svn commit: r251372 - in stable/9/sys/cam: ata scsi

[Justin T. Gibbs]

On Jun 4, 2013, at 3:47, Steven Hartland <smh at FreeBSD.org> wrote:

> Author: smh
> Date: Tue Jun  4 10:47:44 2013
> New Revision: 251372
> URL: http://svnweb.freebsd.org/changeset/base/251372
> 
> Log:
>  Enhanced BIO_DELETE support for CAM SCSI to add ATA_TRIM support.
> 
>  Disable CAM BIO queue sorting for non-rotating media by default.

Using the elevator makes perfect sense even for random access devices when operations can be merged. Even SSDs have fixed, per-command overheads and merging writes may help prevent fragmentation.  On drivers that support unmapped I/O, merging should be fairly cheap.

It would be an interesting performance experiment.
> 

--
Justin