linux-kernel - Re: [RFC v2 4/5] Only set page reserved in the memblock region

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Date:	Sat, 3 Aug 2013 15:04:54 -0500
From:	Nathan Zimmer <nzimmer@....com>
To:	Nathan Zimmer <nzimmer@....com>
Cc:	hpa@...or.com, mingo@...nel.org, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, holt@....com, rob@...dley.net, travis@....com,
	daniel@...ascale-asia.com, akpm@...ux-foundation.org,
	gregkh@...uxfoundation.org, yinghai@...nel.org, mgorman@...e.de
Subject: Re: [RFC v2 4/5] Only set page reserved in the memblock region

On Fri, Aug 02, 2013 at 12:44:26PM -0500, Nathan Zimmer wrote:
> Currently we when we initialze each page struct is set as reserved upon
> initialization.  This changes to starting with the reserved bit clear and
> then only setting the bit in the reserved region.
> 
> I could restruture a bit to eliminate the perform hit.  But I wanted to make
> sure I am on track first.
> 
> Signed-off-by: Robin Holt <holt@....com>
> Signed-off-by: Nathan Zimmer <nzimmer@....com>
> To: "H. Peter Anvin" <hpa@...or.com>
> To: Ingo Molnar <mingo@...nel.org>
> Cc: Linux Kernel <linux-kernel@...r.kernel.org>
> Cc: Linux MM <linux-mm@...ck.org>
> Cc: Rob Landley <rob@...dley.net>
> Cc: Mike Travis <travis@....com>
> Cc: Daniel J Blueman <daniel@...ascale-asia.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Greg KH <gregkh@...uxfoundation.org>
> Cc: Yinghai Lu <yinghai@...nel.org>
> Cc: Mel Gorman <mgorman@...e.de>
> ---
>  include/linux/mm.h |  2 ++
>  mm/nobootmem.c     |  3 +++
>  mm/page_alloc.c    | 16 ++++++++++++----
>  3 files changed, 17 insertions(+), 4 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index e0c8528..b264a26 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1322,6 +1322,8 @@ static inline void adjust_managed_page_count(struct page *page, long count)
>  	totalram_pages += count;
>  }
>  
> +extern void reserve_bootmem_region(unsigned long start, unsigned long end);
> +
>  /* Free the reserved page into the buddy system, so it gets managed. */
>  static inline void __free_reserved_page(struct page *page)
>  {
> diff --git a/mm/nobootmem.c b/mm/nobootmem.c
> index 2159e68..0840af2 100644
> --- a/mm/nobootmem.c
> +++ b/mm/nobootmem.c
> @@ -117,6 +117,9 @@ static unsigned long __init free_low_memory_core_early(void)
>  	phys_addr_t start, end, size;
>  	u64 i;
>  
> +	for_each_reserved_mem_region(i, &start, &end)
> +		reserve_bootmem_region(start, end);
> +
>  	for_each_free_mem_range(i, MAX_NUMNODES, &start, &end, NULL)
>  		count += __free_memory_core(start, end);
>  
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index df3ec13..382223e 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -697,17 +697,18 @@ static void free_one_page(struct zone *zone, struct page *page, int order,
>  	spin_unlock(&zone->lock);
>  }
>  
> -static void __init_single_page(unsigned long pfn, unsigned long zone, int nid)
> +static void __init_single_page(unsigned long pfn, unsigned long zone,
> +			       int nid, int page_count)
>  {
>  	struct page *page = pfn_to_page(pfn);
>  	struct zone *z = &NODE_DATA(nid)->node_zones[zone];
>  
>  	set_page_links(page, zone, nid, pfn);
>  	mminit_verify_page_links(page, zone, nid, pfn);
> -	init_page_count(page);
>  	page_mapcount_reset(page);
>  	page_nid_reset_last(page);
> -	SetPageReserved(page);
> +	set_page_count(page, page_count);
> +	ClearPageReserved(page);
>  
>  	/*
>  	 * Mark the block movable so that blocks are reserved for
> @@ -736,6 +737,13 @@ static void __init_single_page(unsigned long pfn, unsigned long zone, int nid)
>  #endif
>  }
>  
> +void reserve_bootmem_region(unsigned long start, unsigned long end)
> +{
> +	for (; start < end; start++)
> +		if (pfn_valid(start))
> +			SetPageReserved(pfn_to_page(start));
> +}
> +
>  static bool free_pages_prepare(struct page *page, unsigned int order)
>  {
>  	int i;
> @@ -4010,7 +4018,7 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
>  			if (!early_pfn_in_nid(pfn, nid))
>  				continue;
>  		}
> -		__init_single_page(pfn, zone, nid);
> +		__init_single_page(pfn, zone, nid, 1);
>  	}
>  }
>  
> -- 
> 1.8.2.1
> 
Actually I believe reserve_bootmem_region is wrong.  I am passing in phys_adr_t and not pfns.

It should be: 
void reserve_bootmem_region(unsigned long start, unsigned long end)
{
        unsigned long start_pfn = PFN_DOWN(start);
        unsigned long end_pfn = PFN_UP(end);

        for (; start_pfn < end_pfn; start_pfn++)
                if (pfn_valid(start_pfn))
                        SetPageReserved(pfn_to_page(start_pfn));
}

That also brings the timings back in line with the previous patch set.

Nate
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