OS-73 do not do IO completions in the ISR
NEX-1889 mpt_sas should support 12G HBAs

@@ -20,10 +20,11 @@
 #
 #
 # Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 # Use is subject to license terms.
 #
+# Copyright 2014 Nexenta Systems, Inc.  All rights reserved.
 #
 
 #
 # The mpt_sas driver, as a pHCI driver, must specify the vHCI class it
 # belongs to(scsi_vhci).

@@ -47,5 +48,13 @@
 # To disable MPxIO on a controller whose parent is /pci@7c0/pci@0/pci@9
 # and the unit-address is "0" set:
 # name="mpt_sas" parent="/pci@7c0/pci@0/pci@9" unit-address="0" mpxio-disable="yes";
 #
 mpxio-disable="no";
+
+# mpt_sas can do I/O completion in helper threads, reducing the amount
+# of work done within interrupt context.
+#
+# mptsas_doneq_length_threshold_prop specifies the minimum number of
+# I/O completions pending to handle them in a helper thread, a value
+# of 0 causes all I/O completions to be passed to the helper threads.
+mptsas_doneq_length_threshold_prop=0;