** Changed in: linux (Ubuntu Bionic)
       Status: In Progress => Fix Committed

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  hisi_sas: improve performance by optimizing DQ locking

Status in linux package in Ubuntu:
  In Progress
Status in linux source package in Bionic:
  Fix Committed

Bug description:
  The way the driver deals with locking the DQ causes performance to suffer.

  [Test Case]
  Run iozone3 and validate performance is >= previous.

  Once a DQ slot is allocated, it must be used. So, currently the driver locks 
the DQ while it builds and sends each task to the hardware, just in case there 
is a failure, so that it can reuse that slot. However - there is a point at 
which we the build/send is guaranteed to succeed, so we can release the lock at 
that point allowing new slots to be allocated.

  [Regression Risk]
  All fixes are localized to the hisi_sas drivers, which are drivers for the 
controllers in the hip06/hip07 SoCs, where we have directly tested these 

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