Add DocBook documentation for the block tracepoints.
This patch adds a simple description of the various block tracepoints available in the kernel. Signed-off-by: William Cohen <wcohen@redhat.com> Acked-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
William Cohen
Jens Axboe
parent
c2282adbde
commit
881245dcff
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@ -16,6 +16,15 @@
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</address>
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</affiliation>
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</author>
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<author>
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<firstname>William</firstname>
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<surname>Cohen</surname>
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<affiliation>
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<address>
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<email>wcohen@redhat.com</email>
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</address>
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</affiliation>
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</author>
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</authorgroup>
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<legalnotice>
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@ -91,4 +100,8 @@
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!Iinclude/trace/events/signal.h
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</chapter>
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<chapter id="block">
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<title>Block IO</title>
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!Iinclude/trace/events/block.h
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</chapter>
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</book>
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@ -40,6 +40,16 @@ DECLARE_EVENT_CLASS(block_rq_with_error,
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__entry->nr_sector, __entry->errors)
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);
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/**
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* block_rq_abort - abort block operation request
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* @q: queue containing the block operation request
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* @rq: block IO operation request
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*
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* Called immediately after pending block IO operation request @rq in
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* queue @q is aborted. The fields in the operation request @rq
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* can be examined to determine which device and sectors the pending
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* operation would access.
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*/
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DEFINE_EVENT(block_rq_with_error, block_rq_abort,
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TP_PROTO(struct request_queue *q, struct request *rq),
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@ -47,6 +57,15 @@ DEFINE_EVENT(block_rq_with_error, block_rq_abort,
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TP_ARGS(q, rq)
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);
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/**
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* block_rq_requeue - place block IO request back on a queue
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* @q: queue holding operation
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* @rq: block IO operation request
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*
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* The block operation request @rq is being placed back into queue
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* @q. For some reason the request was not completed and needs to be
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* put back in the queue.
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*/
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DEFINE_EVENT(block_rq_with_error, block_rq_requeue,
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TP_PROTO(struct request_queue *q, struct request *rq),
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@ -54,6 +73,17 @@ DEFINE_EVENT(block_rq_with_error, block_rq_requeue,
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TP_ARGS(q, rq)
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);
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/**
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* block_rq_complete - block IO operation completed by device driver
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* @q: queue containing the block operation request
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* @rq: block operations request
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*
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* The block_rq_complete tracepoint event indicates that some portion
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* of operation request has been completed by the device driver. If
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* the @rq->bio is %NULL, then there is absolutely no additional work to
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* do for the request. If @rq->bio is non-NULL then there is
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* additional work required to complete the request.
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*/
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DEFINE_EVENT(block_rq_with_error, block_rq_complete,
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TP_PROTO(struct request_queue *q, struct request *rq),
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@ -95,6 +125,16 @@ DECLARE_EVENT_CLASS(block_rq,
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__entry->nr_sector, __entry->comm)
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);
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/**
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* block_rq_insert - insert block operation request into queue
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* @q: target queue
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* @rq: block IO operation request
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*
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* Called immediately before block operation request @rq is inserted
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* into queue @q. The fields in the operation request @rq struct can
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* be examined to determine which device and sectors the pending
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* operation would access.
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*/
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DEFINE_EVENT(block_rq, block_rq_insert,
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TP_PROTO(struct request_queue *q, struct request *rq),
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@ -102,6 +142,14 @@ DEFINE_EVENT(block_rq, block_rq_insert,
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TP_ARGS(q, rq)
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);
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/**
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* block_rq_issue - issue pending block IO request operation to device driver
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* @q: queue holding operation
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* @rq: block IO operation operation request
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*
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* Called when block operation request @rq from queue @q is sent to a
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* device driver for processing.
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*/
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DEFINE_EVENT(block_rq, block_rq_issue,
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TP_PROTO(struct request_queue *q, struct request *rq),
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@ -109,6 +157,17 @@ DEFINE_EVENT(block_rq, block_rq_issue,
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TP_ARGS(q, rq)
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);
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/**
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* block_bio_bounce - used bounce buffer when processing block operation
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* @q: queue holding the block operation
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* @bio: block operation
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*
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* A bounce buffer was used to handle the block operation @bio in @q.
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* This occurs when hardware limitations prevent a direct transfer of
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* data between the @bio data memory area and the IO device. Use of a
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* bounce buffer requires extra copying of data and decreases
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* performance.
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*/
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TRACE_EVENT(block_bio_bounce,
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TP_PROTO(struct request_queue *q, struct bio *bio),
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@ -138,6 +197,14 @@ TRACE_EVENT(block_bio_bounce,
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__entry->nr_sector, __entry->comm)
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);
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/**
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* block_bio_complete - completed all work on the block operation
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* @q: queue holding the block operation
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* @bio: block operation completed
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*
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* This tracepoint indicates there is no further work to do on this
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* block IO operation @bio.
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*/
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TRACE_EVENT(block_bio_complete,
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TP_PROTO(struct request_queue *q, struct bio *bio),
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@ -193,6 +260,14 @@ DECLARE_EVENT_CLASS(block_bio,
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__entry->nr_sector, __entry->comm)
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);
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/**
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* block_bio_backmerge - merging block operation to the end of an existing operation
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* @q: queue holding operation
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* @bio: new block operation to merge
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*
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* Merging block request @bio to the end of an existing block request
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* in queue @q.
