Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S266892AbUIASIn (ORCPT ); Wed, 1 Sep 2004 14:08:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267359AbUIASFz (ORCPT ); Wed, 1 Sep 2004 14:05:55 -0400 Received: from mail.tmr.com ([216.238.38.203]:50441 "EHLO gatekeeper.tmr.com") by vger.kernel.org with ESMTP id S266892AbUIASF1 (ORCPT ); Wed, 1 Sep 2004 14:05:27 -0400 To: linux-kernel@vger.kernel.org Path: not-for-mail From: Bill Davidsen Newsgroups: mail.linux-kernel Subject: Re: f_ops flag to speed up compatible ioctls in linux kernel Date: Wed, 01 Sep 2004 14:06:16 -0400 Organization: TMR Associates, Inc Message-ID: References: <20040901072245.GF13749@mellanox.co.il><20040901072245.GF13749@mellanox.co.il> <20040901073218.GQ16297@parcelfarce.linux.theplanet.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Trace: gatekeeper.tmr.com 1094061526 17277 192.168.12.100 (1 Sep 2004 17:58:46 GMT) X-Complaints-To: abuse@tmr.com User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.2) Gecko/20040803 X-Accept-Language: en-us, en In-Reply-To: <20040901073218.GQ16297@parcelfarce.linux.theplanet.co.uk> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1714 Lines: 38 viro@parcelfarce.linux.theplanet.co.uk wrote: > On Wed, Sep 01, 2004 at 10:22:45AM +0300, Michael S. Tsirkin wrote: > >>Hello! >>Currently, on the x86_64 architecture, its quite tricky to make >>a char device ioctl work for an x86 executables. >>In particular, >> 1. there is a requirement that ioctl number is unique - >> which is hard to guarantee especially for out of kernel modules > > > Too bad. > > >> 2. there's a performance huge overhead for each compat call - there's >> a hash lookup in a global hash inside a lock_kernel - >> and I think compat performance *is* important. >> >>Further, adding a command to the ioctl suddenly requires changing >>two places - registration code and ioctl itself. > > > So don't add them. Adding a new ioctl is *NOT* a step to be taken lightly - > we used to be far too accepting in that area and as somebody who'd waded > through the resulting dungpiles over the last months I can tell you that > result is utterly revolting. > > Excuse me, but I have zero sympathy to people who complain about obstacles > to dumping more into the same piles - it should be hard. I don't think he was complaining so much as providing a rationale for the patch he offered which is intended to make things better. Seemed to me like a good context for the patch. -- -bill davidsen (davidsen@tmr.com) "The secret to procrastination is to put things off until the last possible moment - but no longer" -me - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/