Documentation for ndctl and daxctl


NAME

daxctl-reconfigure-device - Reconfigure a dax device into a different mode

SYNOPSIS

daxctl reconfigure-device <dax0.0> [<dax1.0>…​<daxY.Z>] [<options>]

EXAMPLES

# daxctl reconfigure-device --mode=system-ram --no-online dax0.0
[
  {
    "chardev":"dax0.0",
    "size":16777216000,
    "target_node":2,
    "mode":"system-ram"
  }
]
# daxctl reconfigure-device --human --mode=devdax --force dax0.0
{
  "chardev":"dax0.0",
  "size":"15.63 GiB (16.78 GB)",
  "target_node":2,
  "mode":"devdax"
}
# daxctl reconfigure-device --mode=system-ram --region=0 all
[
  {
    "chardev":"dax0.0",
    "size":16777216000,
    "target_node":2,
    "mode":"system-ram"
  },
  {
    "chardev":"dax0.1",
    "size":16777216000,
    "target_node":3,
    "mode":"system-ram"
  }
]
# daxctl reconfigure-device --mode=system-ram dax0.0
[
  {
    "chardev":"dax0.0",
    "size":16777216000,
    "target_node":2,
    "mode":"system-ram"
  }
]

# numactl --cpunodebind=0-1 --membind=2 -- some-service --opt1 --opt2

DESCRIPTION

Reconfigure the operational mode of a dax device. This can be used to convert a regular devdax mode device to the system-ram mode which arranges for the dax range to be hot-plugged into the system as regular memory.

Note

This is a destructive operation. Any data on the dax device will be lost.

Note

Device reconfiguration depends on the dax-bus device model. See daxctl-migrate-device-model for more information. If dax-class is in use (via the dax_pmem_compat driver), the reconfiguration will fail with an error such as the following:

# daxctl reconfigure-device --mode=system-ram --region=0 all
libdaxctl: daxctl_dev_disable: dax3.0: error: device model is dax-class
dax3.0: disable failed: Operation not supported
error reconfiguring devices: Operation not supported
reconfigured 0 devices

OPTIONS

-r; --region=
Restrict the operation to devices belonging to the specified region(s). A device-dax region is a contiguous range of memory that hosts one or more /dev/daxX.Y devices, where X is the region id and Y is the device instance id.

-m; --mode=
Specify the mode to which the dax device(s) should be reconfigured.

-N; --no-online
By default, memory sections provided by system-ram devices will be brought online automatically and immediately with the online_movable policy. Use this option to disable the automatic onlining behavior.

NOTE: While this option prevents daxctl from automatically onlining
the memory sections, there may be other agents, notably system udev
rules, that online new memory sections as they appear. Coordinating
with such rules is out of scope of this utility, and the system
administrator is expected to remove them if they are undesirable.
If such an agent races to online memory sections, daxctl is prepared
to lose the race, and not fail the onlining operation as it only
cares that the memory section was onlined, not that it was the one
to do so.

-f; --force
When converting from “system-ram” mode to “devdax”, it is expected that all the memory sections are first made offline. By default, daxctl won’t touch online memory. However with this option, attempt to offline the memory on the NUMA node associated with the dax device before converting it back to “devdax” mode.

-u; --human
By default the command will output machine-friendly raw-integer data. Instead, with this flag, numbers representing storage size will be formatted as human readable strings with units, other fields are converted to hexadecimal strings.

-v; --verbose
Emit more debug messages

COPYRIGHT

Copyright (c) 2016 - 2019, Intel Corporation. License GPLv2: GNU GPL version 2 http://gnu.org/licenses/gpl.html. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.

SEE ALSO

daxctl-list,daxctl-migrate-device-model