From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: [PATCH 4/4] input: dynamically allocate ABS information Date: Wed, 14 Jul 2010 01:18:48 -0700 Message-ID: <20100714081848.GC2712@core.coreip.homeip.net> References: <1274289757-2723-1-git-send-email-daniel@caiaq.de> <1274289757-2723-5-git-send-email-daniel@caiaq.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pw0-f46.google.com ([209.85.160.46]:61485 "EHLO mail-pw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753124Ab0GNISz (ORCPT ); Wed, 14 Jul 2010 04:18:55 -0400 Content-Disposition: inline In-Reply-To: <1274289757-2723-5-git-send-email-daniel@caiaq.de> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Daniel Mack Cc: linux-kernel@vger.kernel.org, linux-input@vger.kernel.org On Wed, May 19, 2010 at 07:22:37PM +0200, Daniel Mack wrote: > > /** > + * input_alloc_absinfo - allocates an input_absinfo struct > + * @dev: the input device > + * @axis: the ABS axis > + * > + * If the absinfo struct the caller asked for is already allocated, this > + * functions will not do anything but return it. > + */ > +struct input_absinfo *input_alloc_absinfo(struct input_dev *dev, int axis) > +{ > + if (!dev->absinfo[axis]) > + dev->absinfo[axis] = > + kzalloc(sizeof(struct input_absinfo), GFP_KERNEL); > + > + WARN(!dev->absinfo[axis], "%s(): kzalloc() failed?\n", __func__); > + return dev->absinfo[axis]; This causes us to allocate every absinfo structure separately and use 64 additional pointers (256 bytes on 32 bit boxes and even more on 64 bit boxes). If device uses enough axis we end up eating up most savings. I think we should simply alloctate ABS_CNT worth of absinfo first time we try to set up abs parameters and be done with it so we'll be saving space for devices not reporting absolute events. Another optionw woudl be to allow drivers specify size of absinfo array but I am not sure if it worth it. Thanks. -- Dmitry