Mike Long <mike.long@analog.com> writes:
>This was all discussed a year ago.  The result was that the defaults
>for newfs(8) were changed to eliminate rotdelay (-d).  AFAIK, if
>rotdelay is zero, then disksort() becomes a NOP.

I took a look at disksort() and as far as I can tell rotdelay has no
effect on it. It sorts the requests according to cylinder and block
numbers. The fs_rotdelay field seems to be used in ffs_alloc.c where
blocks are allocated.

Christoph Badura <bad@flatlin.ka.sub.org> writes:
>Actually, no.  disksort() has no idea about the drive geometry.  It
>sorts the requests in increasing cylinder order and sorts within a
>cylinder in increasing block order.  This works for ZBR drives too.
>Since the driver tells disksort what cylinder a block lies in it could
>even report the correct cylinder for ZBR drives, if it could figure
>that out.

I have a feeling that some drives might lie about the number of heads
and number of cylinders when they construct the imaginary geometry. If
this geometry is used by the disksort(), it might hurt performance.