From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 30 May 2018 01:47:53 -0700 From: Christoph Hellwig To: Damien Le Moal Cc: Jens Axboe , Jeff Moyer , "linux-block@vger.kernel.org" , "bgurney@redhat.com" Subject: Re: [PATCH 0/2][RFC] block: default to deadline for SMR devices Message-ID: <20180530084753.GA29413@infradead.org> References: <20180525211432.20359-1-jmoyer@redhat.com> <9756f816-cea7-52cc-e616-54cd7b7d8c75@kernel.dk> <122bc1d9-a074-7282-6812-aba26f4868f4@wdc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <122bc1d9-a074-7282-6812-aba26f4868f4@wdc.com> List-ID: On Wed, May 30, 2018 at 06:22:04AM +0000, Damien Le Moal wrote: > That would necessitate splitting elevator_init() into a generic elevator > initialization function setting up the elevator related fields of the > request queue and a second part setting up the default elevator (e.g. > elevator_set_default()). Doing so, the function elevator_set_default() > could be called later in the device initialization sequence, after > information from the device has been obtained. It would make choosing a > sane default elevator much cleaner. For blk-mq this makes entirely sense, untested series here: http://git.infradead.org/users/hch/block.git/shortlog/refs/heads/elevator_init For the legacy case we always need at least some I/O scheduler, so we can't just defer it. But I think we could still switch to deadline in blk_register_queue if we found a zoned device.