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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.

SYNOPSIS

ioblock_trace.bounce

VALUES

rw
binary trace for read/write request
idx
offset into the bio vector array phys_segments - number of segments in this bio after physical address coalescing is performed.
ino
i-node number of the mapped file
q
request queue on which this bio was queued.
bdev
target block device
bytes_done
number of bytes transferred
bdev_contains
points to the device object which contains the partition (when bio structure represents a partition)
devname
device for which a buffer bounce was needed.
size
total size in bytes
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
sector
beginning sector for the entire bio
p_start_sect
points to the start sector of the partition structure of the device
name
name of the probe point
vcnt
bio vector count which represents number of array element (page, offset, length) which makes up this I/O request

CONTEXT

The process creating a block IO request.

SEE ALSO0

tapset::ioblock(3stap)
March 2016 SystemTap Tapset Reference