Re: [RFC] memory unplug v5 [4/6] page isolation

[Dave Hansen <hansendc@us.ibm.com>]

On Thu, 2007-06-14 at 16:03 +0900, KAMEZAWA Hiroyuki wrote:
> +#ifdef CONFIG_HOLES_IN_ZONE
> +static inline struct page *
> +__first_valid_page(unsigned long pfn, unsigned long nr_page)
> +{
> +	int i;
> +	struct page *page;
> +	for (i = 0; i < nr_page; i++)
> +		if (pfn_valid_within(pfn + i))
> +			break;
> +	if (unlikely(i == nr_pages))
> +		return NULL;
> +	return pfn_to_page(pfn + i);
> +}
> +#else
> +static inline struct page *
> +__first_valid_page(unsigned long pfn, unsigned long nr_page)
> +{
> +	return pfn_to_page(pfn);
> +}
> +#endif

I think this entire #ifdef is unneeded.  pfn_valid_within() will be
#defined to 1 if CONFIG_HOLES_IN_ZONE=n, so that function will come out
looking like this:

+__first_valid_page(unsigned long pfn, unsigned long nr_page)
> +{
> +	int i;
> +	struct page *page;
> +	for (i = 0; i < nr_page; i++)
> +		if (1)
> +			break;
> +	if (unlikely(i == nr_pages))
> +		return NULL;
> +	return pfn_to_page(pfn + i);
> +}

I think the compiler can optimize that. :)

-- Dave

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