From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by mail.saout.de (Postfix) with ESMTP for ; Thu, 21 Apr 2011 20:06:28 +0200 (CEST) Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p3LI6Q3O009836 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Thu, 21 Apr 2011 14:06:26 -0400 Received: from [10.34.26.53] (tawny.brq.redhat.com [10.34.26.53]) by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id p3LI6Px8014151 for ; Thu, 21 Apr 2011 14:06:26 -0400 Message-ID: <4DB07221.6020708@redhat.com> Date: Thu, 21 Apr 2011 20:06:25 +0200 From: Milan Broz MIME-Version: 1.0 References: <20110421171448.GC15599@mail.randallcotton.com> <20110421175202.GA17024@tansi.org> In-Reply-To: <20110421175202.GA17024@tansi.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit 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 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. Milan