From: Jens Axboe Subject: Re: [PATCH v3 1/2] block: skip elevator data initialization for flush requests Date: Thu, 3 Feb 2011 14:24:42 +0100 Message-ID: <4D4AAC9A.4050407@fusionio.com> References: <20110201185225.GT14211@htj.dyndns.org> <1296600373-6906-1-git-send-email-snitzer@redhat.com> <20110202225549.GA28109@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Cc: Tejun Heo , "tytso@mit.edu" , "djwong@us.ibm.com" , "shli@kernel.org" , "neilb@suse.de" , "adilger.kernel@dilger.ca" , "jack@suse.cz" , "linux-kernel@vger.kernel.org" , "kmannth@us.ibm.com" , "cmm@us.ibm.com" , "linux-ext4@vger.kernel.org" , "rwheeler@redhat.com" , "hch@lst.de" , "josef@redhat.com" , "jmoyer@redhat.com" , "vgoyal@redhat.com" To: Mike Snitzer Return-path: In-Reply-To: <20110202225549.GA28109@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On 2011-02-02 23:55, Mike Snitzer wrote: > Set REQ_SORTED, in the @rw_flags passed to the request allocator, for > any request that may be put on IO scheduler. Skip elevator data > initialization during request allocation if REQ_SORTED is not set. > > REQ_SORTED is not set for flush requests because they are never put on > the IO scheduler. That looks very wrong. REQ_SORTED gets set _when_ the request is sorted into the IO scheduler. This is gross misuse, a bad hack. -- Jens Axboe