Merge branch 'upstream/wm8974' into for-2.6.33

[pandora-kernel.git] / Documentation / ABI / testing / sysfs-block

diff --git a/Documentation/ABI/testing/sysfs-block b/Documentation/ABI/testing/sysfs-block
index 44f52a4..cbbd3e0 100644 (file)
--- a/Documentation/ABI/testing/sysfs-block
+++ b/Documentation/ABI/testing/sysfs-block
@@ -60,3 +60,62 @@ Description:
                Indicates whether the block layer should automatically
                generate checksums for write requests bound for
                devices that support receiving integrity metadata.
                Indicates whether the block layer should automatically
                generate checksums for write requests bound for
                devices that support receiving integrity metadata.

+
+What:          /sys/block/<disk>/alignment_offset
+Date:          April 2009
+Contact:       Martin K. Petersen <martin.petersen@oracle.com>
+Description:
+               Storage devices may report a physical block size that is
+               bigger than the logical block size (for instance a drive
+               with 4KB physical sectors exposing 512-byte logical
+               blocks to the operating system).  This parameter
+               indicates how many bytes the beginning of the device is
+               offset from the disk's natural alignment.
+
+What:          /sys/block/<disk>/<partition>/alignment_offset
+Date:          April 2009
+Contact:       Martin K. Petersen <martin.petersen@oracle.com>
+Description:
+               Storage devices may report a physical block size that is
+               bigger than the logical block size (for instance a drive
+               with 4KB physical sectors exposing 512-byte logical
+               blocks to the operating system).  This parameter
+               indicates how many bytes the beginning of the partition
+               is offset from the disk's natural alignment.
+
+What:          /sys/block/<disk>/queue/logical_block_size
+Date:          May 2009
+Contact:       Martin K. Petersen <martin.petersen@oracle.com>
+Description:
+               This is the smallest unit the storage device can
+               address.  It is typically 512 bytes.
+
+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.
+
+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.
+
+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.