From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758866AbXEJJUy (ORCPT ); Thu, 10 May 2007 05:20:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755880AbXEJJUq (ORCPT ); Thu, 10 May 2007 05:20:46 -0400 Received: from brick.kernel.dk ([80.160.20.94]:22262 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755699AbXEJJUp (ORCPT ); Thu, 10 May 2007 05:20:45 -0400 Date: Thu, 10 May 2007 11:20:17 +0200 From: Jens Axboe To: Mathieu Desnoyers Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, hch@infradead.org Subject: Re: [patch 10/10] Port of blktrace to the Linux Kernel Markers. Message-ID: <20070510092015.GJ4629@kernel.dk> References: <20070510015555.973107048@polymtl.ca> <20070510020918.085866258@polymtl.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070510020918.085866258@polymtl.ca> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 09 2007, Mathieu Desnoyers wrote: > Here is a proof of concept patch, for demonstration purpose, of moving > blktrace to the markers. > > A few remarks : this patch has the positive effect of removing some code > from the block io tracing hot paths, minimizing the i-cache impact in a > system where the io tracing is compiled in but inactive. > > It also moves the blk tracing code from a header (and therefore from the > body of the instrumented functions) to a separate C file. > > There, as soon as one device has to be traced, every devices have to > fall into the tracing function call. This is slower than the previous > inline function which tested the condition quickly. If it becomes a > show stopper, it could be fixed by having the possibility to test a > supplementary condition, dependant of the marker context, at the marker > site, just after the enable/disable test. Did you benchmark it? -- Jens Axboe