From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753521Ab1IVSci (ORCPT ); Thu, 22 Sep 2011 14:32:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51201 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751370Ab1IVSci (ORCPT ); Thu, 22 Sep 2011 14:32:38 -0400 From: Jeff Moyer To: Christoph Hellwig Cc: jens.axboe@fusionio.com, linux-kernel@vger.kernel.org Subject: Re: blk_classic tracing horribly broken References: <20110922181216.GA13772@infradead.org> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Thu, 22 Sep 2011 14:32:29 -0400 In-Reply-To: <20110922181216.GA13772@infradead.org> (Christoph Hellwig's message of "Thu, 22 Sep 2011 14:12:16 -0400") Message-ID: User-Agent: Gnus/5.110011 (No Gnus v0.11) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Christoph Hellwig writes: > On Thu, Sep 22, 2011 at 01:57:11PM -0400, Jeff Moyer wrote: >> Hi, >> >> I've stared at the code for a while, and I've come up empty. Would >> anyone care to take a stab at fixing this? >> >> To reproduce: >> >> mount -t debugfs none /sys/kernel/debug >> cd /sys/kernel/debug/tracing >> echo blk > current_tracer >> echo 1 > events/block/enable >> echo 1 > options/blk_classic >> echo 1 > tracing_on >> >> dd if=/dev/ of=/dev/null bs=1M count=1 iflag=direct >> cat trace > > Why are you using this interface anyway? We actually had planned to > drop it long time ago, but for some reason that never happened. I was using it when testing the flush+fua reporting in blktrace, to be sure we didn't break it. Since it was already broken, I didn't have to worry, but I put it on my todo list to investigate why. Dropping broken code is fine with me (given that there are two alternatives to use). Cheers, Jeff