Re: [RFC 1/3] Framework for accurate node based statistics

[Christoph Lameter]

On Thu, 8 Dec 2005, Nick Piggin wrote:

> Christoph Lameter wrote:
> > On Wed, 7 Dec 2005, Nick Piggin wrote:
> > > Sorry, I think I meant: why don't you just use the "add all counters
> > > from all per-cpu of the node" in order to find the node-statistic?
> > which function is that?
> > 
> 
> I'm thinking of get_page_state_node... but that's not quite the same
> thing. I guess sum all per-CPU counters from all zones in the node,
> but that's going to be costly on big machines.

The per cpu counters count when a cpu did an allocation. They do not count 
on which node the allocation was done and are thereofre not useful to 
determine the memory use on one node.

> So I'm not sure, I guess I don't have any bright ideas... there is the
> batching approach used by current pagecache_acct - is something like
> that not sufficient either?

The framework provides a similar approach by keeping differential 
counters for each processor.

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