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authorNamjae Jeon <linkinjeon@gmail.com>2012-08-09 15:28:05 +0200
committerJens Axboe <axboe@kernel.dk>2012-08-09 15:28:05 +0200
commit4004e90cfa4488cf99798b1138183158b64f4a42 (patch)
tree4728cd987434ce7806259bc23b765442995a2b68 /Documentation/block
parent2792d8719393a518a847769d36a080ade4273e6b (diff)
downloadlinux-linaro-stable-4004e90cfa4488cf99798b1138183158b64f4a42.tar.gz
Documentation: update tunable options in block/cfq-iosched.txt
Update tunable options in block/cfq-iosched.txt. Signed-off-by: Namjae Jeon <linkinjeon@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'Documentation/block')
-rw-r--r--Documentation/block/queue-sysfs.txt64
1 files changed, 64 insertions, 0 deletions
diff --git a/Documentation/block/queue-sysfs.txt b/Documentation/block/queue-sysfs.txt
index 6518a55273e7..e54ac1d53403 100644
--- a/Documentation/block/queue-sysfs.txt
+++ b/Documentation/block/queue-sysfs.txt
@@ -9,20 +9,71 @@ These files are the ones found in the /sys/block/xxx/queue/ directory.
Files denoted with a RO postfix are readonly and the RW postfix means
read-write.
+add_random (RW)
+----------------
+This file allows to trun off the disk entropy contribution. Default
+value of this file is '1'(on).
+
+discard_granularity (RO)
+-----------------------
+This shows the size of internal allocation of the device in bytes, if
+reported by the device. A value of '0' means device does not support
+the discard functionality.
+
+discard_max_bytes (RO)
+----------------------
+Devices that support discard functionality may have internal limits on
+the number of bytes that can be trimmed or unmapped in a single operation.
+The discard_max_bytes parameter is set by the device driver to the maximum
+number of bytes that can be discarded in a single operation. Discard
+requests issued to the device must not exceed this limit. A discard_max_bytes
+value of 0 means that the device does not support discard functionality.
+
+discard_zeroes_data (RO)
+------------------------
+When read, this file will show if the discarded block are zeroed by the
+device or not. If its value is '1' the blocks are zeroed otherwise not.
+
hw_sector_size (RO)
-------------------
This is the hardware sector size of the device, in bytes.
+iostats (RW)
+-------------
+This file is used to control (on/off) the iostats accounting of the
+disk.
+
+logical_block_size (RO)
+-----------------------
+This is the logcal block size of the device, in bytes.
+
max_hw_sectors_kb (RO)
----------------------
This is the maximum number of kilobytes supported in a single data transfer.
+max_integrity_segments (RO)
+---------------------------
+When read, this file shows the max limit of integrity segments as
+set by block layer which a hardware controller can handle.
+
max_sectors_kb (RW)
-------------------
This is the maximum number of kilobytes that the block layer will allow
for a filesystem request. Must be smaller than or equal to the maximum
size allowed by the hardware.
+max_segments (RO)
+-----------------
+Maximum number of segments of the device.
+
+max_segment_size (RO)
+---------------------
+Maximum segment size of the device.
+
+minimum_io_size (RO)
+--------------------
+This is the smallest preferred io size reported by the device.
+
nomerges (RW)
-------------
This enables the user to disable the lookup logic involved with IO
@@ -45,11 +96,24 @@ per-block-cgroup request pool. IOW, if there are N block cgroups,
each request queue may have upto N request pools, each independently
regulated by nr_requests.
+optimal_io_size (RO)
+--------------------
+This is the optimal io size reported by the device.
+
+physical_block_size (RO)
+------------------------
+This is the physical block size of device, in bytes.
+
read_ahead_kb (RW)
------------------
Maximum number of kilobytes to read-ahead for filesystems on this block
device.
+rotational (RW)
+---------------
+This file is used to stat if the device is of rotational type or
+non-rotational type.
+
rq_affinity (RW)
----------------
If this option is '1', the block layer will migrate request completions to the