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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>
authored by
Namjae Jeon
and committed by
Jens Axboe
4004e90c
2792d871
+64
+64
Documentation/block/queue-sysfs.txt
+64
Documentation/block/queue-sysfs.txt
···
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Files denoted with a RO postfix are readonly and the RW postfix means
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read-write.
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+
add_random (RW)
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----------------
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This file allows to trun off the disk entropy contribution. Default
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value of this file is '1'(on).
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discard_granularity (RO)
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-----------------------
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This shows the size of internal allocation of the device in bytes, if
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reported by the device. A value of '0' means device does not support
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the discard functionality.
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discard_max_bytes (RO)
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----------------------
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Devices that support discard functionality may have internal limits on
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the number of bytes that can be trimmed or unmapped in a single operation.
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The discard_max_bytes parameter is set by the device driver to the maximum
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number of bytes that can be discarded in a single operation. Discard
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requests issued to the device must not exceed this limit. A discard_max_bytes
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value of 0 means that the device does not support discard functionality.
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discard_zeroes_data (RO)
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------------------------
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When read, this file will show if the discarded block are zeroed by the
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device or not. If its value is '1' the blocks are zeroed otherwise not.
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hw_sector_size (RO)
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-------------------
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This is the hardware sector size of the device, in bytes.
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iostats (RW)
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-------------
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This file is used to control (on/off) the iostats accounting of the
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disk.
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+
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logical_block_size (RO)
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-----------------------
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This is the logcal block size of the device, in bytes.
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max_hw_sectors_kb (RO)
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----------------------
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This is the maximum number of kilobytes supported in a single data transfer.
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max_integrity_segments (RO)
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---------------------------
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When read, this file shows the max limit of integrity segments as
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set by block layer which a hardware controller can handle.
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max_sectors_kb (RW)
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-------------------
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This is the maximum number of kilobytes that the block layer will allow
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for a filesystem request. Must be smaller than or equal to the maximum
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size allowed by the hardware.
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max_segments (RO)
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-----------------
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Maximum number of segments of the device.
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max_segment_size (RO)
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---------------------
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Maximum segment size of the device.
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minimum_io_size (RO)
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--------------------
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This is the smallest preferred io size reported by the device.
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nomerges (RW)
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-------------
···
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each request queue may have upto N request pools, each independently
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regulated by nr_requests.
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optimal_io_size (RO)
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--------------------
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This is the optimal io size reported by the device.
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physical_block_size (RO)
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------------------------
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This is the physical block size of device, in bytes.
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read_ahead_kb (RW)
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------------------
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Maximum number of kilobytes to read-ahead for filesystems on this block
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device.
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rotational (RW)
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---------------
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This file is used to stat if the device is of rotational type or
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non-rotational type.
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rq_affinity (RW)
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----------------