From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: disable TCQ? Date: Thu, 28 Jun 2007 06:09:02 -0400 Message-ID: <468388BE.6040809@garzik.org> References: <46836F15.2040208@msgid.tls.msk.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:47723 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753530AbXF1KJH (ORCPT ); Thu, 28 Jun 2007 06:09:07 -0400 In-Reply-To: <46836F15.2040208@msgid.tls.msk.ru> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Michael Tokarev Cc: linux-scsi@vger.kernel.org Michael Tokarev wrote: > /sys/block/sdX/device/queue_depth file is read-write with > libsata, but is read-only with SCSI controllers (at least > with the ones we have -- mostly aic7xxx or mptsas). > > Googling for "disable tcq" gives results about {dis,en}abling > TCQ at boot time, and also mentions ipr (which we don't have). > > Is there an option to control TCQ at runtime? You have found the correct sysfs file -- but read/write access to it requires the SCSI driver to implement the ->change_queue_depth() hook. 'grep -w' will show that not too many drivers have implemented this yet, mostly the newer ones. For older drivers, poke around and see if there is a driver-specific module option or somesuch. Jeff