linux-kernel - Re: [PATCH 02/10] hugetlb: add allocate function for hugepage migration

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Date:	Wed, 22 Sep 2010 09:37:31 +0100
From:	Mel Gorman <mel@....ul.ie>
To:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Wu Fengguang <fengguang.wu@...el.com>,
	Jun'ichi Nomura <j-nomura@...jp.nec.com>,
	linux-mm <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 02/10] hugetlb: add allocate function for hugepage
	migration

On Wed, Sep 22, 2010 at 01:41:51PM +0900, Naoya Horiguchi wrote:
> Hi,
> 
> Thank you for your review.
> 
> On Mon, Sep 20, 2010 at 11:59:16AM +0100, Mel Gorman wrote:
> > On Wed, Sep 08, 2010 at 10:19:33AM +0900, Naoya Horiguchi wrote:
> ...
> > > @@ -770,11 +776,10 @@ static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
> > >  	return ret;
> > >  }
> > >  
> > > -static struct page *alloc_buddy_huge_page(struct hstate *h,
> > > -			struct vm_area_struct *vma, unsigned long address)
> > > +static struct page *alloc_buddy_huge_page(struct hstate *h, int nid)
> > >  {
> > >  	struct page *page;
> > > -	unsigned int nid;
> > > +	unsigned int r_nid;
> > >  
> > 
> > Why the rename, just to avoid changing the value of a function parameter?
> 
> I think it's better that a simple name is given to function parameter
> than to internal variable, because the former is paid more attention
> from other developers than the latter is.
> 

Ok.

> > >  	if (h->order >= MAX_ORDER)
> > >  		return NULL;
> > > @@ -812,9 +817,14 @@ static struct page *alloc_buddy_huge_page(struct hstate *h,
> > >  	}
> > >  	spin_unlock(&hugetlb_lock);
> > >  
> > > -	page = alloc_pages(htlb_alloc_mask|__GFP_COMP|
> > > -					__GFP_REPEAT|__GFP_NOWARN,
> > > -					huge_page_order(h));
> > > +	if (nid == NUMA_NO_NODE)
> > > +		page = alloc_pages(htlb_alloc_mask|__GFP_COMP|
> > > +				   __GFP_REPEAT|__GFP_NOWARN,
> > > +				   huge_page_order(h));
> > > +	else
> > > +		page = alloc_pages_exact_node(nid,
> > > +			htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
> > > +			__GFP_REPEAT|__GFP_NOWARN, huge_page_order(h));
> > >  
> > 
> > Why not just call alloc_pages_node()?
> 
> Ah, we can bring together these two allocate functions.
> I'll do it.
> 
> Here is a revised patch.
> 
> Thanks,
> Naoya Horiguchi
> ---
> Date: Wed, 22 Sep 2010 13:18:54 +0900
> Subject: [PATCH 02/10] hugetlb: add allocate function for hugepage migration
> 
> We can't use existing hugepage allocation functions to allocate hugepage
> for page migration, because page migration can happen asynchronously with
> the running processes and page migration users should call the allocation
> function with physical addresses (not virtual addresses) as arguments.
> 
> ChangeLog since v3:
> - unify alloc_buddy_huge_page() and alloc_buddy_huge_page_node()
> - bring together branched allocate functions
> 
> ChangeLog since v2:
> - remove unnecessary get/put_mems_allowed() (thanks to David Rientjes)
> 
> ChangeLog since v1:
> - add comment on top of alloc_huge_page_no_vma()
> 
> Signed-off-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
> Signed-off-by: Jun'ichi Nomura <j-nomura@...jp.nec.com>

Acked-by: Mel Gorman <mel@....ul.ie>

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab
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