Re: [RFC] Replace the watermark-related union in struct zone witha watermark[] array

[David Rientjes]

On Mon, 27 Apr 2009, Mel Gorman wrote:

> > I thought the suggestion was for something like
> > 
> > 	#define zone_wmark_min(z)	(z->pages_mark[WMARK_MIN])
> > 	...
> 
> Was it the only suggestion? I thought just replacing the union with an
> array would be an option as well.
> 
> The #define approach also requires setter versions like
> 
> static inline set_zone_wmark_min(struct zone *z, unsigned long val)
> {
> 	z->pages_mark[WMARK_MIN] = val;
> }
> 
> and you need one of those for each watermark if you are to avoid weirdness like
> 
> zone_wmark_min(z) = val;
> 
> which looks all wrong.

Agreed, but we only set watermarks in a couple of different locations and 
they really have no reason to change otherwise, so I don't think it's 
necessary to care too much about how the setter looks.

Adding individual get/set functions for each watermark seems like 
overkill.

I personally had no problem with the union struct aliasing the array, I 
think ->pages_min, ->pages_low, etc. are already very familiar.
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