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-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 6518a55273e..e54ac1d5340 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.
9Files denoted with a RO postfix are readonly and the RW postfix means 9Files denoted with a RO postfix are readonly and the RW postfix means
10read-write. 10read-write.
11 11
12add_random (RW)
13----------------
14This file allows to trun off the disk entropy contribution. Default
15value of this file is '1'(on).
16
17discard_granularity (RO)
18-----------------------
19This shows the size of internal allocation of the device in bytes, if
20reported by the device. A value of '0' means device does not support
21the discard functionality.
22
23discard_max_bytes (RO)
24----------------------
25Devices that support discard functionality may have internal limits on
26the number of bytes that can be trimmed or unmapped in a single operation.
27The discard_max_bytes parameter is set by the device driver to the maximum
28number of bytes that can be discarded in a single operation. Discard
29requests issued to the device must not exceed this limit. A discard_max_bytes
30value of 0 means that the device does not support discard functionality.
31
32discard_zeroes_data (RO)
33------------------------
34When read, this file will show if the discarded block are zeroed by the
35device or not. If its value is '1' the blocks are zeroed otherwise not.
36
12hw_sector_size (RO) 37hw_sector_size (RO)
13------------------- 38-------------------
14This is the hardware sector size of the device, in bytes. 39This is the hardware sector size of the device, in bytes.
15 40
41iostats (RW)
42-------------
43This file is used to control (on/off) the iostats accounting of the
44disk.
45
46logical_block_size (RO)
47-----------------------
48This is the logcal block size of the device, in bytes.
49
16max_hw_sectors_kb (RO) 50max_hw_sectors_kb (RO)
17---------------------- 51----------------------
18This is the maximum number of kilobytes supported in a single data transfer. 52This is the maximum number of kilobytes supported in a single data transfer.
19 53
54max_integrity_segments (RO)
55---------------------------
56When read, this file shows the max limit of integrity segments as
57set by block layer which a hardware controller can handle.
58
20max_sectors_kb (RW) 59max_sectors_kb (RW)
21------------------- 60-------------------
22This is the maximum number of kilobytes that the block layer will allow 61This is the maximum number of kilobytes that the block layer will allow
23for a filesystem request. Must be smaller than or equal to the maximum 62for a filesystem request. Must be smaller than or equal to the maximum
24size allowed by the hardware. 63size allowed by the hardware.
25 64
65max_segments (RO)
66-----------------
67Maximum number of segments of the device.
68
69max_segment_size (RO)
70---------------------
71Maximum segment size of the device.
72
73minimum_io_size (RO)
74--------------------
75This is the smallest preferred io size reported by the device.
76
26nomerges (RW) 77nomerges (RW)
27------------- 78-------------
28This enables the user to disable the lookup logic involved with IO 79This 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,
45each request queue may have upto N request pools, each independently 96each request queue may have upto N request pools, each independently
46regulated by nr_requests. 97regulated by nr_requests.
47 98
99optimal_io_size (RO)
100--------------------
101This is the optimal io size reported by the device.
102
103physical_block_size (RO)
104------------------------
105This is the physical block size of device, in bytes.
106
48read_ahead_kb (RW) 107read_ahead_kb (RW)
49------------------ 108------------------
50Maximum number of kilobytes to read-ahead for filesystems on this block 109Maximum number of kilobytes to read-ahead for filesystems on this block
51device. 110device.
52 111
112rotational (RW)
113---------------
114This file is used to stat if the device is of rotational type or
115non-rotational type.
116
53rq_affinity (RW) 117rq_affinity (RW)
54---------------- 118----------------
55If this option is '1', the block layer will migrate request completions to the 119If this option is '1', the block layer will migrate request completions to the