From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx176.postini.com [74.125.245.176]) by kanga.kvack.org (Postfix) with SMTP id 24D846B006C for ; Wed, 31 Oct 2012 17:42:58 -0400 (EDT) Message-ID: <50919B5D.9000100@cesarb.net> Date: Wed, 31 Oct 2012 19:42:53 -0200 From: Cesar Eduardo Barros MIME-Version: 1.0 Subject: Re: [PATCH 2/5] mm: frontswap: lazy initialization to allow tmem backends to build/run as modules References: <1351696074-29362-1-git-send-email-dan.magenheimer@oracle.com> <1351696074-29362-3-git-send-email-dan.magenheimer@oracle.com> <50915A5C.8000303@linux.vnet.ibm.com> In-Reply-To: <50915A5C.8000303@linux.vnet.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Seth Jennings Cc: Dan Magenheimer , 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 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org