linux-kernel - Re: [PATCH] mm/zsmalloc: avoid duplicate assignment of prev

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Date:	Fri, 21 Nov 2014 12:43:55 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Mahendran Ganesh <opensource.ganesh@...il.com>
Cc:	ngupta@...are.org, iamjoonsoo.kim@....com, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/zsmalloc: avoid duplicate assignment of prev_class

On Thu, Nov 20, 2014 at 09:08:33PM +0800, Mahendran Ganesh wrote:
> In zs_create_pool(), prev_class is assigned (ZS_SIZE_CLASSES - 1)
> times. And the prev_class only references to the previous alloc
> size_class. So we do not need unnecessary assignement.
> 
> This patch modifies *prev_class* to *prev_alloc_class*. And the
> *prev_alloc_class* will only be assigned when a new size_class
> structure is allocated.
> 
> Signed-off-by: Mahendran Ganesh <opensource.ganesh@...il.com>
> ---
>  mm/zsmalloc.c |    9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index b3b57ef..ac2b396 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -970,7 +970,7 @@ struct zs_pool *zs_create_pool(gfp_t flags)
>  		int size;
>  		int pages_per_zspage;
>  		struct size_class *class;
> -		struct size_class *prev_class;
> +		struct size_class *uninitialized_var(prev_alloc_class);

https://lkml.org/lkml/2012/10/27/71
In addition, I prefer prev_class.

Thanks.

-- 
Kind regards,
Minchan Kim
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