Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 5 Nov 2001 05:27:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 5 Nov 2001 05:27:40 -0500 Received: from humbolt.nl.linux.org ([131.211.28.48]:21427 "EHLO humbolt.nl.linux.org") by vger.kernel.org with ESMTP id ; Mon, 5 Nov 2001 05:27:30 -0500 Content-Type: text/plain; charset=US-ASCII From: Daniel Phillips To: dalecki@evision.ag, Martin Dalecki , Alexander Viro Subject: Re: PROPOSAL: dot-proc interface [was: /proc stuff] Date: Mon, 5 Nov 2001 11:28:27 +0100 X-Mailer: KMail [version 1.3.2] Cc: Tim Jansen , "Jakob =?iso-8859-1?q?=D8stergaard?=" , linux-kernel@vger.kernel.org In-Reply-To: <3BE672D1.5E4DBFD2@evision-ventures.com> In-Reply-To: <3BE672D1.5E4DBFD2@evision-ventures.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Message-Id: <20011105102724Z16315-18972+86@humbolt.nl.linux.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On November 5, 2001 12:06 pm, Martin Dalecki wrote: > Alexander Viro wrote: > > At the very least, use canonical bytesex and field sizes. Anything less > > is just begging for trouble. And in case of procfs or its equivalents, > > _use_ the_ _damn_ _ASCII_ _representations_. scanf(3) is there for > > purpose. > > And the purpose of scanf in system level applications is to introduce > nice opportunities for buffer overruns and string formatting bugs. I've done quite a bit more kernel profiling and I've found that overhead for converting numbers to ascii for transport to proc is significant, and there are other overheads as well, such as the sprintf and proc file open. These must be matched by corresponding overhead on the user space side, which I have not profiled. I'll take some time and present these numbers properly at some point. Not that I think we are going to change this way of doing things any time soon - Linus has spoken - but at least we should know what the overheads are. Programmers should not labor under the misaprehension that this is an efficient interface. -- Daniel - 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/