Merge git://git.infradead.org/battery-2.6

[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.
+
+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.