Re: [PATCH] mm: Do not stall in synchronous compaction for THPallocations

[Andrea Arcangeli]

On Thu, Nov 10, 2011 at 10:06:16AM +0000, Mel Gorman wrote:
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 963c5de..cddc2d0 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -2213,7 +2213,13 @@ rebalance:
>  					sync_migration);
>  	if (page)
>  		goto got_pg;
> -	sync_migration = true;
> +
> +	/*
> +	 * Do not use sync migration for transparent hugepage allocations as
> +	 * it could stall writing back pages which is far worse than simply
> +	 * failing to promote a page.
> +	 */
> +	sync_migration = !(gfp_mask & __GFP_NO_KSWAPD);
>  
>  	/* Try direct reclaim and then allocating */
>  	page = __alloc_pages_direct_reclaim(gfp_mask, order,

Reviewed-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
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