From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: dm-crypt parallelization patches Date: Tue, 9 Apr 2013 14:02:01 -0700 Message-ID: <20130409210201.GM6186@mtj.dyndns.org> References: <20130328194443.GG14088@htj.dyndns.org> <20130328203808.GC15969@redhat.com> <20130328204522.GA25501@mtj.dyndns.org> <20130409175753.GA6186@mtj.dyndns.org> <20130409181031.GC6186@mtj.dyndns.org> <20130409195259.GL6186@mtj.dyndns.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Mikulas Patocka Cc: Jens Axboe , Vivek Goyal , Mike Snitzer , Milan Broz , dm-devel@redhat.com, Andi Kleen , dm-crypt@saout.de, linux-kernel@vger.kernel.org, Christoph Hellwig , Christian Schmidt List-Id: dm-devel.ids Hey, On Tue, Apr 09, 2013 at 04:32:28PM -0400, Mikulas Patocka wrote: > > and we probably need to change that to bio_associate_task(). > > Generally, we shouldn't associate bios with "current" task in device > mapper targets. For example suppose that we have two stacked dm-crypt > targets: It only follows the first association so it doesn't matter how many layers it goes through. That said, yeah, there could be situations where @task is availalbe but the bio's already in the hand of a different task. If that's the case, change it to associate_task(@task). > It doesn't work because device mapper on the underlying layers ignores > bi_ioc and bi_css. > > If I make device mapper forward bi_ioc and bi_css to outgoing bios, it > improves performance (from 2:30 to 1:30), but it is still far from > perfect. For testing, copying bi_ioc and bi_css directly is fine but please add another interface to copy those for the actual code. Say, bio_copy_association(@to_bio, @from_bio) or whatever. As for the performance loss, I'm somewhat confident in saying the remaining difference would be from ignoring plugging boundaries. Thanks. -- tejun