tree fd5ec8a580d4333b471acfe50f6f92b4cc880087
parent 841fdffdd382722d33579a6aa1487e8a4e526dbd
author Jens Axboe <jaxboe@fusionio.com> 1276072929 +0200
committer Jens Axboe <jaxboe@fusionio.com> 1281197580 +0200

block: add sysfs knob for turning off disk entropy contributions

There are two reasons for doing this:

- On SSD disks, the completion times aren't as random as they
  are for rotational drives. So it's questionable whether they
  should contribute to the random pool in the first place.

- Calling add_disk_randomness() has a lot of overhead.

This adds /sys/block/<dev>/queue/add_random that will allow you to
switch off on a per-device basis. The default setting is on, so there
should be no functional changes from this patch.

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>