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[PATCH] block: document io scheduler allow_merge_fn hook 

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Jens Axboe 2006-12-20 11:06:15 +01:00
parent da77526502
commit 126ec9a676
1 changed files with 7 additions and 0 deletions
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7
Documentation/block/biodoc.txt
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@ -946,6 +946,13 @@ elevator_merged_fn called when a request in the scheduler has been
scheduler for example, to reposition the request scheduler for example, to reposition the request
if its sorting order has changed. if its sorting order has changed.
elevator_allow_merge_fn called whenever the block layer determines
that a bio can be merged into an existing
request safely. The io scheduler may still
want to stop a merge at this point if it
results in some sort of conflict internally,
this hook allows it to do that.
elevator_dispatch_fn fills the dispatch queue with ready requests. elevator_dispatch_fn fills the dispatch queue with ready requests.
I/O schedulers are free to postpone requests by I/O schedulers are free to postpone requests by
not filling the dispatch queue unless @force not filling the dispatch queue unless @force