| /Documentation/driver-api/md/ |
| D | raid5-cache.rst | 7 caches data to the RAID disks. The cache can be in write-through (supported
8 since 4.4) or write-back mode (supported since 4.10). mdadm (supported since
9 3.4) has a new option '--write-journal' to create array with cache. Please
11 in write-through mode. A user can switch it to write-back mode by::
13 echo "write-back" > /sys/block/md0/md/journal_mode
15 And switch it back to write-through mode by::
17 echo "write-through" > /sys/block/md0/md/journal_mode
22 write-through mode
25 This mode mainly fixes the 'write hole' issue. For RAID 4/5/6 array, an unclean
27 and parity don't match. The reason is that a stripe write involves several RAID
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| D | raid5-ppl.rst | 11 that have not been touched by a write request during the unclean shutdown can
12 be incorrect. Such condition is known as the RAID5 Write Hole. Because of
15 Partial parity for a write operation is the XOR of stripe data chunks not
16 modified by this write. It is just enough data needed for recovering from the
17 write hole. XORing partial parity with the modified chunks produces parity for
18 the stripe, consistent with its state before the write operation, regardless of
23 the array. Because of this, using write-intent bitmap and PPL together is not
26 When handling a write request PPL writes partial parity before new data and
29 stripe. It does not require a dedicated journaling drive. Write performance is
34 Unlike raid5-cache, the other solution in md for closing the write hole, PPL is
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| /Documentation/ABI/testing/ |
| D | sysfs-class-bdi | 32 (read-write)
38 total write-back cache that relates to its current average
42 percentage of the write-back cache to a particular device.
45 (read-write)
52 total write-back cache that relates to its current average
56 of the write-back cache to a particular device. The value is
60 (read-write)
67 given percentage of the write-back cache. This is useful in
69 most of the write-back cache. For example in case of an NFS
73 (read-write)
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| D | sysfs-driver-xdata | 1 What: /sys/class/misc/drivers/dw-xdata-pcie.<device>/write
6 will create write TLPs frames - from the Root Complex to the
10 Write y/1/on to enable, n/0/off to disable
13 echo 1 > /sys/class/misc/dw-xdata-pcie.<device>/write
15 echo 0 > /sys/class/misc/dw-xdata-pcie.<device>/write
21 cat /sys/class/misc/dw-xdata-pcie.<device>/write
24 The file is read and write.
35 Write y/1/on to enable, n/0/off to disable
49 The file is read and write.
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| D | sysfs-block-zram | 5 The disksize file is read-write and specifies the disk size
21 The reset file is write-only and allows resetting the
29 The max_comp_streams file is read-write and specifies the
37 The comp_algorithm file is read-write and lets to show
45 The mem_used_max file is write-only and is used to reset
47 compressed data. For resetting the value, you should write
55 The mem_limit file is write-only and specifies the maximum
64 The compact file is write-only and trigger compaction for
98 The backing_dev file is read-write and set up backing
99 device for zram to write incompressible pages.
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| D | configfs-spear-pcie-gadget | 24 inta write 1 to assert INTA and 0 to de-assert.
25 send_msi write MSI vector to be sent.
26 vendor_id used to write and read vendor id (hex)
27 device_id used to write and read device id (hex)
28 bar0_size used to write and read bar0_size
29 bar0_address used to write and read bar0 mapped area in hex.
30 bar0_rw_offset used to write and read offset of bar0 where bar0_data
32 bar0_data used to write and read data at bar0_rw_offset.
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| D | sysfs-bus-coresight-devices-cti | 67 Description: (RW) Read or write the CTIINEN register selected by inout_sel.
73 Description: (RW) Read or write the CTIOUTEN register selected by inout_sel.
79 Description: (RW) Read or write CTIGATE register.
85 Description: (RW) Read or write ASICCTL register.
91 Description: (Write) Write the INTACK register.
104 Description: (Write) Write APPCLEAR register to deactivate channel.
110 Description: (Write) Write APPPULSE to pulse a channel active for one clock
141 Description: (Write) Attach a CTI input trigger to a CTM channel.
147 Description: (Write) Detach a CTI input trigger from a CTM channel.
153 Description: (Write) Attach a CTI output trigger to a CTM channel.
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| D | sysfs-bus-iio-frequency-admv1013 | 5 Read/write unscaled value for the Local Oscillatior path quadrature I phase shift.
11 Read/write unscaled value for the Local Oscillatior path quadrature Q phase shift.
17 Read/write value for the Local Oscillatior Feedthrough Offset Calibration I Positive
24 Read/write value for the Local Oscillatior Feedthrough Offset Calibration Q Positive side.
30 Read/write raw value for the Local Oscillatior Feedthrough Offset Calibration I Negative
37 Read/write raw value for the Local Oscillatior Feedthrough Offset Calibration Q Negative
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| D | sysfs-platform-dfl-port | 30 Description: Read-write. Read this file for AP1 (AFU Power State 1) event.
