Messages in this thread Patch in this message | | | From | Liu Bo <> | Subject | [PATCH] Documentation: drop stale I/O barrier descriptions | Date | Wed, 28 Dec 2011 11:53:36 +0800 |
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Sorry for double mails, missing to cc LKML... ===
Since we've applied writeback_cache_control.txt and removed barrier.txt, drop the related descriptions in biodoc.txt.
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com> --- Documentation/block/biodoc.txt | 21 ++------------------- 1 files changed, 2 insertions(+), 19 deletions(-)
diff --git a/Documentation/block/biodoc.txt b/Documentation/block/biodoc.txt index e418dc0..2ce818f 100644 --- a/Documentation/block/biodoc.txt +++ b/Documentation/block/biodoc.txt @@ -48,8 +48,7 @@ Description of Contents: - Highmem I/O support - I/O scheduler modularization 1.2 Tuning based on high level requirements/capabilities - 1.2.1 I/O Barriers - 1.2.2 Request Priority/Latency + 1.2.1 Request Priority/Latency 1.3 Direct access/bypass to lower layers for diagnostics and special device operations 1.3.1 Pre-built commands @@ -261,23 +260,7 @@ unused). As far as user applications are concerned they would need an additional mechanism either via open flags or ioctls, or some other upper level mechanism to communicate such settings to block. -1.2.1 I/O Barriers - -There is a way to enforce strict ordering for i/os through barriers. -All requests before a barrier point must be serviced before the barrier -request and any other requests arriving after the barrier will not be -serviced until after the barrier has completed. This is useful for higher -level control on write ordering, e.g flushing a log of committed updates -to disk before the corresponding updates themselves. - -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. For more details regarding I/O barriers, please read barrier.txt -in this directory. - -1.2.2 Request Priority/Latency +1.2.1 Request Priority/Latency Todo/Under discussion: Arjan's proposed request priority scheme allows higher levels some broad -- 1.6.5.2
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