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Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-block

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* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
  Make SCSI SG v4 driver enabled by default and remove EXPERIMENTAL dependency, since udev depends on BSG
  block: Update topology documentation
  block: Stack optimal I/O size
  block: Add a wrapper for setting minimum request size without a queue
  block: Make blk_queue_stack_limits use the new stacking interface
This commit is contained in:
Linus Torvalds
2009-08-04 15:39:16 -07:00
parent ae83060026 14d9fa3525
commit 2cf812d732
4 changed files with 78 additions and 50 deletions
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37
Documentation/ABI/testing/sysfs-block
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@@ -94,28 +94,37 @@ What: /sys/block/<disk>/queue/physical_block_size
Date: May 2009
Contact: Martin K. Petersen <martin.petersen@oracle.com>
Description:
This is the smallest unit the storage device can write
without resorting to read-modify-write operation. It is
usually the same as the logical block size but may be
bigger. One example is SATA drives with 4KB sectors
that expose a 512-byte logical block size to the
operating system.
This is the smallest unit a physical storage device can
write atomically. It is usually the same as the logical
block size but may be bigger. One example is SATA
drives with 4KB sectors that expose a 512-byte logical
block size to the operating system. For stacked block
devices the physical_block_size variable contains the
maximum physical_block_size of the component devices.
What: /sys/block/<disk>/queue/minimum_io_size
Date: April 2009
Contact: Martin K. Petersen <martin.petersen@oracle.com>
Description:
Storage devices may report a preferred minimum I/O size,
which is the smallest request the device can perform
without incurring a read-modify-write penalty. For disk
drives this is often the physical block size. For RAID
arrays it is often the stripe chunk size.
Storage devices may report a granularity or preferred
minimum I/O size which is the smallest request the
device can perform without incurring a performance
penalty. For disk drives this is often the physical
block size. For RAID arrays it is often the stripe
chunk size. A properly aligned multiple of
minimum_io_size is the preferred request size for
workloads where a high number of I/O operations is
desired.
What: /sys/block/<disk>/queue/optimal_io_size
Date: April 2009
Contact: Martin K. Petersen <martin.petersen@oracle.com>
Description:
Storage devices may report an optimal I/O size, which is
the device's preferred unit of receiving I/O. This is
rarely reported for disk drives. For RAID devices it is
usually the stripe width or the internal block size.
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. If no optimal I/O size is
reported this file contains 0.