31 It's used to indicate transient AP1 state. Write 1 to this
38 Description: Read-write. Read this file for AP2 (AFU Power State 2) event.
39 It's used to indicate transient AP2 state. Write 1 to this
46 Description: Read-write. Read or set AFU latency tolerance reporting value.
54 Description: Write-only. User writes command to this interface to set
68 Description: Write-only. User writes command to this interface to set
82 Description: Read-Write. Read this file to get errors detected on port and
83 Accelerated Function Unit (AFU). Write error code to this file
84 to clear errors. Write fails with -EINVAL if input parsing
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| /Documentation/userspace-api/media/v4l/ |
| D | func-write.rst | 4 .. _func-write:
7 V4L2 write()
13 v4l2-write - Write to a V4L2 device
22 .. c:function:: ssize_t write( int fd, void *buf, size_t count )
39 :c:func:`write()` writes up to ``count`` bytes to the device
42 enables them. When ``count`` is zero, :c:func:`write()` returns 0
55 variable is set appropriately. In this case the next write will start at
61 available to write the data immediately.
67 The driver does not support multiple write streams and the device is
80 The :c:func:`write()` function is not supported by this driver,
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| /Documentation/wmi/devices/ |
| D | msi-wmi-platform.rst | 26 [WmiDataId(1), read, write, Description("16 bytes of data")] uint8 Bytes[16];
33 [WmiDataId(1), read, write, Description("32 bytes of data")] uint8 Bytes[32];
43 [WmiMethodId(1), Implemented, read, write, Description("Return the contents of a package")]
46 [WmiMethodId(2), Implemented, read, write, Description("Set the contents of a package")]
49 [WmiMethodId(3), Implemented, read, write, Description("Return the contents of a package")]
52 [WmiMethodId(4), Implemented, read, write, Description("Set the contents of a package")]
55 [WmiMethodId(5), Implemented, read, write, Description("Return the contents of a package")]
58 [WmiMethodId(6), Implemented, read, write, Description("Set the contents of a package")]
61 [WmiMethodId(7), Implemented, read, write, Description("Return the contents of a package")]
64 [WmiMethodId(8), Implemented, read, write, Description("Set the contents of a package")]
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| /Documentation/devicetree/bindings/memory-controllers/ |
| D | st,stm32-fmc2-ebi-props.yaml | 25 8: Synchronous read synchronous write PSRAM.
26 9: Synchronous read asynchronous write PSRAM.
27 10: Synchronous read synchronous write NOR.
28 11: Synchronous read asynchronous write NOR.
90 phase in nanoseconds used for asynchronous read/write transactions.
94 phase in nanoseconds used for asynchronous multiplexed read/write
99 in nanoseconds used for asynchronous read/write transactions.
103 end of current read/write transaction and the next transaction.
107 in nanoseconds used for asynchronous read/write transactions.
117 st,fmc2-ebi-cs-write-address-setup-ns:
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| D | ti-aemif.txt | 99 between a read followed by read or a write
100 followed by a write to same chip select.
119 - ti,cs-write-setup-ns: write setup width, ns
121 and the activation of write strobe.
124 - ti,cs-write-strobe-ns: write strobe width, ns
126 the write strobe.
129 - ti,cs-write-hold-ns: write hold width, ns
130 Time between the deactivation of the write
169 ti,cs-write-hold-ns = <7>;
170 ti,cs-write-strobe-ns = <42>;
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| /Documentation/ABI/stable/ |
| D | sysfs-bus-nvmem | 6 This read/write attribute allows users to set read-write
7 devices as read-only and back to read-write from userspace.
8 This can be used to unlock and relock write-protection of
11 Read returns '0' or '1' for read-write or read-only modes
13 Write parses one of 'YyTt1NnFf0', or [oO][NnFf] for "on"
23 This file allows user to read/write the raw NVMEM contents.
24 Permissions for write to this file depends on the nvmem
|
| /Documentation/scsi/ |
| D | sd-parameters.rst | 9 Enable/disable drive write & read cache.
12 cache_type string WCE RCD Write cache Read cache
14 write through 0 0 off on
16 write back 1 0 on on
17 write back, no read (daft) 1 1 on off
20 To set cache type to "write back" and save this setting to the drive::
22 # echo "write back" > cache_type
27 # echo "temporary write back" > cache_type
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| /Documentation/filesystems/ |
| D | zonefs.rst | 12 device support (e.g. f2fs), zonefs does not hide the sequential write
14 write zones of the device must be written sequentially starting from the end
38 conventional zones. Any read or write access can be executed, similarly to a
41 sequentially. Each sequential zone has a write pointer maintained by the
42 device that keeps track of the mandatory start LBA position of the next write
43 to the device. As a result of this write constraint, LBAs in a sequential zone
53 to, for instance, reduce internal write amplification due to garbage collection.
73 information. File sizes come from the device zone type and write pointer
80 state to make it read-only, preventing any data write.
94 For sequential write zones, the sub-directory "seq" is used.
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| /Documentation/locking/ |
| D | seqlock.rst | 24 the end of the write side critical section the sequence count becomes
27 A sequence counter write side critical section must never be preempted
43 multiple writers. Write side critical sections must thus be serialized
46 If the write serialization primitive is not implicitly disabling
48 write side section. If the read section can be invoked from hardirq or
50 disabled before entering the write section.
