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