[illumos-Developer] webrev: 975 disable disksort for SSDs

[Garrett D'Amore]

This is a trivial webrev.  I've tested it, but not gathered any
quantifiable data yet.  (If someone feels that I absolutely must have
such data to proceed, let me know.  In this particular case, I think the
change is relatively obvious and low risk... I've a colleague working to
get actual numbers but it might take some time.)

Webrev is here:  http://mexico.purplecow.org/gdamore/webrev/nodisksort/

As someone else has pointed out, yes, it would probably make sense to do
this for RAID arrays too (HW raid), but its harder to detect those, and
the situation isn't as clearly obviously a win as it is with solid state
storage.

There's a very short timer on this.

	- Garrett