linux-kernel - Re: [PATCH v3 3/5] handle zcache_[eph|pers]

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Date:	Sat, 16 Mar 2013 09:11:06 -0400
From:	Konrad Rzeszutek Wilk <konrad@...nok.org>
To:	Wanpeng Li <liwanp@...ux.vnet.ibm.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dan Magenheimer <dan.magenheimer@...cle.com>,
	Seth Jennings <sjenning@...ux.vnet.ibm.com>,
	Minchan Kim <minchan@...nel.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/5] handle zcache_[eph|pers]_zpages for zero-filled
 page

On Fri, Mar 15, 2013 at 10:34:18AM +0800, Wanpeng Li wrote:
> Increment/decrement zcache_[eph|pers]_zpages for zero-filled pages,
> the main point of the counters for zpages and pageframes is to be 
> able to calculate density == zpages/pageframes. A zero-filled page 
> becomes a zpage that "compresses" to zero bytes and, as a result, 
> requires zero pageframes for storage. So the zpages counter should 
> be increased but the pageframes counter should not.
> 
> [Dan Magenheimer <dan.magenheimer@...cle.com>: patch description]
> Acked-by: Dan Magenheimer <dan.magenheimer@...cle.com>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> Signed-off-by: Wanpeng Li <liwanp@...ux.vnet.ibm.com>
> ---
>  drivers/staging/zcache/zcache-main.c |    7 ++++++-
>  1 files changed, 6 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c
> index 6c35c7d..ef8c960 100644
> --- a/drivers/staging/zcache/zcache-main.c
> +++ b/drivers/staging/zcache/zcache-main.c
> @@ -863,6 +863,8 @@ static int zcache_pampd_get_data_and_free(char *data, size_t *sizep, bool raw,
>  	if (pampd == (void *)ZERO_FILLED) {
>  		handle_zero_filled_page(data);
>  		zero_filled = true;
> +		zsize = 0;
> +		zpages = 1;
>  		if (!raw)
>  			*sizep = PAGE_SIZE;
>  		goto zero_fill;
> @@ -917,8 +919,11 @@ static void zcache_pampd_free(void *pampd, struct tmem_pool *pool,
>  
>  	BUG_ON(preemptible());
>  
> -	if (pampd == (void *)ZERO_FILLED)
> +	if (pampd == (void *)ZERO_FILLED) {
>  		zero_filled = true;
> +		zsize = 0;
> +		zpages = 1;
> +	}
>  
>  	if (pampd_is_remote(pampd) && !zero_filled) {
>  
> -- 
> 1.7.7.6
> 
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