Re: [PATCH 1/2] hugetlb reservations: move region tracking earlier

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

On (23/06/08 18:35), Andy Whitcroft didst pronounce:
> Move the region tracking code much earlier so we can use it for page
> presence tracking later on.  No code is changed, just its location.
> 
> Signed-off-by: Andy Whitcroft <apw@shadowen.org>

Straight-forward code-move.

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

> ---
>  mm/hugetlb.c |  246 +++++++++++++++++++++++++++++----------------------------
>  1 files changed, 125 insertions(+), 121 deletions(-)
> 
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 0f76ed1..d701e39 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -47,6 +47,131 @@ static unsigned long __initdata default_hstate_size;
>  static DEFINE_SPINLOCK(hugetlb_lock);
>  
>  /*
> + * Region tracking -- allows tracking of reservations and instantiated pages
> + *                    across the pages in a mapping.
> + */
> +struct file_region {
> +	struct list_head link;
> +	long from;
> +	long to;
> +};
> +
> +static long region_add(struct list_head *head, long f, long t)
> +{
> +	struct file_region *rg, *nrg, *trg;
> +
> +	/* Locate the region we are either in or before. */
> +	list_for_each_entry(rg, head, link)
> +		if (f <= rg->to)
> +			break;
> +
> +	/* Round our left edge to the current segment if it encloses us. */
> +	if (f > rg->from)
> +		f = rg->from;
> +
> +	/* Check for and consume any regions we now overlap with. */
> +	nrg = rg;
> +	list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
> +		if (&rg->link == head)
> +			break;
> +		if (rg->from > t)
> +			break;
> +
> +		/* If this area reaches higher then extend our area to
> +		 * include it completely.  If this is not the first area
> +		 * which we intend to reuse, free it. */
> +		if (rg->to > t)
> +			t = rg->to;
> +		if (rg != nrg) {
> +			list_del(&rg->link);
> +			kfree(rg);
> +		}
> +	}
> +	nrg->from = f;
> +	nrg->to = t;
> +	return 0;
> +}
> +
> +static long region_chg(struct list_head *head, long f, long t)
> +{
> +	struct file_region *rg, *nrg;
> +	long chg = 0;
> +
> +	/* Locate the region we are before or in. */
> +	list_for_each_entry(rg, head, link)
> +		if (f <= rg->to)
> +			break;
> +
> +	/* If we are below the current region then a new region is required.
> +	 * Subtle, allocate a new region at the position but make it zero
> +	 * size such that we can guarantee to record the reservation. */
> +	if (&rg->link == head || t < rg->from) {
> +		nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
> +		if (!nrg)
> +			return -ENOMEM;
> +		nrg->from = f;
> +		nrg->to   = f;
> +		INIT_LIST_HEAD(&nrg->link);
> +		list_add(&nrg->link, rg->link.prev);
> +
> +		return t - f;
> +	}
> +
> +	/* Round our left edge to the current segment if it encloses us. */
> +	if (f > rg->from)
> +		f = rg->from;
> +	chg = t - f;
> +
> +	/* Check for and consume any regions we now overlap with. */
> +	list_for_each_entry(rg, rg->link.prev, link) {
> +		if (&rg->link == head)
> +			break;
> +		if (rg->from > t)
> +			return chg;
> +
> +		/* We overlap with this area, if it extends futher than
> +		 * us then we must extend ourselves.  Account for its
> +		 * existing reservation. */
> +		if (rg->to > t) {
> +			chg += rg->to - t;
> +			t = rg->to;
> +		}
> +		chg -= rg->to - rg->from;
> +	}
> +	return chg;
> +}
> +
> +static long region_truncate(struct list_head *head, long end)
> +{
> +	struct file_region *rg, *trg;
> +	long chg = 0;
> +
> +	/* Locate the region we are either in or before. */
> +	list_for_each_entry(rg, head, link)
> +		if (end <= rg->to)
> +			break;
> +	if (&rg->link == head)
> +		return 0;
> +
> +	/* If we are in the middle of a region then adjust it. */
> +	if (end > rg->from) {
> +		chg = rg->to - end;
> +		rg->to = end;
> +		rg = list_entry(rg->link.next, typeof(*rg), link);
> +	}
> +
