[dm-devel] Improve processing efficiency for addition and deletion of multipath devices

[Martin Wilck]

Hi Tang,

> As to process several uevents for the same physical devices, I think
> the opinions 
> different between us is "FILTER" or "MERGER". Personally, I think
> Merger is more 
> accuracy, for example, we receive 4 paths addition uevent messages
> from the same 
> physical devices: 
> 1)uevent add sdb 
> 2)uevent add sdc 
> 3)uevent add sdd 
> 4)uevent add sde 
> 
> We cannot just filter the 1)2)3) uevent messages but only process the
> 4)uevent message, 
> which would cause losing paths of this multipath devices. 

Of course. My "filtering" idea was meant for cases where several events
for the same device are queued, e.g.

  1) add sda
  2) change sda
  3) delete sda

Is it always sufficient to look only at the last event in such a case?
I think so, but I'm not 100% certain.

Regards
Martin