From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from v4.tansi.org (ns.km33513-03.keymachine.de [87.118.94.3]) by mail.saout.de (Postfix) with ESMTP for ; Thu, 21 Apr 2011 22:26:48 +0200 (CEST) Received: from gatewagner.dyndns.org (84-74-164-52.dclient.hispeed.ch [84.74.164.52]) by v4.tansi.org (Postfix) with ESMTPA id 1350C20566A for ; Thu, 21 Apr 2011 22:26:48 +0200 (CEST) Date: Thu, 21 Apr 2011 22:26:47 +0200 From: Arno Wagner Message-ID: <20110421202647.GA20092@tansi.org> References: <20110421171448.GC15599@mail.randallcotton.com> <20110421175202.GA17024@tansi.org> <4DB07221.6020708@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4DB07221.6020708@redhat.com> Subject: Re: [dm-crypt] dm-crypt kills NFS performance? List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: dm-crypt@saout.de On Thu, Apr 21, 2011 at 08:06:25PM +0200, Milan Broz wrote: > On 04/21/2011 07:52 PM, Arno Wagner wrote: > > > > This sounds like one more problems with the Big Kernel Lock. > > The basic problem (simplified) is that some operations > > block everything while running. dm-crypt and RAID makes > > them take longer, but the problem is the blocking. > > It can be many problems, from network card driver to > nfs handling or io scheduler setting. > > For dm-crypt (kcryptd) - it doesn't not use BKL at all > and after every sector encryption it calls cond_resched() > (hinting scheduler to switch process if there is other work > even if kernel is compiled with voluntary preemption). > So it should behave correctly under load. Ah. Good to know. 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