From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Triplett Subject: Bug#648367: device-mapper devices such as dm-crypt always have rotational=1; should inherit "rotational" setting from underlying devices Date: Sun, 13 Nov 2011 18:26:44 -0800 Message-ID: <20111114022644.GB30421@leaf> References: <20111110195943.12083.93273.reportbug@leaf> <1321232729.3059.42.camel@deadeye> Reply-To: Josh Triplett , 648367@bugs.debian.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Resent-To: debian-bugs-dist@lists.debian.org Resent-Message-ID: Content-Disposition: inline In-Reply-To: <1321232729.3059.42.camel@deadeye> List-Post: List-Help: List-Subscribe: List-Unsubscribe: To: Ben Hutchings Cc: 648367@bugs.debian.org, dm-devel@redhat.com List-Id: dm-devel.ids On Mon, Nov 14, 2011 at 01:05:29AM +0000, Ben Hutchings wrote: > On Thu, 2011-11-10 at 11:59 -0800, Josh Triplett wrote: > > Source: linux-2.6 > > Version: 3.1.0-1~experimental.1 > > Severity: normal > > > > I use dm-crypt on my system, and I have an SSD. The underlying disk > > device, sda, has rotational=0: > > > > ~$ cat /sys/block/sda/queue/rotational > > 0 > > > > However, the device-mapper devices have rotational=1: > > > > ~$ head /sys/block/dm-*/queue/rotational > > ==> /sys/block/dm-0/queue/rotational <== > > 1 > > > > ==> /sys/block/dm-1/queue/rotational <== > > 1 > > > > ==> /sys/block/dm-2/queue/rotational <== > > 1 > > > > The device-mapper devices should inherit the setting for "rotational" > > from their underlying devices. > > I'm not sure that's true. Since their queues should feed into the > queues for the underlying devices, it may be that they shouldn't > themselves be scheduled as if they are rotating media. OK, I suppose I don't actually care what rotational shows for a device-mapper device backed by rotating media. The case I care about: when the underlying media has rotational=0, the dm device definitely shouldn't have rotational=1. - Josh Triplett