From owner-freebsd-current@FreeBSD.ORG Sat Nov 29 18:30:53 2008 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 9AFEC1065686 for ; Sat, 29 Nov 2008 18:30:53 +0000 (UTC) (envelope-from marius@nuenneri.ch) Received: from mail-gx0-f19.google.com (mail-gx0-f19.google.com [209.85.217.19]) by mx1.freebsd.org (Postfix) with ESMTP id 591FF8FC20 for ; Sat, 29 Nov 2008 18:30:53 +0000 (UTC) (envelope-from marius@nuenneri.ch) Received: by gxk12 with SMTP id 12so675207gxk.19 for ; Sat, 29 Nov 2008 10:30:52 -0800 (PST) Received: by 10.90.83.18 with SMTP id g18mr5115218agb.68.1227983452593; Sat, 29 Nov 2008 10:30:52 -0800 (PST) Received: by 10.90.73.15 with HTTP; Sat, 29 Nov 2008 10:30:52 -0800 (PST) Message-ID: Date: Sat, 29 Nov 2008 19:30:52 +0100 From: "=?ISO-8859-1?Q?Marius_N=FCnnerich?=" To: "Alexander Leidinger" In-Reply-To: <20081129184431.7a201a3a@deskjail> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline References: <20081128154514.82247fe47bn83lkw@webmail.leidinger.net> <20081128172126.453467ea7w6jb5c8@webmail.leidinger.net> <20081129184431.7a201a3a@deskjail> Cc: freebsd-current@freebsd.org Subject: Re: HOWTO in wiki: adding custom dtrace probes in the kernel X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 29 Nov 2008 18:30:53 -0000 On Sat, Nov 29, 2008 at 6:44 PM, Alexander Leidinger wrote: > Quoting "Marius N=FCnnerich" (Fri, 28 Nov 2008 19:47= :21 +0100): > >> What is the intention of adding function entry and return providers >> with SDT? Isn't that what FBT is for? > > To make it more easy for the dtrace script writter. If you want to > trace all linuxulator specific stuff, you can use the wildcard > linuxulator:::entry { ... } > > Or if you want to trace everything specific to linux file related stuff > you use the wildcard > linuxulator:file::entry { ... } > > With the fbt, this is much more difficult to do. You have to find out > all related functions and specify them. This may not be hard for a > kernel developer, but an user with a problem just wants to solve the > problem, and getting an idea what is going on is more easy with the > entry and return probes from the sdt, as they have a more narrow > semantic meaning than the similar probe from the fbt (the fbt just > tells you it's a kernel function, whereas the linuxulator probe > provides you with the information that it is a function which belongs > to the linuxulator and it's corresponding module grouping (like file > related, ioctl related, ...)). No need to hunt down this info in the > kernel yourself. Many thanks for your explanation. That makes sense to me.