PROBE::IOBLOCK.REQ(3stap)                        IO Scheduler and block IO Taps                        PROBE::IOBLOCK.REQ(3stap)



NAME
       probe::ioblock.request - Fires whenever making a generic block I/O request.

SYNOPSIS
       ioblock.request

VALUES
       None

DESCRIPTION
       name - name of the probe point devname - block device name ino - i-node number of the mapped file 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 hw_segments - number of segments after physical and DMA remapping
       hardware 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                                 August 2011                                 PROBE::IOBLOCK.REQ(3stap)