From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from tansi.org (ns.km10532-04.keymachine.de [87.118.102.195]) by mail.saout.de (Postfix) with ESMTP for ; Wed, 18 Aug 2010 17:44:22 +0200 (CEST) Received: from gatewagner.dyndns.org (84-74-164-239.dclient.hispeed.ch [84.74.164.239]) by tansi.org (Postfix) with ESMTPA id 13C351218407 for ; Wed, 18 Aug 2010 17:44:21 +0200 (CEST) Date: Wed, 18 Aug 2010 17:44:19 +0200 From: Arno Wagner Message-ID: <20100818154419.GA3349@tansi.org> References: <20100817184635.GA17921@tansi.org> <4C6BC751.10506@redhat.com> <20100818141208.GB1847@tansi.org> <4C6BF27C.1050305@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4C6BF27C.1050305@redhat.com> Subject: Re: [dm-crypt] dm-crypt flush-to-disk freezes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: dm-crypt@saout.de On Wed, Aug 18, 2010 at 04:47:24PM +0200, Milan Broz wrote: > On 08/18/2010 04:12 PM, Arno Wagner wrote: > > On Wed, Aug 18, 2010 at 01:43:13PM +0200, Milan Broz wrote: > >> On 08/17/2010 08:46 PM, Arno Wagner wrote: > >>> The set-up is a dm-crypt partition with a Windows XP > >>> VM and the current VMplayer, all with kernel 2.6.34.4 > >>> from kernel.org and current vmware-tools in the VM. > >> > >> Can you be more specific? > >> > >> You have direct partition with LUKS and this is mapped > >> to vmware directly as disk, right? > >> No fs in the middle? > > > > This is VMwarePlayer. I do not think it even supports putting > > the OS on a partition. So no, there is ext3 in between and the > > VM filesystem Image goes into several 2GB files. > > > > Ah, forgot one possibly important detail: This is dm-crypt on top > > of md RAID1. > > This is quite complex setup... Yes, come to think of it, it is. It is decepticely easy to do however, since the layers all have clean interfaces. > (vmware ws suppported direct access to disk device, it is probably > better setup here. Did they this functionality from player?) No, I do not think so. > I think ext3 part is problem here too, is it using barriers? > (Try to switch them off, it is mount option - just to see if it helps.) Will try that. Thanks. > > Low latency desktop. But the freezes are too long to > > be CPU related and there is heavy disk activity when > > they happen. Therefore mty conclusion that this is > > an emegerncy flush. > > There can be more problems, dm-crypt itself contains cond_resched() > after every encrypted sector allowing decision of scheduler > to switch there. So dm-crypt istelf should not freeze host system this > way, but it doesn't mean that VM suffers from starvation. Good idea. I have not noticed freezes when the focus did not belong to the VM window. Should check that as well, maybe it really is CPU starvation. > I'll check this, I am using similar system, maybe it uncovers some > other problems... > > > Anyways, thanks and I think I will just run the OS unencrypted > > for the moment. The data still goes into the encrypted partition > > and curiously that does not cause problems. Very strange. > > (There is also option to encrypt VM in vmware workstation7 directly. > I wonder if they support it in player :-) Don't think so. At least not in any obvious manner. Arno -- Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno@wagner.name GnuPG: ID: 1E25338F FP: 0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F ---- Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans If it's in the news, don't worry about it. The very definition of "news" is "something that hardly ever happens." -- Bruce Schneier