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From: Cesar Eduardo Barros <cesarb@cesarb.net>
To: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>,
	devel@linuxdriverproject.org, linux-kernel@vger.kernel.org,
	gregkh@linuxfoundation.org, linux-mm@kvack.org,
	ngupta@vflare.org, konrad.wilk@oracle.com, minchan@kernel.org,
	fschmaus@gmail.com, andor.daam@googlemail.com,
	ilendir@googlemail.com, akpm@linux-foundation.org,
	mgorman@suse.de
Subject: Re: [PATCH 2/5] mm: frontswap: lazy initialization to allow tmem backends to build/run as modules
Date: Wed, 31 Oct 2012 19:42:53 -0200	[thread overview]
Message-ID: <50919B5D.9000100@cesarb.net> (raw)
In-Reply-To: <50915A5C.8000303@linux.vnet.ibm.com>

Em 31-10-2012 15:05, Seth Jennings escreveu:
> On 10/31/2012 10:07 AM, Dan Magenheimer wrote:
>> +#define MAX_INITIALIZABLE_SD 32
>
> MAX_INITIALIZABLE_SD should just be MAX_SWAPFILES
>
>> +static int sds[MAX_INITIALIZABLE_SD];
>
> Rather than store and array of enabled types indexed by type, why not
> an array of booleans indexed by type.  Or a bitfield if you really
> want to save space.

Since it is indexed by swap_info_struct's type, and frontswap already 
pokes directly inside the swap_info_structs, it would be even cleaner to 
use a boolean field within the swap_info_struct.

And if you are using a field within the swap_info_struct, you could 
overload the already existing frontswap_map field, which should only 
have any use if you have a frontswap module already loaded. That is, 
move the vzalloc of the frontswap_map to within frontswap's init 
function, and call it outside the swapfile_lock/swapon_mutex. This also 
has the advantage of not allocating the frontswap_map when it is not 
going to be used.

-- 
Cesar Eduardo Barros
cesarb@cesarb.net
cesar.barros@gmail.com

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  reply	other threads:[~2012-10-31 21:42 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-10-31 15:07 [PATCH 0/5] enable all tmem backends to be built and loaded as modules Dan Magenheimer
2012-10-31 15:07 ` [PATCH 1/5] mm: cleancache: lazy initialization to allow tmem backends to build/run " Dan Magenheimer
2012-11-02 18:29   ` Konrad Rzeszutek Wilk
2012-10-31 15:07 ` [PATCH 2/5] mm: frontswap: " Dan Magenheimer
2012-10-31 17:05   ` Seth Jennings
2012-10-31 21:42     ` Cesar Eduardo Barros [this message]
2012-11-01 15:30     ` Dan Magenheimer
2012-11-02 18:24       ` Konrad Rzeszutek Wilk
2012-11-02 18:27     ` Konrad Rzeszutek Wilk
2012-11-03  1:21       ` Bob Liu
2012-11-14 16:25         ` Konrad Rzeszutek Wilk
2012-10-31 15:07 ` [PATCH 3/5] staging: zcache2+ramster: enable zcache2 to be built/loaded as a module Dan Magenheimer
2012-11-02 18:39   ` Konrad Rzeszutek Wilk
2012-10-31 15:07 ` [PATCH 4/5] staging: zcache2+ramster: enable ramster " Dan Magenheimer
2012-10-31 15:07 ` [PATCH 5/5] xen: tmem: enable Xen tmem shim " Dan Magenheimer

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