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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

bdev
target block device

name

name of the probe point

devname

device for which a buffer bounce was needed.

vcnt

bio vector count which represents number of array element (page, offset, length) which makes up this I/O request

opf

operations and flags

ino

i-node number of the mapped file

bytes_done

number of bytes transferred

bdev_contains

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

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

rw

binary trace for read/write request

p_start_sect

points to the start sector of the partition structure of the device

idx

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

sector

beginning sector for the entire bio

CONTEXT

The process creating a block IO request.

SEE ALSO0

tapset::ioblock(3stap)
May 2021 SystemTap Tapset Reference