From mboxrd@z Thu Jan 1 00:00:00 1970 From: Milan Broz Subject: Re: cmwq and dm-crypt devices? Date: Wed, 03 Nov 2010 14:02:14 +0100 Message-ID: <4CD15D56.1060808@redhat.com> References: <1271958538-11193-1-git-send-email-san@google.com> <4BD08F78.4000701@redhat.com> <4BD099DB.2020108@redhat.com> <20101102220207.GD23680@redhat.com> <4CD12F6E.8040501@kernel.org> <20101103115144.GA18935@basil.fritz.box> <4CD14DF1.90601@redhat.com> <20101103123347.GB18935@basil.fritz.box> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20101103123347.GB18935@basil.fritz.box> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Andi Kleen Cc: Christophe Saout , Mike Snitzer , Brian Swetland , San Mehat , device-mapper development , Tejun Heo , Andrew Morton , Alasdair G Kergon List-Id: dm-devel.ids On 11/03/2010 01:33 PM, Andi Kleen wrote: >> Async crypto is not solved at all by your patch. > > You mean async crypto with 10 stacked devices? Find me a single > user who does that. It is just quick reproducer. It can happen with several non-stacked devices too and just points to the problem that there was reason for dedicated threads per device. I would really prefer If we can fix the scalable problem without dismantling existing stacking support. There are users who plans to massively use many dm-crypt devices in system and this will ensure that it will work properly even in bizarre configurations. > Traditionally stacking didn't work very > well in the kernel due to the limited kernel stack overflows. > I don't think that's significantly different here. Sorry? device-mapper is designed to be stackable. And it works. > Anyways stacking could be probably fixed, but it's also that 99.999999% > of all dm-crypt users don't stack or use async but simply need a > scalable dm-crypt. Extreme stacking is extremly low on the > priority list. > > Right now dm-crypt seems to have other problems anyways that need > to be addressed first. I fixed many bugs in dm-crypt which were caused by reducing problem to "common situation" (and which appeared later). Please can you fix you patch instead of this argumentation? I know that some fix is needed, I am using the patch myself and I am also receiving mails requesting it. The whole thread was reopened because we tried to find solution to this - IOW fix your patch. Milan