linux-kernel - Re: [PATCH 2/4] mm: cma: add functions to get region pages counters

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Date:	Fri, 13 Feb 2015 12:11:50 +0900
From:	Joonsoo Kim <iamjoonsoo.kim@....com>
To:	Stefan Strogin <s.strogin@...tner.samsung.com>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Dmitry Safonov <d.safonov@...tner.samsung.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Michal Nazarewicz <mina86@...a86.com>,
	aneesh.kumar@...ux.vnet.ibm.com,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Pintu Kumar <pintu.k@...sung.com>,
	Weijie Yang <weijie.yang@...sung.com>,
	Laura Abbott <lauraa@...eaurora.org>,
	SeongJae Park <sj38.park@...il.com>,
	Hui Zhu <zhuhui@...omi.com>, Minchan Kim <minchan@...nel.org>,
	Dyasly Sergey <s.dyasly@...sung.com>,
	Vyacheslav Tyrtov <v.tyrtov@...sung.com>,
	gregory.0xf0@...il.com, sasha.levin@...cle.com, gioh.kim@....com,
	pavel@....cz, stefan.strogin@...il.com
Subject: Re: [PATCH 2/4] mm: cma: add functions to get region pages counters

On Fri, Feb 13, 2015 at 01:15:42AM +0300, Stefan Strogin wrote:
> From: Dmitry Safonov <d.safonov@...tner.samsung.com>
> 
> Here are two functions that provide interface to compute/get used size
> and size of biggest free chunk in cma region.
> Add that information to debugfs.
> 
> Signed-off-by: Dmitry Safonov <d.safonov@...tner.samsung.com>
> Signed-off-by: Stefan Strogin <s.strogin@...tner.samsung.com>
> ---
>  include/linux/cma.h |  2 ++
>  mm/cma.c            | 30 ++++++++++++++++++++++++++++++
>  mm/cma_debug.c      | 24 ++++++++++++++++++++++++
>  3 files changed, 56 insertions(+)
> 
> diff --git a/include/linux/cma.h b/include/linux/cma.h
> index 4c2c83c..54a2c4d 100644
> --- a/include/linux/cma.h
> +++ b/include/linux/cma.h
> @@ -18,6 +18,8 @@ struct cma;
>  extern unsigned long totalcma_pages;
>  extern phys_addr_t cma_get_base(struct cma *cma);
>  extern unsigned long cma_get_size(struct cma *cma);
> +extern unsigned long cma_get_used(struct cma *cma);
> +extern unsigned long cma_get_maxchunk(struct cma *cma);
>  
>  extern int __init cma_declare_contiguous(phys_addr_t base,
>  			phys_addr_t size, phys_addr_t limit,
> diff --git a/mm/cma.c b/mm/cma.c
> index ed269b0..95e8121 100644
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -54,6 +54,36 @@ unsigned long cma_get_size(struct cma *cma)
>  	return cma->count << PAGE_SHIFT;
>  }
>  
> +unsigned long cma_get_used(struct cma *cma)
> +{
> +	unsigned long ret = 0;
> +
> +	mutex_lock(&cma->lock);
> +	/* pages counter is smaller than sizeof(int) */
> +	ret = bitmap_weight(cma->bitmap, (int)cma->count);
> +	mutex_unlock(&cma->lock);
> +
> +	return ret;
> +}

Need to consider order_per_bit for returing number of page rather
than number of bits.

> +
> +unsigned long cma_get_maxchunk(struct cma *cma)
> +{
> +	unsigned long maxchunk = 0;
> +	unsigned long start, end = 0;
> +
> +	mutex_lock(&cma->lock);
> +	for (;;) {
> +		start = find_next_zero_bit(cma->bitmap, cma->count, end);
> +		if (start >= cma->count)
> +			break;
> +		end = find_next_bit(cma->bitmap, cma->count, start);
> +		maxchunk = max(end - start, maxchunk);
> +	}
> +	mutex_unlock(&cma->lock);
> +
> +	return maxchunk;
> +}
> +

Same here.

Thanks.

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