From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arne Redlich Subject: Re: [Scst-devel] [PATCH 2.6.25.1] Add scsi_execute_async_fifo() Date: Thu, 08 May 2008 17:54:03 +0200 Message-ID: <1210262043.12678.9.camel@blackadder> References: <200805021638.42972.bart.vanassche@gmail.com> <20080502153306.GB7376@infradead.org> <20080502155525.GA16353@infradead.org> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from pow-web.powerkom-dd.de ([212.80.237.131]:55223 "EHLO mail.powerkom-dd.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753186AbYEHQ2w (ORCPT ); Thu, 8 May 2008 12:28:52 -0400 In-Reply-To: Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Bart Van Assche Cc: Christoph Hellwig , James Bottomley , scst-devel@lists.sourceforge.net, Vladislav Bolkhovitin , linux-scsi@vger.kernel.org Am Donnerstag, den 08.05.2008, 17:02 +0200 schrieb Bart Van Assche: > On Sun, May 4, 2008 at 5:30 PM, Bart Van Assche > wrote: > > On Fri, May 2, 2008 at 5:55 PM, Christoph Hellwig wrote: > >> On Fri, May 02, 2008 at 05:53:22PM +0200, Bart Van Assche wrote: > >>> Regarding scsi_execute_async(): I didn't know that this API is on its > >>> way out. What will it be replaced by, and when ? > >> > >> blk_execute_rq/blk_execute_rq_nowait plus the block level helpers built > >> ontop to build requests. > > > > Source reading learned me that the function scsi_execute_async() calls > > blk_execute_rq_nowait() with 1 as fourth argument, which means that > > the request is inserted at the head of the queue. This means that > > requests queued with scsi_execute_async() are executed before other > > queued requests, and that this function has LIFO (last in first out) > > semantics. > > > > All non-SCSI calls to blk_execute_rq() / blk_execute_rq_nowait() add > > requests at the end of the queue (except those calls for terminating > > I/O). > > > > What is the background of this special behavior of the SCSI subsystem ? > > Is the linux-scsi mailing list the appropriate mailing list to post > questions like the above ? I guess this should http://marc.info/?l=linux-scsi&m=116668527804801&w=2 answer your question. HTH, Arne