Re: linearly index zone->node_zonelists[]

[Christoph Lameter <clameter@sgi.com>]

On Tue, 8 Aug 2006, Andy Whitcroft wrote:

> The GFP_foo flags are modifiers specifying some property we require from an
> allocation.  Currently all modifiers are singletons, that is they are all
> specified in isolation.  However, the code base as it stands does not enforce
> this.  I could see use cases where we might want to specify more than one
> flag.  For example a GFP_NODE_LOCAL flags which could be specified with any of
> the 'zone selectors'.  This would naturally work with the current
> implementation.

I have a patch here that implements such a thing its called 
__GFP_THISNODE but it does not use any of the bit mask features that I 
removed. __GFP_THISNODE simply checks if the allocation zone is local.

> Making the change you suggest here codifies the singleton status of these
> bits.  We should be sure we are not going to use this feature before its
> removed.  I am not sure I am comfortable saying there are no uses for it.

This certainly codifies the singleton status. However, I cannot imagine 
any uses for it that would not also require other significant changes in 
the page allocator. We can revisit that if someone comes up with a feature 
that needs this.

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