----- Original Message -----
From: "Justin T. Gibbs" <gi...@scsiguy.com>
On Jun 4, 2013, at 3:47, Steven Hartland <s...@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.
In theory I'd agree but in practice this was not the case with bioq
becoming a noticable bottleneck for SSD based machines, hence this change.
The sysctl's still allow this to be configured :)
Regards
Steve
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