Re: [PATCH] hugetlb: restore interleaving of bootmem huge pages

[Mel Gorman <mel@csn.ul.ie>]

On Thu, Jul 16, 2009 at 10:31:02AM -0400, Lee Schermerhorn wrote:
> PATCH restore interleaving of bootmem huge pages
> 
> Against: 2.6.31-rc1-mmotm-090625-1549
> atop the "hugetlb-balance-freeing-of-huge-pages-across-node" series
> 
> I noticed that alloc_bootmem_huge_page() will only advance to the
> next node on failure to allocate a huge page, potentially filling 
> nodes with huge-pages.  I asked about this on linux-mm and linux-numa,
> cc'ing the usual huge page suspects.
> 
> Mel Gorman responded:
> 
> 	I strongly suspect that the same node being used until allocation
> 	failure instead of round-robin is an oversight and not deliberate
> 	at all. It appears to be a side-effect of a fix made way back in
> 	commit 63b4613c3f0d4b724ba259dc6c201bb68b884e1a ["hugetlb: fix
> 	hugepage allocation with memoryless nodes"]. Prior to that patch
> 	it looked like allocations would always round-robin even when
> 	allocation was successful.
> 
> This patch--factored out of my "hugetlb mempolicy" series--moves the
> advance of the hstate next node from which to allocate up before the
> test for success of the attempted allocation.
> 
> Note that alloc_bootmem_huge_page() is only used for order > MAX_ORDER
> huge pages.
> 
> I'll post a separate patch for mainline/stable, as the above mentioned
> "balance freeing" series renamed the next node to alloc function.
> 
> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>

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

> 
>  mm/hugetlb.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> Index: linux-2.6.31-rc1-mmotm-090625-1549/mm/hugetlb.c
> ===================================================================
> --- linux-2.6.31-rc1-mmotm-090625-1549.orig/mm/hugetlb.c	2009-07-13 09:05:22.000000000 -0400
> +++ linux-2.6.31-rc1-mmotm-090625-1549/mm/hugetlb.c	2009-07-13 09:06:22.000000000 -0400
> @@ -1030,6 +1030,7 @@ int __weak alloc_bootmem_huge_page(struc
>  				NODE_DATA(h->next_nid_to_alloc),
>  				huge_page_size(h), huge_page_size(h), 0);
>  
> +		hstate_next_node_to_alloc(h);
>  		if (addr) {
>  			/*
>  			 * Use the beginning of the huge page to store the
> @@ -1039,7 +1040,6 @@ int __weak alloc_bootmem_huge_page(struc
>  			m = addr;
>  			goto found;
>  		}
> -		hstate_next_node_to_alloc(h);
>  		nr_nodes--;
>  	}
>  	return 0;
> 
> 

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