From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Snitzer Subject: Re: DM MULTIPATH: Allow dm to send larger request if underlying device set to larger max_sectors value Date: Mon, 9 Jul 2012 09:00:52 -0400 Message-ID: <20120709130052.GC30048@redhat.com> References: Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: "Chauhan, Vijay" Cc: "dm-devel@redhat.com" , "Moger, Babu" , "Stankey, Robert" List-Id: dm-devel.ids On Sun, Jul 08 2012 at 1:59pm -0400, Chauhan, Vijay wrote: > Even though underlying paths are set with larger value for max_sectors, dm > sets 1024(i.e 512KB) for max_sectors as default. max_sectors for dm > device can be reset through sysfs but any time map is updated, max_sectors > is again set back to default. This patch gets the minimum of max_sectors from > physical paths and sets it to dm device. There shouldn't be any need for additional DM overrides for max_sectors. DM will stack the limits for all underlying devices each table reload (via dm_calculate_queue_limits). And max_sectors is properly stacked in the block layer's bdev_stack_limits (called by dm_set_device_limits). So is something resetting max_sectors with sysfs? multipathd? Mike