[BLOCK] I/O barrier documentation update

Update documentation to match new barrier implementation.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jens Axboe <axboe@suse.de>
This commit is contained in:
Tejun Heo 2006-01-06 09:58:37 +01:00 committed by Jens Axboe
parent 3e087b5754
commit ff5b8cf149
1 changed files with 2 additions and 8 deletions

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@ -263,14 +263,8 @@ A flag in the bio structure, BIO_BARRIER is used to identify a barrier i/o.
The generic i/o scheduler would make sure that it places the barrier request and
all other requests coming after it after all the previous requests in the
queue. Barriers may be implemented in different ways depending on the
driver. A SCSI driver for example could make use of ordered tags to
preserve the necessary ordering with a lower impact on throughput. For IDE
this might be two sync cache flush: a pre and post flush when encountering
a barrier write.
There is a provision for queues to indicate what kind of barriers they
can provide. This is as of yet unmerged, details will be added here once it
is in the kernel.
driver. For more details regarding I/O barriers, please read barrier.txt
in this directory.
1.2.2 Request Priority/Latency