trace_block_bio_bounce(9) [centos man page]

TRACE_BLOCK_BIO_BOUN(9) 					     Block IO						   TRACE_BLOCK_BIO_BOUN(9)

NAME

       trace_block_bio_bounce - used bounce buffer when processing block operation

SYNOPSIS

       void trace_block_bio_bounce(struct request_queue * q, struct bio * bio);

ARGUMENTS

       q
	   queue holding the block operation

       bio
	   block operation

DESCRIPTION

       A bounce buffer was used to handle the block operation bio in q. This occurs when hardware limitations prevent a direct transfer of data
       between the bio data memory area and the IO device. Use of a bounce buffer requires extra copying of data and decreases performance.

AUTHORS

       Jason Baron <jbaron@redhat.com>
	   Author.

       William Cohen <wcohen@redhat.com>
	   Author.

COPYRIGHT

Kernel Hackers Manual 3.10					     June 2014						   TRACE_BLOCK_BIO_BOUN(9)

PROBE::IOBLOCK_TRACE(3stap)				  IO Scheduler and block IO Taps			       PROBE::IOBLOCK_TRACE(3stap)

NAME

       probe::ioblock_trace.request - Fires just as a generic block I/O request is created for a bio.

SYNOPSIS

       ioblock_trace.request

VALUES

       None

DESCRIPTION

       name - name of the probe point q - request queue on which this bio was queued.  devname - block device name ino - i-node number of the
       mapped file bytes_done - number of bytes transferred sector - beginning sector for the entire bio flags - see below BIO_UPTODATE 0 ok after
       I/O completion BIO_RW_BLOCK 1 RW_AHEAD set, and read/write would block BIO_EOF 2 out-out-bounds error BIO_SEG_VALID 3 nr_hw_seg valid
       BIO_CLONED 4 doesn't own data BIO_BOUNCED 5 bio is a bounce bio BIO_USER_MAPPED 6 contains user pages BIO_EOPNOTSUPP 7 not supported

       rw - binary trace for read/write request vcnt - bio vector count which represents number of array element (page, offset, length) which make
       up this I/O request idx - offset into the bio vector array phys_segments - number of segments in this bio after physical address coalescing
       is performed.  size - total size in bytes bdev - target block device bdev_contains - points to the device object which contains the
       partition (when bio structure represents a partition) p_start_sect - points to the start sector of the partition structure of the device

CONTEXT

       The process makes block I/O request

SystemTap Tapset Reference					     June 2014					       PROBE::IOBLOCK_TRACE(3stap)