Re: [1/3] Add __GFP_THISNODE to avoid fallback to other nodes and ignore cpuset/memory policy restrictions.

[Andrew Morton <akpm@osdl.org>]

On Fri, 11 Aug 2006 11:15:08 -0700 (PDT)
Christoph Lameter <clameter@sgi.com> wrote:

> On Fri, 11 Aug 2006, Andrew Morton wrote:
> 
> > > I would rather avoid fiddling around with making __GFP_xxx conditional.
> > > We have seen  to what problems this could lead.
> > 
> > What problems?
> 
> I just cleaned out the #ifdefs from the __GFP_xx section because you 
> told me that some comparisions could go haywire. if __GFP_xx would be zero. See 
> our discussion recently on __GFP_DMA32.
> 
> F.e. Tests like (__GFP_DMA | __GFP_THISNODE) == __GFP_THISNODE
> would give wrong positives if __GFP_THISNODE would be 0.

mutter.  No ifdefs, please.  We already have 41 #ifdef NUMA's in ./*/*.c

How about we do

/*
 * We do this to avoid lots of ifdefs and their consequential conditional
 * compilation
 */
#ifdef CONFIG_NUMA
#define NUMA_BUILD 1
#else
#define NUMA_BUILD 0
#endif

Then we can do

--- a/mm/page_alloc.c~a
+++ a/mm/page_alloc.c
@@ -903,7 +903,7 @@ get_page_from_freelist(gfp_t gfp_mask, u
 	 */
 	do {
 		zone = *z;
-		if (unlikely((gfp_mask & __GFP_THISNODE) &&
+		if (NUMA_BUILD && unlikely((gfp_mask & __GFP_THISNODE) &&
 			zone->zone_pgdat != zonelist->zones[0]->zone_pgdat))
 				break;
 		if ((alloc_flags & ALLOC_CPUSET) &&
_

in lots of places.

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