From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: sg driver and Fedora Core 2 Date: Sat, 29 May 2004 13:58:12 -0400 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <40B8CF34.6080901@pobox.com> References: <40B74725.90403@torque.net> <20040528172535.GD13961@devserv.devel.redhat.com > <1085846125.2101.29.camel@mulgrave> <20040529155744.GA32621@devserv.devel. redhat.com> <1085846840.2103.47.camel@mulgrave> <20040529162912.GA5922@devserv.devel.redhat.com> <1085849399.2004.101.camel@mulgrave> <40B8C81E.3050106@pobox.com> <1085852299.2004.206.camel@mulgrave> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:52436 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id S264477AbUE2R60 (ORCPT ); Sat, 29 May 2004 13:58:26 -0400 In-Reply-To: <1085852299.2004.206.camel@mulgrave> List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: SCSI Mailing List , Alan Cox , Douglas Gilbert , Arjan van de Ven , Jens Axboe James Bottomley wrote: > On Sat, 2004-05-29 at 12:27, Jeff Garzik wrote: > >>Really what needs to happen is a generic userland tap attaches to a >>chrdev, issues an ioctl(2) to attach to a request_queue, and then does >>read(2)/write(2)/mmap(2) to communicate with the request_queue. >> >>:) >> >>Call it /dev/bsg, or somesuch. > > > Well, this touches on something else I'm thinking about: lazy > attachment. In multi thousand disc environments, you don't want us > wasting resources allocating a queue and reading a partition table for > all of them; you really only want to do that for the devices you're > actually going to use. Once we have this, I think dual attachment will > be a dead issue. Regardless of lazy attachment, request_queues need to support multiple simultaneous producers of struct request's. Jeff