From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH] block: add missing block_bio_complete() tracepoint Date: Sun, 29 Jan 2012 17:47:03 -0800 Message-ID: <20120130014703.GG17211@htj.dyndns.org> References: <1327830093-12130-1-git-send-email-namhyung@gmail.com> <20120129192447.GB17211@htj.dyndns.org> <4F25F5F3.6060507@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <4F25F5F3.6060507@gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: Namhyung Kim Cc: Jens Axboe , linux-kernel@vger.kernel.org, Steven Rostedt , dm-devel@redhat.com List-Id: dm-devel.ids On Mon, Jan 30, 2012 at 10:44:19AM +0900, Namhyung Kim wrote: > The userland tool cannot distinguish bounced bio from original one > at completion TP, but it can expect there will be a duplicated > BLK_TA_COMPLETE as it sees BLK_TA_BOUNCE for the bio before. > > Filtering it out from kernel side seems to hide a real information > that (paranoid?) user might want to get, and it looks like providing > "polcy not mechanism" IMHO. That's why I changed my mind finally. > > I cannot think of the downside, anyway it's not a big deal, if you > think it's wrong choice, I'm OK to change it again. It's just that this patch as it stands will break the existing tools and is likely to cause some amount of head scratching for blktrace users upgrading to new kernel with existing userland, so yeah, I think it should be filtered in kernel from blktrace.c. Thanks. -- tejun