git: nvme - Add interrupt coalescing support

[Matthew Dillon]

commit 23bba4b51cd8cfd346a72004221300ec50fc7ae6
Author: Matthew Dillon <dillon at apollo.backplane.com>
Date:   Tue Jun 7 22:30:00 2016 -0700

    nvme - Add interrupt coalescing support
    
    * Add interrupt coalescing support.  However, disable it in the code for
      now by setting its parameters to 0.  I tried minimal parameters (time
      set to 1 which is 100uS and aggregation threshold set to 4) and it
      completely destroyed performance in all my tests on the Intel 750.
    
      Even in tests where the interrupt rate was less than 10,000/sec, the
      intel controller is clearly implementing a broken algorithm and is
      actually enforcing that 100uS of latency even if the interrupt rate
      has not exceeded the rate.  So even relatively large transfers had
      horrible performance.
    
      So for now the code is in, but its turned off.

Summary of changes:
 sys/dev/disk/nvme/nvme_admin.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/23bba4b51cd8cfd346a72004221300ec50fc7ae6


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