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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

bdev
target block device

bytes_done

number of bytes transferred

ino

i-node number of the mapped file

idx

offset into the bio vector array phys_segments - number of segments in this bio after physical address coalescing is performed.

rw

binary trace for read/write request

q

request queue on which this bio was queued.

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

size

total size in bytes

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 make up this I/O request

sector

beginning sector for the entire bio

devname

block device name

bdev_contains

points to the device object which contains the partition (when bio structure represents a partition)

CONTEXT

The process makes block I/O request

SEE ALSO0

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