Re: [PATCH 31/35] Optimistically check the first page on the PCPfree list is suitable

[Christoph Lameter]

On Mon, 16 Mar 2009, Mel Gorman wrote:

> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index bb5bd5e..8568284 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1212,6 +1212,12 @@ again:
>  				if (pcp_page_suit(page, order))
>  					break;
>  		} else {
> +			/* Optimistic before we start a list search */
> +			page = list_entry(list->next, struct page, lru);
> +			if (pcp_page_suit(page, order))
> +				goto found;
> +
> +			/* Do the search */
>  			list_for_each_entry(page, list, lru)
>  				if (pcp_page_suit(page, order))
>  					break;

I am not convinced that this is beneficial. If it would then the compiler
would unroll the loop.


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