TRACE_BLOCK_SLEEPRQ(9) Block IO TRACE_BLOCK_SLEEPRQ(9)NAME
trace_block_sleeprq - waiting to get a free request entry in queue for block IO operation
void trace_block_sleeprq(struct request_queue * q, struct bio * bio, int rw);
queue for operation
pending block IO operation
low bit indicates a read (0) or a write (1)
In the case where a request struct cannot be provided for queue q the process needs to wait for an request struct to become available. This
tracepoint event is generated each time the process goes to sleep waiting for request struct become available.
Jason Baron <email@example.com>
William Cohen <firstname.lastname@example.org>
COPYRIGHT Kernel Hackers Manual 3.10 June 2014 TRACE_BLOCK_SLEEPRQ(9)
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BLK_INIT_QUEUE(9) Block Devices BLK_INIT_QUEUE(9)NAME
blk_init_queue - prepare a request queue for use with a block device
struct request_queue * blk_init_queue(request_fn_proc * rfn, spinlock_t * lock);
The function to be called to process requests that have been placed on the queue.
Request queue spin lock
If a block device wishes to use the standard request handling procedures, which sorts requests and coalesces adjacent requests, then it
must call blk_init_queue. The function rfn will be called when there are requests on the queue that need to be processed. If the device
supports plugging, then rfn may not be called immediately when requests are available on the queue, but may be called at some time later
instead. Plugged queues are generally unplugged when a buffer belonging to one of the requests on the queue is needed, or due to memory
rfn is not required, or even expected, to remove all requests off the queue, but only as many as it can handle at a time. If it does leave
requests on the queue, it is responsible for arranging that the requests get dealt with eventually.
The queue spin lock must be held while manipulating the requests on the request queue; this lock will be taken also from interrupt context,
so irq disabling is needed for it.
Function returns a pointer to the initialized request queue, or NULL if it didn't succeed.
blk_init_queue must be paired with a blk_cleanup_queue call when the block device is deactivated (such as at module unload).
COPYRIGHT Kernel Hackers Manual 2.6. July 2010 BLK_INIT_QUEUE(9)
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