From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Date: Thu, 30 Oct 2008 13:59:43 +0000 Subject: Re: blktrace and dm devices? Message-Id: <20081030135943.GU31673@kernel.dk> List-Id: References: <1225374971.4431.5.camel@kitka.ibm.com> In-Reply-To: <1225374971.4431.5.camel@kitka.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-btrace@vger.kernel.org On Thu, Oct 30 2008, Martin Peschke wrote: > Hi, > > I have noticed that I get C traces but no D traces for device mapper > devices. Is blktrace supposed to handle dm devices as well? The dispatch event is associated with request dispatching, which dm/md does not do. You should get redirect events, telling you when the IO is being redirected to the bottom device. Or split events. -- Jens Axboe