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authorGravatar Rodrigo Vivi <rodrigo.vivi@intel.com> 2019-07-29 08:51:48 -0700
committerGravatar Rodrigo Vivi <rodrigo.vivi@intel.com> 2019-07-29 08:51:48 -0700
commited32f8d42cee118b075e4372a55c7739a11094b2 (patch)
tree5a806c5168d4177e0536b98b6bda30ec4bdbac43 /Documentation/admin-guide/device-mapper/delay.rst
parentdrm/i915: Flush the i915_vm_release before ggtt shutdown (diff)
parentLinus 5.3-rc1 (diff)
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Merge drm/drm-next into drm-intel-next-queued
Catching up with 5.3-rc* Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
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+========
+dm-delay
+========
+
+Device-Mapper's "delay" target delays reads and/or writes
+and maps them to different devices.
+
+Parameters::
+
+ <device> <offset> <delay> [<write_device> <write_offset> <write_delay>
+ [<flush_device> <flush_offset> <flush_delay>]]
+
+With separate write parameters, the first set is only used for reads.
+Offsets are specified in sectors.
+Delays are specified in milliseconds.
+
+Example scripts
+===============
+
+::
+
+ #!/bin/sh
+ # Create device delaying rw operation for 500ms
+ echo "0 `blockdev --getsz $1` delay $1 0 500" | dmsetup create delayed
+
+::
+
+ #!/bin/sh
+ # Create device delaying only write operation for 500ms and
+ # splitting reads and writes to different devices $1 $2
+ echo "0 `blockdev --getsz $1` delay $1 0 0 $2 0 500" | dmsetup create delayed