From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Martin K. Petersen" Subject: Re: [PATCHv5 00/14] dm-zoned: metadata version 2 Date: Wed, 13 May 2020 20:20:28 -0400 Message-ID: References: <20200508090332.40716-1-hare@suse.de> <2553e593-795d-6aed-f983-e990a283e2ff@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: (Damien Le Moal's message of "Wed, 13 May 2020 23:56:23 +0000") List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Damien Le Moal Cc: Bob Liu , "dm-devel@redhat.com" , Mike Snitzer , "Martin K . Petersen" List-Id: dm-devel.ids Damien, > Any idea why the io_opt limit is not set to the physical block size > when the drive does not report an optimal transfer length ? Would it > be bad to set that value instead of leaving it to 0 ? The original intent was that io_opt was a weak heuristic for something being a RAID device. Regular disk drives didn't report it. These days that distinction probably isn't relevant. However, before we entertain departing from the historic io_opt behavior, I am a bit puzzled by the fact that you have a device that reports io_opt as 512 bytes. What kind of device performs best when each I/O is limited to a single logical block? -- Martin K. Petersen Oracle Linux Engineering