> +	/* Drop any remaining regions. */
> +	list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
> +		if (&rg->link == head)
> +			break;
> +		chg += rg->to - rg->from;
> +		list_del(&rg->link);
> +		kfree(rg);
> +	}
> +	return chg;
> +}
> +
> +/*
>   * Convert the address within this vma to the page offset within
>   * the mapping, in base page units.
>   */
> @@ -649,127 +774,6 @@ static void return_unused_surplus_pages(struct hstate *h,
>  	}
>  }
>  
> -struct file_region {
> -	struct list_head link;
> -	long from;
> -	long to;
> -};
> -
> -static long region_add(struct list_head *head, long f, long t)
> -{
> -	struct file_region *rg, *nrg, *trg;
> -
> -	/* Locate the region we are either in or before. */
> -	list_for_each_entry(rg, head, link)
> -		if (f <= rg->to)
> -			break;
> -
> -	/* Round our left edge to the current segment if it encloses us. */
> -	if (f > rg->from)
> -		f = rg->from;
> -
> -	/* Check for and consume any regions we now overlap with. */
> -	nrg = rg;
> -	list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
> -		if (&rg->link == head)
> -			break;
> -		if (rg->from > t)
> -			break;
> -
> -		/* If this area reaches higher then extend our area to
> -		 * include it completely.  If this is not the first area
> -		 * which we intend to reuse, free it. */
> -		if (rg->to > t)
> -			t = rg->to;
> -		if (rg != nrg) {
> -			list_del(&rg->link);
> -			kfree(rg);
> -		}
> -	}
> -	nrg->from = f;
> -	nrg->to = t;
> -	return 0;
> -}
> -
> -static long region_chg(struct list_head *head, long f, long t)
> -{
> -	struct file_region *rg, *nrg;
> -	long chg = 0;
> -
> -	/* Locate the region we are before or in. */
> -	list_for_each_entry(rg, head, link)
> -		if (f <= rg->to)
> -			break;
> -
> -	/* If we are below the current region then a new region is required.
> -	 * Subtle, allocate a new region at the position but make it zero
> -	 * size such that we can guarantee to record the reservation. */
> -	if (&rg->link == head || t < rg->from) {
> -		nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
> -		if (!nrg)
> -			return -ENOMEM;
> -		nrg->from = f;
> -		nrg->to   = f;
> -		INIT_LIST_HEAD(&nrg->link);
> -		list_add(&nrg->link, rg->link.prev);
> -
> -		return t - f;
> -	}
> -
> -	/* Round our left edge to the current segment if it encloses us. */
> -	if (f > rg->from)
> -		f = rg->from;
> -	chg = t - f;
> -
> -	/* Check for and consume any regions we now overlap with. */
> -	list_for_each_entry(rg, rg->link.prev, link) {
> -		if (&rg->link == head)
> -			break;
> -		if (rg->from > t)
> -			return chg;
> -
> -		/* We overlap with this area, if it extends futher than
> -		 * us then we must extend ourselves.  Account for its
> -		 * existing reservation. */
> -		if (rg->to > t) {
> -			chg += rg->to - t;
> -			t = rg->to;
> -		}
> -		chg -= rg->to - rg->from;
> -	}
> -	return chg;
> -}
> -
> -static long region_truncate(struct list_head *head, long end)
> -{
> -	struct file_region *rg, *trg;
> -	long chg = 0;
> -
> -	/* Locate the region we are either in or before. */
> -	list_for_each_entry(rg, head, link)
> -		if (end <= rg->to)
> -			break;
> -	if (&rg->link == head)
> -		return 0;
> -
> -	/* If we are in the middle of a region then adjust it. */
> -	if (end > rg->from) {
> -		chg = rg->to - end;
> -		rg->to = end;
> -		rg = list_entry(rg->link.next, typeof(*rg), link);
> -	}
> -
> -	/* Drop any remaining regions. */
> -	list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
> -		if (&rg->link == head)
> -			break;
> -		chg += rg->to - rg->from;
> -		list_del(&rg->link);
> -		kfree(rg);
> -	}
> -	return chg;
> -}
> -
>  /*
>   * Determine if the huge page at addr within the vma has an associated
>   * reservation.  Where it does not we will need to logically increase
> -- 
> 1.5.6.205.g7ca3a
> 

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

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