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*/
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DEFINE_EVENT(block_bio, block_bio_backmerge,
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TP_PROTO(struct request_queue *q, struct bio *bio),
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@ -200,6 +275,14 @@ DEFINE_EVENT(block_bio, block_bio_backmerge,
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TP_ARGS(q, bio)
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);
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/**
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* block_bio_frontmerge - merging block operation to the beginning of an existing operation
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* @q: queue holding operation
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* @bio: new block operation to merge
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*
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* Merging block IO operation @bio to the beginning of an existing block
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* operation in queue @q.
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*/
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DEFINE_EVENT(block_bio, block_bio_frontmerge,
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TP_PROTO(struct request_queue *q, struct bio *bio),
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@ -207,6 +290,13 @@ DEFINE_EVENT(block_bio, block_bio_frontmerge,
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TP_ARGS(q, bio)
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);
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/**
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* block_bio_queue - putting new block IO operation in queue
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* @q: queue holding operation
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* @bio: new block operation
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*
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* About to place the block IO operation @bio into queue @q.
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*/
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DEFINE_EVENT(block_bio, block_bio_queue,
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TP_PROTO(struct request_queue *q, struct bio *bio),
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@ -243,6 +333,15 @@ DECLARE_EVENT_CLASS(block_get_rq,
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__entry->nr_sector, __entry->comm)
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);
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/**
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* block_getrq - get a free request entry in queue for block IO operations
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* @q: queue for operations
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* @bio: pending block IO operation
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* @rw: low bit indicates a read (%0) or a write (%1)
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*
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* A request struct for queue @q has been allocated to handle the
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* block IO operation @bio.
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*/
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DEFINE_EVENT(block_get_rq, block_getrq,
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TP_PROTO(struct request_queue *q, struct bio *bio, int rw),
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@ -250,6 +349,17 @@ DEFINE_EVENT(block_get_rq, block_getrq,
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TP_ARGS(q, bio, rw)
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);
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/**
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* block_sleeprq - waiting to get a free request entry in queue for block IO operation
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* @q: queue for operation
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* @bio: pending block IO operation
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* @rw: low bit indicates a read (%0) or a write (%1)
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*
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* In the case where a request struct cannot be provided for queue @q
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* the process needs to wait for an request struct to become
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* available. This tracepoint event is generated each time the
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* process goes to sleep waiting for request struct become available.
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*/
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DEFINE_EVENT(block_get_rq, block_sleeprq,
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TP_PROTO(struct request_queue *q, struct bio *bio, int rw),
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@ -257,6 +367,14 @@ DEFINE_EVENT(block_get_rq, block_sleeprq,
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TP_ARGS(q, bio, rw)
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);
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/**
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* block_plug - keep operations requests in request queue
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* @q: request queue to plug
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*
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* Plug the request queue @q. Do not allow block operation requests
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* to be sent to the device driver. Instead, accumulate requests in
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* the queue to improve throughput performance of the block device.
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*/
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TRACE_EVENT(block_plug,
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TP_PROTO(struct request_queue *q),
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@ -293,6 +411,13 @@ DECLARE_EVENT_CLASS(block_unplug,
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TP_printk("[%s] %d", __entry->comm, __entry->nr_rq)
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);
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/**
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* block_unplug_timer - timed release of operations requests in queue to device driver
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* @q: request queue to unplug
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*
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* Unplug the request queue @q because a timer expired and allow block
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* operation requests to be sent to the device driver.
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*/
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DEFINE_EVENT(block_unplug, block_unplug_timer,
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TP_PROTO(struct request_queue *q),
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@ -300,6 +425,13 @@ DEFINE_EVENT(block_unplug, block_unplug_timer,
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TP_ARGS(q)
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);
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/**
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* block_unplug_io - release of operations requests in request queue
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* @q: request queue to unplug
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*
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* Unplug request queue @q because device driver is scheduled to work
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* on elements in the request queue.
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*/
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DEFINE_EVENT(block_unplug, block_unplug_io,
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TP_PROTO(struct request_queue *q),
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@ -307,6 +439,17 @@ DEFINE_EVENT(block_unplug, block_unplug_io,
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TP_ARGS(q)
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);
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/**
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* block_split - split a single bio struct into two bio structs
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* @q: queue containing the bio
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* @bio: block operation being split
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* @new_sector: The starting sector for the new bio
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*
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* The bio request @bio in request queue @q needs to be split into two
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* bio requests. The newly created @bio request starts at
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* @new_sector. This split may be required due to hardware limitation
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* such as operation crossing device boundaries in a RAID system.
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*/
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TRACE_EVENT(block_split,
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TP_PROTO(struct request_queue *q, struct bio *bio,
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@ -337,6 +480,16 @@ TRACE_EVENT(block_split,
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__entry->comm)
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);
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/**
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* block_remap - map request for a partition to the raw device
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* @q: queue holding the operation
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* @bio: revised operation
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* @dev: device for the operation
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* @from: original sector for the operation
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*
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* An operation for a partition on a block device has been mapped to the
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* raw block device.
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*/
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TRACE_EVENT(block_remap,
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TP_PROTO(struct request_queue *q, struct bio *bio, dev_t dev,
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@ -370,6 +523,17 @@ TRACE_EVENT(block_remap,
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(unsigned long long)__entry->old_sector)
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);
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/**
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* block_rq_remap - map request for a block operation request
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* @q: queue holding the operation
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* @rq: block IO operation request
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* @dev: device for the operation
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* @from: original sector for the operation
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*
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* The block operation request @rq in @q has been remapped. The block
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* operation request @rq holds the current information and @from hold
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* the original sector.
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*/
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TRACE_EVENT(block_rq_remap,
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TP_PROTO(struct request_queue *q, struct request *rq, dev_t dev,
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