Re: [RFC] memory unplug v5 [5/6] page unplug

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Fri, 15 Jun 2007 08:52:41 -0700
Dave Hansen <hansendc@us.ibm.com> wrote:

> On Thu, 2007-06-14 at 16:04 +0900, KAMEZAWA Hiroyuki wrote:
> > 
> > +       if (start_pfn & (pageblock_nr_pages - 1))
> > +               return -EINVAL;
> > +       if (end_pfn & (pageblock_nr_pages - 1))
> > +               return -EINVAL; 
> 
> After reading these, I'm still not sure I know what a pageblock is
> supposed to be. :)  Did those come from Mel's patches?
> 
yes.

> In any case, I think it might be helpful to wrap up some of those
> references in functions.  I was always looking at the patches trying to
> find if "pageblock_nr_pages" was a local variable or not.  A function
> would surely tell me.
> 
> static inline int pfn_is_pageblock_aligned(unsigned long pfn)
> {
> 	return pfn & (pageblock_nr_pages - 1)
> }
> 
> and, then you get
> 
> 		BUG_ON(!pfn_is_pageblock_aligned(start_pfn));
> 
> It's pretty obvious what is going on, there. 
> 
Hmm...I'll try that in the next version. But Is there some macro
to do this ? like..
--
#define IS_ALIGNED(val, align)	((val) & (align - 1))
--

-Kame

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