From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mike Snitzer <snitzer@redhat.com>
Subject: Re: The DM_BUFIO_HASH_BITS is defined as 20, any plan to make it
 flexible?
Date: Tue, 2 Dec 2014 09:00:17 -0500
Message-ID: <20141202140015.GB5985@redhat.com>
References: <547D7BC6.6070708@windriver.com>
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To: zhangxiao <xiao.zhang@windriver.com>
Cc: agk@redhat.com, linux-kernel@vger.kernel.org, NeilBrown <neilb@suse.de>, linux-raid@vger.kernel.org, dm-devel@redhat.com
List-Id: linux-raid.ids

On Tue, Dec 02 2014 at  3:43am -0500,
zhangxiao <xiao.zhang@windriver.com> wrote:

> Hi Experts,
> 
> See drivers/md/dm-bufio.c as below:
>   50 /*
>   51  * Buffer hash
>   52  */
>   53 #define DM_BUFIO_HASH_BITS      20
>   54 #define DM_BUFIO_HASH(block) \
>   55         ((((block) >> DM_BUFIO_HASH_BITS) ^ (block)) & \
>   56          ((1 << DM_BUFIO_HASH_BITS) - 1))
> "drivers/md/dm-bufio.c" 1854L, 45375C
> 
> DM_BUFIO_HASH_BITS was defined as 20 and it maybe not fit for some
> use case with limited resources. Do we have any plan to make it more
> flexible? Like module parameter or something else?

No immediate plans.