LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Minchan Kim <minchan.kim@gmail.com>
To: KyongHo Cho <pullip.cho@samsung.com>
Cc: linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, linux-samsung-soc@vger.kernel.org,
	Kukjin Kim <kgene.kim@samsung.com>,
	Ilho Lee <ilho215.lee@samsung.com>,
	KeyYoung Park <keyyoung.park@samsung.com>
Subject: Re: [PATCH] ARM: mm: Regarding section when dealing with meminfo
Date: Thu, 20 Jan 2011 23:28:44 +0900	[thread overview]
Message-ID: <20110120142844.GA28358@barrios-desktop> (raw)
In-Reply-To: <1295516739-9839-1-git-send-email-pullip.cho@samsung.com>

On Thu, Jan 20, 2011 at 06:45:39PM +0900, KyongHo Cho wrote:
> Sparsemem allows that a bank of memory spans over several adjacent
> sections if the start address and the end address of the bank
> belong to different sections.
> When gathering statictics of physical memory in mem_init() and
> show_mem(), this possiblity was not considered.

Please write down the result if we doesn't consider this patch.
I can understand what happens but for making good description and review,
merging easily, it would be better to write down the result without 
the patch explicitly.

> 
> This patch guarantees that simple increasing the pointer to page
> descriptors does not exceed the boundary of a section.
> 
> Signed-off-by: KyongHo Cho <pullip.cho@samsung.com>
> ---
>  arch/arm/mm/init.c |   74 +++++++++++++++++++++++++++++++++++----------------
>  1 files changed, 51 insertions(+), 23 deletions(-)
> 
> diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> index 57c4c5c..6ccecbe 100644
> --- a/arch/arm/mm/init.c
> +++ b/arch/arm/mm/init.c
> @@ -93,24 +93,38 @@ void show_mem(void)
>  
>  		pfn1 = bank_pfn_start(bank);
>  		pfn2 = bank_pfn_end(bank);
> -
> +#ifndef CONFIG_SPARSEMEM
>  		page = pfn_to_page(pfn1);
>  		end  = pfn_to_page(pfn2 - 1) + 1;
> -
> +#else
> +		pfn2--;
>  		do {
> -			total++;
> -			if (PageReserved(page))
> -				reserved++;
> -			else if (PageSwapCache(page))
> -				cached++;
> -			else if (PageSlab(page))
> -				slab++;
> -			else if (!page_count(page))
> -				free++;
> -			else
> -				shared += page_count(page) - 1;
> -			page++;
> -		} while (page < end);
> +			page = pfn_to_page(pfn1);
> +			if (pfn_to_section_nr(pfn1) < pfn_to_section_nr(pfn2)) {
> +				pfn1 += PAGES_PER_SECTION;
> +				pfn1 &= PAGE_SECTION_MASK;
> +			} else {
> +				pfn1 = pfn2;
> +			}
> +			end = pfn_to_page(pfn1) + 1;
> +#endif
> +			do {
> +				total++;
> +				if (PageReserved(page))
> +					reserved++;
> +				else if (PageSwapCache(page))
> +					cached++;
> +				else if (PageSlab(page))
> +					slab++;
> +				else if (!page_count(page))
> +					free++;
> +				else
> +					shared += page_count(page) - 1;
> +				page++;
> +			} while (page < end);
> +#ifdef CONFIG_SPARSEMEM
> +		} while (pfn1 < pfn2);
> +#endif
>  	}
>  
>  	printk("%d pages of RAM\n", total);
> @@ -470,17 +484,31 @@ void __init mem_init(void)
>  
>  		pfn1 = bank_pfn_start(bank);
>  		pfn2 = bank_pfn_end(bank);
> -
> +#ifndef CONFIG_SPARSEMEM
>  		page = pfn_to_page(pfn1);
>  		end  = pfn_to_page(pfn2 - 1) + 1;
> -
> +#else
> +		pfn2--;
>  		do {
> -			if (PageReserved(page))
> -				reserved_pages++;
> -			else if (!page_count(page))
> -				free_pages++;
> -			page++;
> -		} while (page < end);
> +			page = pfn_to_page(pfn1);
> +			if (pfn_to_section_nr(pfn1) < pfn_to_section_nr(pfn2)) {
> +				pfn1 += PAGES_PER_SECTION;
> +				pfn1 &= PAGE_SECTION_MASK;
> +			} else {
> +				pfn1 = pfn2;
> +			}
> +			end = pfn_to_page(pfn1) + 1;
> +#endif
> +			do {
> +				if (PageReserved(page))
> +					reserved_pages++;
> +				else if (!page_count(page))
> +					free_pages++;
> +				page++;
> +			} while (page < end);
> +#ifdef CONFIG_SPARSEMEM
> +		} while (pfn1 < pfn2);
> +#endif
>  	}

Hmm.. new ifndef magic makes code readability bad.
Couldn't we do it by simple pfn iterator not page and pfn_valid check?

>  
>  	/*
> -- 
> 1.6.2.5
> 
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

-- 
Kind regards,
Minchan Kim

  reply	other threads:[~2011-01-20 14:28 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-01-20  9:45 KyongHo Cho
2011-01-20 14:28 ` Minchan Kim [this message]
2011-01-20 17:25   ` Dave Hansen
     [not found]   ` <AANLkTinXAiShaf1f69ufVHg7KPaY5j=jmOTtK71GNNp5@mail.gmail.com>
2011-01-20 17:43     ` Minchan Kim
2011-01-20 17:44       ` Minchan Kim
2011-01-20 17:52         ` KyongHo Cho
2011-01-20 17:20 ` Dave Hansen
     [not found]   ` <AANLkTi=nsAOtLPK75Wy5Rm8pfWob8xTP5259DyYuxR9J@mail.gmail.com>
2011-01-20 17:48     ` KyongHo Cho
2011-01-20 18:04     ` Dave Hansen
2011-01-20 18:01   ` Russell King - ARM Linux
2011-01-20 18:11     ` Dave Hansen
2011-01-23 18:05       ` Russell King - ARM Linux
2011-01-24 16:52         ` Dave Hansen
2011-01-24 17:58           ` Russell King - ARM Linux
2011-01-24 18:47             ` Dave Hansen
2011-01-25  0:33             ` KyongHo Cho
2011-01-21  2:12     ` KyongHo Cho
2011-01-21 10:38       ` Russell King - ARM Linux
2011-01-21 11:15         ` KyongHo Cho

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20110120142844.GA28358@barrios-desktop \
    --to=minchan.kim@gmail.com \
    --cc=ilho215.lee@samsung.com \
    --cc=keyyoung.park@samsung.com \
    --cc=kgene.kim@samsung.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux-samsung-soc@vger.kernel.org \
    --cc=pullip.cho@samsung.com \
    --subject='Re: [PATCH] ARM: mm: Regarding section when dealing with meminfo' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).