From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <4BE27123.6070501@gmail.com> Date: Thu, 06 May 2010 09:34:59 +0200 From: Xose Vazquez Perez MIME-Version: 1.0 Subject: Re: deadline ALWAYS default for dasd devices(s390) ? References: <4BD58848.8090205@gmail.com> <20100505061620.GA2381@osiris.boeblingen.de.ibm.com> <4BE123B1.1050500@linux.vnet.ibm.com> In-Reply-To: <4BE123B1.1050500@linux.vnet.ibm.com> Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: Stefan Weinhuber Cc: Heiko Carstens , Stefan Weinhuber , Horst Hummel , Stefan Haberland , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org List-ID: On 05/05/2010 09:52 AM, Stefan Weinhuber wrote: hi, > At the time this change was made we had the problem that the > default scheduler chosen by the distributions resulted in > bad performance for DASD devices. Have you done recently new cfq vs. deadline tests, in z/VM and LPAR ? > I agree that hard coding this choice into the driver is not pretty, > but it is pragmatic.=20 It's awful. Easier and simpler from user space: /sys/block/dasdX/queue/sche= duler > Some generic mechanism for setting driver specific > defaults would be nicer, but I doubt that many other drivers would > actually benefit from such an interface. see s390-tools-1.8.4/etc/udev/rules.d/60-readahead.rules That's the way to do it. -thanks- --=20 =ABAll=E1 muevan feroz guerra, ciegos reyes por un palmo m=E1s de tierra; que yo aqu=ED tengo por m=EDo cuanto abarca el mar brav=EDo, a quien nadie impuso leyes. Y no hay playa, sea cualquiera, ni bandera de esplendor, que no sienta mi derecho y d=E9 pecho a mi valor.=BB