetharaman:
> > > A single centralized structure that has fields that are mostly used by
> > > every one should be okay I think.
> > 
> > You mean to say definition like
> > 
> > struct user_beancounter {
> > 	fields;/* fields that exists now */
> > 	
> > 	int kmemsize_ctlr_info1;
> > 	char *kmemsize_ctlr_info2;
> > 
> > 	char *oomguar_ctlr_info1;
> > 	char *oomguar_ctlr_info2;
> > 
> > 	/* and so on */
> > }
> > 
> > is the right thing to do ? even though oomguar controller doesn't care
> > about kmemsize_ctlr_info* etc.,
> 
> 
> All you need is
> 
> struct wombat_controller
> {
> 	struct user_beancounter counter;
> 	void (*wombat_pest_control)(struct wombat *w);
> 	atomic_t wombat_population;
> 	int (*wombat_destructor)(struct wombat *w);
> };

This may not solve the problem, as 
 - we won't be able get the controller data structure given the
   beancounter data structure. 
 - we need to keep the data in sync (since there are multiple copies).
 - we will be copying the whole beancounter data structure needlessly
   (the controller might care only about _its_ parameters).

I agree with you that this can be added later when needed. The problem I
see is that this might need some change in the core data structure which
might face more resistance (than it does now :) once it is in mainline.

> 
> and just embed the counter in whatever you are controlling. The point of
> the beancounters themselves is to be *SIMPLE*. It's unfortunate that
> some folk seem obsessed with extending them for a million theoretical
> projects rather than getting them in and working and then extending them
> for real projects. Please lets not have another EVMS.
> 
> Alan
> 
-- 

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    Chandra Seetharaman               | Be careful what you choose....
              - sekharan@us.ibm.com   |      .......you may get it.
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