Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262393AbVAPCjP (ORCPT ); Sat, 15 Jan 2005 21:39:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262406AbVAPCjP (ORCPT ); Sat, 15 Jan 2005 21:39:15 -0500 Received: from scrub.xs4all.nl ([194.109.195.176]:1992 "EHLO scrub.xs4all.nl") by vger.kernel.org with ESMTP id S262393AbVAPCjA (ORCPT ); Sat, 15 Jan 2005 21:39:00 -0500 Date: Sun, 16 Jan 2005 03:38:44 +0100 (CET) From: Roman Zippel X-X-Sender: roman@scrub.home To: Karim Yaghmour cc: Andi Kleen , Nikita Danilov , linux-kernel@vger.kernel.org, Tom Zanussi Subject: Re: 2.6.11-rc1-mm1 In-Reply-To: <41E899AC.3070705@opersys.com> Message-ID: References: <20050114002352.5a038710.akpm@osdl.org> <20050114103836.GA71397@muc.de> <41E7A7A6.3060502@opersys.com> <41E8358A.4030908@opersys.com> <41E899AC.3070705@opersys.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1320 Lines: 28 Hi, On Fri, 14 Jan 2005, Karim Yaghmour wrote: > > Why should a subsystem care about the details of the buffer management? > > Because it wants to enforce a data format on buffer boundaries. It's interesting to read more about ltt's requirements, but I still think it's possible to leave this work to the relayfs layer. Why not just move the ltt buffer management into relayfs and provide a small library, which extracts the event stream again? Otherwise you have to duplicate this work for every serious relayfs user anyway. Completely abstracting the buffer management would the make whole interface simpler and it would be a lot easier to change without breaking everything. E.g. it would be possible to use per cpu buffers and remove the need for different locking mechanisms, for a good tracing mechanism it's not just important that it's lockless, but also that the cpus don't share cache lines in the fast path. In this regard relayfs/ltt has really still too much overhead and the complex relayfs API isn't really making it easy to fix this. bye, Roman - 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/