BLK_LIMITS_IO_OPT(9) Block Devices BLK_LIMITS_IO_OPT(9)NAME
blk_limits_io_opt - set optimal request size for a device
SYNOPSIS
void blk_limits_io_opt(struct queue_limits * limits, unsigned int opt);
ARGUMENTS
limits
the queue limits
opt
smallest I/O size in bytes
DESCRIPTION
Storage devices may report an optimal I/O size, which is the device's preferred unit for sustained I/O. This is rarely reported for disk
drives. For RAID arrays it is usually the stripe width or the internal track size. A properly aligned multiple of optimal_io_size is the
preferred request size for workloads where sustained throughput is desired.
COPYRIGHT Kernel Hackers Manual 3.10 June 2014 BLK_LIMITS_IO_OPT(9)
Check Out this Related Man Page
BLOCKDEV(8) System Administration BLOCKDEV(8)NAME
blockdev - call block device ioctls from the command line
SYNOPSIS
blockdev [-q] [-v] command [command...] device [device...]
blockdev --report [device...]
DESCRIPTION
The utility blockdev allows one to call block device ioctls from the command line.
OPTIONS -V Print version and exit.
-q Be quiet.
-v Be verbose.
--report
Print a report for the specified device. It is possible to give multiple devices. If none is given, all devices which appear in
/proc/partitions are shown. Note that the partition StartSec is in 512-byte sectors.
COMMANDS
It is possible to give multiple devices and multiple commands.
--flushbufs
Flush buffers.
--getalignoff
Get alignment offset.
--getbsz
Print blocksize in bytes.
--getdiscardzeroes
Get discard zeroes support status.
--getfra
Get filesystem readahead in 512-byte sectors.
--getiomin
Get minimum I/O size.
--getioopt
Get optimal I/O size.
--getmaxsect
Get max sectors per request
--getpbsz
Get physical block (sector) size.
--getra
Print readahead (in 512-byte sectors).
--getro
Get read-only. Print 1 if the device is read-only, 0 otherwise.
--getsize64
Print device size in bytes.
--getsize
Print device size (32-bit!) in sectors. Deprecated in favor of the --getsz option.
--getss
Print sectorsize in bytes - usually 512.
--getsz
Get size in 512-byte sectors.
--rereadpt
Reread partition table
--setbsz bytes
Set blocksize. Note that the block size is specific to the current file descriptor opening the block device, so the change of block
size only persists for as long as blockdev has the device open, and is lost once blockdev exits.
--setfra sectors
Set filesystem readahead (same like --setra on 2.6 kernels).
--setra sectors
Set readahead (in 512-byte sectors).
--setro
Set read-only.
--setrw
Set read-write.
AUTHOR
blockdev was written by Andries E. Brouwer and rewritten by Karel Zak.
AVAILABILITY
The blockdev command is part of the util-linux package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.
util-linux August 2010 BLOCKDEV(8)
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