linux-kernel - Re: [S+Q3 03/23] slub: Use a constant for a unspecified node.

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Message-ID: <alpine.DEB.2.00.1008040946200.11084@router.home>
Date:	Wed, 4 Aug 2010 11:15:29 -0500 (CDT)
From:	Christoph Lameter <cl@...ux-foundation.org>
To:	David Rientjes <rientjes@...gle.com>
cc:	Pekka Enberg <penberg@...helsinki.fi>, linux-mm@...ck.org,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	linux-kernel@...r.kernel.org, Nick Piggin <npiggin@...e.de>
Subject: Re: [S+Q3 03/23] slub: Use a constant for a unspecified node.

On Tue, 3 Aug 2010, David Rientjes wrote:

> >  static struct page *get_partial(struct kmem_cache *s, gfp_t flags, int node)
> >  {
> >  	struct page *page;
> > -	int searchnode = (node == -1) ? numa_node_id() : node;
> > +	int searchnode = (node == NUMA_NO_NODE) ? numa_node_id() : node;
> >
> >  	page = get_partial_node(get_node(s, searchnode));
> >  	if (page || (flags & __GFP_THISNODE) || node != -1)
>
> This has a merge conflict with 2.6.35 since it has this:
>
> 	page = get_partial_node(get_node(s, searchnode));
> 	if (page || (flags & __GFP_THISNODE))
> 		return page;
>
> 	return get_any_partial(s, flags);
>
> so what happened to the dropped check for returning get_any_partial() when
> node != -1?  I added the check for benchmarking.

Strange no merge conflict here. Are you sure you use upstream?

GFP_THISNODE does not matter too much. If page == NULL then we failed
to allocate a page on a specific node and have to either give up (and then
extend the slab) or take a page from another node.

We always have give up to go to the page allocator if GFP_THIS_NODE was
set. The modification to additionally also go to the page allocator if
a node was just set even without GFP_THISNODE. So checking for
GFP_THISNODE does not make sense anymore.




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