TRACE_BLOCK_BIO_BOUN(9) Block IO TRACE_BLOCK_BIO_BOUN(9)NAME
trace_block_bio_bounce - used bounce buffer when processing block operation
void trace_block_bio_bounce(struct request_queue * q, struct bio * bio);
queue holding the block operation
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.
Jason Baron <firstname.lastname@example.org>
William Cohen <email@example.com>
COPYRIGHT Kernel Hackers Manual 3.10 June 2014 TRACE_BLOCK_BIO_BOUN(9)
Check Out this Related Man Page
PROBE::IOBLOCK_TRACE(3stap) IO Scheduler and block IO Taps PROBE::IOBLOCK_TRACE(3stap)NAME
probe::ioblock_trace.bounce - Fires whenever a buffer bounce is needed for at least one page of a block IO request.
name - name of the probe point q - request queue on which this bio was queued. devname - device for which a buffer bounce was needed. 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 makes 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
The process creating a block IO request.
SystemTap Tapset Reference June 2014 PROBE::IOBLOCK_TRACE(3stap)
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