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author | Jens Axboe <jaxboe@fusionio.com> | 2010-06-09 08:42:09 (GMT) |
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committer | Jens Axboe <jaxboe@fusionio.com> | 2010-08-07 16:13:00 (GMT) |
commit | e2e1a148bc45855816ae6b4692ce29d0020fa22e (patch) | |
tree | fd5ec8a580d4333b471acfe50f6f92b4cc880087 /block/blk-core.c | |
parent | 841fdffdd382722d33579a6aa1487e8a4e526dbd (diff) | |
download | linux-fsl-qoriq-e2e1a148bc45855816ae6b4692ce29d0020fa22e.tar.xz |
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>
Diffstat (limited to 'block/blk-core.c')
-rw-r--r-- | block/blk-core.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index f0640d7..b4131d2 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -2111,7 +2111,8 @@ static bool blk_update_bidi_request(struct request *rq, int error, blk_update_request(rq->next_rq, error, bidi_bytes)) return true; - add_disk_randomness(rq->rq_disk); + if (blk_queue_add_random(rq->q)) + add_disk_randomness(rq->rq_disk); return false; } |