70 Write path::
76 /* ... [[write-side critical section]] ... */
95 As discussed at :ref:`seqcount_t`, sequence count write side critical
98 initialization time, which enables lockdep to validate that the write
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| /Documentation/userspace-api/media/rc/ |
| D | lirc-write.rst | 4 .. _lirc-write:
7 LIRC write()
13 lirc-write - Write to a LIRC device
22 .. c:function:: ssize_t write( int fd, void *buf, size_t count )
39 :c:func:`write()` writes up to ``count`` bytes to the device
51 samples. The write function blocks until the data has been transmitted
62 ``EINVAL`` is returned. The write function blocks until the scancode
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| /Documentation/bpf/ |
| D | prog_cgroup_sysctl.rst | 11 process inside that cgroup tries to read from or write to sysctl knob in proc.
26 __u32 write;
30 * ``write`` indicates whether sysctl value is being read (``0``) or written
34 or written. This field is read-write. Writing to the field sets the starting
35 position in sysctl proc file ``read(2)`` will be reading from or ``write(2)``
37 whole sysctl value by ``bpf_sysctl_set_new_value()`` on ``write(2)`` even
56 ``write(2)`` and ``errno`` will be set to ``EPERM``.
69 ``read(2)`` from and ``write(2)`` to sysctl;
72 written to sysctl before actual write happens. This helper can be used only
73 on ``ctx->write == 1``;
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| /Documentation/devicetree/bindings/w1/ |
| D | w1-uart.yaml | 19 write bit or reset pulse.
22 a 1-Wire read or write operation 115200. In case the actual baud-rate
37 write-0-bps:
40 The baud rate for the 1-Wire write-0 cycle.
42 write-1-bps:
45 The baud rate for the 1-Wire write-1 and read cycle.
|
| /Documentation/arch/x86/ |
| D | mtrr.rst | 37 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
38 allows bus write transfers to be combined into a larger transfer
40 of image write operations 2.5 times or more.
50 The Centaur C6 (WinChip) has 8 MCRs, allowing write-combining. These
62 which allows you to read and write. The other is an ioctl()
73 reg00: base=0x00000000 ( 0MB), size= 128MB: write-back, count=1
74 reg01: base=0x08000000 ( 128MB), size= 64MB: write-back, count=1
78 # echo "base=0xf8000000 size=0x400000 type=write-combining" >! /proc/mtrr
82 # echo "base=0xf8000000 size=0x400000 type=write-combining" >| /proc/mtrr
87 reg00: base=0x00000000 ( 0MB), size= 128MB: write-back, count=1
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| /Documentation/networking/device_drivers/atm/ |
| D | cxacru-cf.py | 15 # this program; if not, write to the Free Software Foundation, Inc., 59
39 sys.stdout.write("\n")
40 sys.stderr.write("Error: read {0} not 4 bytes\n".format(len(buf)))
44 sys.stdout.write(" ")
45 sys.stdout.write("{0:x}={1}".format(i, struct.unpack("<I", buf)[0]))
48 sys.stdout.write("\n")
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| /Documentation/hwmon/ |
| D | oxp-sensors.rst | 76 Read Write. Enable manual fan control. Write "1" to set to manual, write "0"
80 Read Write. Read this attribute to see current duty cycle in the range [0-255].
81 When pwm1_enable is set to "1" (manual) write any value in the range [0-255]
85 Read Write. Read this attribute to check the status of the turbo/silent
86 button behaviour function. Write "1" to activate the switch and "0" to
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| /Documentation/admin-guide/device-mapper/ |
| D | log-writes.rst | 6 of the write operations to. This is intended for file system developers wishing
8 There is a log_write_entry written for every WRITE request and the target is
10 that is in the WRITE requests is copied into the log to make the replay happen
16 We log things in order of completion once we are sure the write is no longer in
17 cache. This means that normal WRITE requests are not actually logged until the
22 This works by attaching all WRITE requests to a list once the write completes.
27 following example (W means write, C means complete):
42 Any REQ_OP_DISCARD requests are treated like WRITE requests. Otherwise we would
43 have all the DISCARD requests, and then the WRITE requests and then the FLUSH
46 WRITE block 1, DISCARD block 1, FLUSH
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| /Documentation/filesystems/spufs/ |
| D | spufs.rst | 21 message queues. Users that have write permissions on the file system
44 tem calls like read(2) or write(2), but often support only a subset of
50 all files that support the write(2) operation also support writev(2).
68 read(2), pread(2), write(2), pwrite(2), lseek(2)
70 write(2) and pwrite(2) are not supported beyond the end of the
118 The CPU to SPU communation mailbox. It is write-only and can be written
119 in units of 32 bits. If the mailbox is full, write() will block and
121 operations on an open wbox file are: write(2) If a count smaller than
122 four is requested, write returns -1 and sets errno to EINVAL. If there
157 can be used in read/write mode for debugging, but normal operation of
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