<tt>Hi Martin,</tt> In your case, my action is: 1) merger uevents 1) 2) to one uevent "add sda sdb", and process them togother 2) process uevent "del sda" 3) process uevent "add sdc" 4) process uevent "del sdb" 5) process uevent "add sda" Though the processing efficiency in such scenario is lower than yours, but it is simple and reliable, <div>more importantly, Martin, you still focus on such special scene, which I concerned is like this: UDEV [19172.014482] add /devices/platform/host3/session17/target3:0:0/3:0:0:0/block/sdc (block) UDEV [19172.249389] add /devices/platform/host4/session18/target4:0:0/4:0:0:0/block/sdd (block) UDEV [19172.343791] add /devices/platform/host3/session17/target3:0:0/3:0:0:2/block/sdf (block) UDEV [19172.364496] add /devices/platform/host5/session19/target5:0:0/5:0:0:0/block/sdh (block) UDEV [19172.523794] add /devices/platform/host4/session18/target4:0:0/4:0:0:2/block/sdi (block) UDEV [19172.621333] add /devices/platform/host3/session17/target3:0:0/3:0:0:4/block/sdn (block) UDEV [19172.699473] add /devices/platform/host4/session18/target4:0:0/4:0:0:1/block/sdg (block) UDEV [19172.704605] add /devices/platform/host3/session17/target3:0:0/3:0:0:1/block/sde (block) UDEV [19172.709687] add /devices/platform/host3/session17/target3:0:0/3:0:0:3/block/sdj (block) UDEV [19172.714919] add /devices/platform/host4/session18/target4:0:0/4:0:0:3/block/sdl (block) UDEV [19172.728891] add /devices/platform/host4/session18/target4:0:0/4:0:0:4/block/sdo (block) UDEV [19172.872156] add /devices/platform/host3/session17/target3:0:0/3:0:0:6/block/sdt (block) UDEV [19172.915542] add /devices/platform/host4/session18/target4:0:0/4:0:0:6/block/sdu (block) UDEV [19173.086935] add /devices/platform/host6/session20/target6:0:0/6:0:0:0/block/sdw (block) UDEV [19173.108278] add /devices/platform/host6/session20/target6:0:0/6:0:0:1/block/sdz (block) UDEV [19173.195153] add /devices/platform/host4/session18/target4:0:0/4:0:0:5/block/sdr (block) UDEV [19173.228397] add /devices/platform/host3/session17/target3:0:0/3:0:0:5/block/sdq (block) UDEV [19173.363632] add /devices/platform/host5/session19/target5:0:0/5:0:0:2/block/sdm (block) UDEV [19173.386560] add /devices/platform/host3/session17/target3:0:0/3:0:0:7/block/sdx (block) UDEV [19173.394515] add /devices/platform/host4/session18/target4:0:0/4:0:0:7/block/sdy (block) UDEV [19173.410152] add /devices/platform/host5/session19/target5:0:0/5:0:0:1/block/sdk (block) UDEV [19173.474286] add /devices/platform/host6/session20/target6:0:0/6:0:0:2/block/sdab (block) UDEV [19173.508438] add /devices/platform/host5/session19/target5:0:0/5:0:0:3/block/sdp (block) UDEV [19173.713146] add /devices/platform/host5/session19/target5:0:0/5:0:0:4/block/sds (block) UDEV [19173.782065] add /devices/platform/host5/session19/target5:0:0/5:0:0:5/block/sdv (block) UDEV [19173.787447] add /devices/platform/host5/session19/target5:0:0/5:0:0:6/block/sdaa (block) UDEV [19173.803218] add /devices/platform/host6/session20/target6:0:0/6:0:0:3/block/sdad (block) UDEV [19173.849411] add /devices/platform/host5/session19/target5:0:0/5:0:0:7/block/sdac (block) UDEV [19173.918301] add /devices/platform/host6/session20/target6:0:0/6:0:0:5/block/sdaf (block) UDEV [19173.941005] add /devices/platform/host6/session20/target6:0:0/6:0:0:4/block/sdae (block) UDEV [19173.987206] add /devices/platform/host6/session20/target6:0:0/6:0:0:7/block/sdah (block) UDEV [19173.992431] add /devices/platform/host6/session20/target6:0:0/6:0:0:6/block/sdag (block) Or like this: UDEV [20712.402631] remove /devices/platform/host3/session17/target3:0:0/3:0:0:0/block/sdc (block) UDEV [20712.427716] remove /devices/platform/host6/session20/target6:0:0/6:0:0:0/block/sdw (block) UDEV [20712.459854] remove /devices/platform/host4/session18/target4:0:0/4:0:0:0/block/sdd (block) UDEV [20712.471124] remove /devices/platform/host5/session19/target5:0:0/5:0:0:0/block/sdh (block) UDEV [20712.492190] remove /devices/platform/host6/session20/target6:0:0/6:0:0:1/block/sdz (block) UDEV [20712.495245] remove /devices/platform/host4/session18/target4:0:0/4:0:0:1/block/sdg (block) UDEV [20712.512007] remove /devices/platform/host3/session17/target3:0:0/3:0:0:1/block/sde (block) UDEV [20712.522986] remove /devices/platform/host5/session19/target5:0:0/5:0:0:1/block/sdk (block) UDEV [20712.528676] remove /devices/platform/host6/session20/target6:0:0/6:0:0:2/block/sdab (block) UDEV [20712.529891] remove /devices/platform/host5/session19/target5:0:0/5:0:0:2/block/sdm (block) UDEV [20712.536178] remove /devices/platform/host4/session18/target4:0:0/4:0:0:2/block/sdi (block) UDEV [20712.545444] remove /devices/platform/host4/session18/target4:0:0/4:0:0:3/block/sdl (block) UDEV [20712.548006] remove /devices/platform/host3/session17/target3:0:0/3:0:0:3/block/sdj (block) UDEV [20712.551935] remove /devices/platform/host5/session19/target5:0:0/5:0:0:3/block/sdp (block) UDEV [20712.555405] remove /devices/platform/host3/session17/target3:0:0/3:0:0:2/block/sdf (block) UDEV [20712.556947] remove /devices/platform/host4/session18/target4:0:0/4:0:0:4/block/sdo (block) UDEV [20712.563524] remove /devices/platform/host5/session19/target5:0:0/5:0:0:4/block/sds (block) UDEV [20712.572948] remove /devices/platform/host6/session20/target6:0:0/6:0:0:4/block/sdae (block) UDEV [20712.574738] remove /devices/platform/host6/session20/target6:0:0/6:0:0:3/block/sdad (block) UDEV [20712.576736] remove /devices/platform/host4/session18/target4:0:0/4:0:0:5/block/sdr (block) UDEV [20712.581343] remove /devices/platform/host3/session17/target3:0:0/3:0:0:4/block/sdn (block) UDEV [20712.583883] remove /devices/platform/host3/session17/target3:0:0/3:0:0:5/block/sdq (block) UDEV [20712.604498] remove /devices/platform/host6/session20/target6:0:0/6:0:0:5/block/sdaf (block) UDEV [20712.605536] remove /devices/platform/host4/session18/target4:0:0/4:0:0:6/block/sdu (block) UDEV [20712.605721] remove /devices/platform/host3/session17/target3:0:0/3:0:0:6/block/sdt (block) UDEV [20712.606517] remove /devices/platform/host5/session19/target5:0:0/5:0:0:5/block/sdv (block) UDEV [20712.610709] remove /devices/platform/host5/session19/target5:0:0/5:0:0:6/block/sdaa (block) UDEV [20712.618187] remove /devices/platform/host4/session18/target4:0:0/4:0:0:7/block/sdy (block) UDEV [20712.628520] remove /devices/platform/host6/session20/target6:0:0/6:0:0:6/block/sdag (block) UDEV [20712.642216] remove /devices/platform/host5/session19/target5:0:0/5:0:0:7/block/sdac (block) UDEV [20712.643796] remove /devices/platform/host3/session17/target3:0:0/3:0:0:7/block/sdx (block) UDEV [20712.653786] remove /devices/platform/host6/session20/target6:0:0/6:0:0:7/block/sdah (block) These scenarios are more realistic and more urgently requested to be solved. <tt>Regards, Tang</tt> <div> 发件人: Martin Wilck <mwilck@suse.com> 收件人: tang.junhui@zte.com.cn, 抄送: dm-devel@redhat.com 日期: 2016/11/18 15:40 主题: Re: Re: [dm-devel] Improve processing efficiency for addition and deletion of multipath devices <hr noshade> <tt>Hi Tang, On Fri, 2016-11-18 at 09:02 +0800, tang.junhui@zte.com.cn wrote: > > we are more concerned > about the more common situation like addition or deletion devices > when > iSCSI login/logout or FC link up/down with many iSCSI or FC links > in > each LUN. At this situation we may receive many uevents from > different > paths of the same LUN device, we want merge these uevents to one > and > process them together. I'm not arguing against that. But consider what you'd do if you have to process the series of uevents [ 1 "add sda", 2 "add sdb", 3 "del sda", 4 "add sdc", 5 "del sdb", 6 "add sda" ]. If you merge these, assuming all belong to the same multipath map, what would be your action? I would set up a map with sda and sdc, using the device properties from event 4 and 6. That means that the rest of the events has been "filtered" out. All else would mean repeated map loads for the same multipath map, which is what we want to avoid. Agreed? Regards, Martin -- Dr. Martin Wilck <mwilck@suse.com>, Tel. +49 (0)911 74053 2107 SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton HRB 21284 (AG Nürnberg) </tt> </div></div>