Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762287AbZATSY2 (ORCPT ); Tue, 20 Jan 2009 13:24:28 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753237AbZATSYU (ORCPT ); Tue, 20 Jan 2009 13:24:20 -0500 Received: from mx2.redhat.com ([66.187.237.31]:43884 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752152AbZATSYT (ORCPT ); Tue, 20 Jan 2009 13:24:19 -0500 Date: Tue, 20 Jan 2009 16:23:57 -0200 From: Arnaldo Carvalho de Melo To: Steven Rostedt Cc: Jens Axboe , Ingo Molnar , Frederic Weisbecker , linux-kernel@vger.kernel.org Subject: Re: [RFC][PATCHv2] ftrace interface for blktrace Message-ID: <20090120182357.GN690@ghostprotocols.net> Mail-Followup-To: Arnaldo Carvalho de Melo , Steven Rostedt , Jens Axboe , Ingo Molnar , Frederic Weisbecker , linux-kernel@vger.kernel.org References: <20090116181611.GE6562@ghostprotocols.net> <20090117190913.GA17722@elte.hu> <20090117191430.GA30821@kernel.dk> <20090117200804.GJ6562@ghostprotocols.net> <20090120144219.GH690@ghostprotocols.net> <20090120175835.GM690@ghostprotocols.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090120175835.GM690@ghostprotocols.net> X-Url: http://oops.ghostprotocols.net:81/blog User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1473 Lines: 38 Em Tue, Jan 20, 2009 at 03:58:35PM -0200, Arnaldo Carvalho de Melo escreveu: > Em Tue, Jan 20, 2009 at 12:03:17PM -0500, Steven Rostedt escreveu: > > > @@ -163,23 +206,33 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes, > > > > > > t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len); > > > > Do we still use relay? > > blkFtrace is an addition to the existing method for the moment, as soon > as we're all satisfied with functionality + performance, we may then > remove that code. I guess that is not a clear answer, so lemme try again: The relay code is only used if the old method of starting a blk trace and setting up filters is used, i.e. the IOCTL method. When we use the sysfs interface to do that we do not use the relay code at all. But most of the rest is shared. Except for things like __trace_note_message and the interface provided by the old blktrace code to insert annotations into the stream. That will be provided by using standard ftrace methods such as /t/trace_marker, as demonstrated by: [root@f10-1 ~]# cat /t/trace_pipe & echo "bye, bye relay" > /t/trace_marker [1] 1090 [root@f10-1 ~]# bash-957 [000] 14727.302000: 0: bye, bye relay - Arnaldo -- 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/