blk_queue_io_opt(9) [centos man page]

BLK_QUEUE_IO_OPT(9)						   Block Devices					       BLK_QUEUE_IO_OPT(9)

NAME

       blk_queue_io_opt - set optimal request size for the queue

SYNOPSIS

       void blk_queue_io_opt(struct request_queue * q, unsigned int opt);

ARGUMENTS

       q
	   the request queue for the device

       opt
	   optimal request 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_QUEUE_IO_OPT(9)

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.

       --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)